@article{PrieskeMuehlbauerBordeetal.2016, author = {Prieske, Olaf and M{\"u}hlbauer, Thomas and Borde, Ron and Gube, M. and Bruhn, S. and Behm, David George and Granacher, Urs}, title = {Neuromuscular and athletic performance following core strength training in elite youth soccer: Role of instability}, series = {Learning and individual differences}, volume = {26}, journal = {Learning and individual differences}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0905-7188}, doi = {10.1111/sms.12403}, pages = {48 -- 56}, year = {2016}, abstract = {Cross-sectional studies revealed that inclusion of unstable elements in core-strengthening exercises produced increases in trunk muscle activity and thus potential extra stimuli to induce more pronounced performance enhancements in youth athletes. Thus, the purpose of the study was to investigate changes in neuromuscular and athletic performance following core strength training performed on unstable (CSTU) compared with stable surfaces (CSTS) in youth soccer players. Thirty-nine male elite soccer players (age: 17 +/- 1 years) were assigned to two groups performing a progressive core strength-training program for 9 weeks (2-3 times/week) in addition to regular in-season soccer training. CSTS group conducted core exercises on stable (i.e., floor, bench) and CSTU group on unstable (e.g., Thera-Band (R) Stability Trainer, Togu (c) Swiss ball) surfaces. Measurements included tests for assessing trunk muscle strength/activation, countermovement jump height, sprint time, agility time, and kicking performance. Statistical analysis revealed significant main effects of test (pre vs post) for trunk extensor strength (5\%, P<0.05, d=0.86), 10-20-m sprint time (3\%, P<0.05, d=2.56), and kicking performance (1\%, P<0.01, d=1.28). No significant Groupxtest interactions were observed for any variable. In conclusion, trunk muscle strength, sprint, and kicking performance improved following CSTU and CSTS when conducted in combination with regular soccer training.}, language = {en} } @article{GranacherGruberGollhofer2009, author = {Granacher, Urs and Gruber, Markus and Gollhofer, Albert}, title = {Resistance training and neuromuscular performance in seniors}, issn = {0172-4622}, doi = {10.1055/s-0029-1224178}, year = {2009}, abstract = {Age-related processes in the neuromuscular and the somatosensory system are responsible for decreases in maximal and explosive force production capacity and deficits in postural control. Thus, the objectives of this study were to investigate the effects of resistance training on strength performance and on postural control in seniors. Forty healthy seniors (67 +/- 1 yrs) participated in this study. Subjects were randomly assigned to a resistance training (n = 20) and a control group (n = 20). Resistance training for the lower extremities lasted for 13 weeks at 80\% of the one repetition maximum. Pre and post tests included the measurement of maximal isometric leg extension force with special emphasis on the early part of the force-time-curve and the assessment of static (functional reach test) and dynamic (tandem walk test, platform perturbation) postural control. Resistance training resulted I in an enhanced strength performance with increases I in explosive force exceeding those in maximal strength. Improved performances in the functional reach and in the tandem walk test were observed. Resistance training did not have an effect: on the compensation of platform perturbations. Increases in strength performance can primarily be explained by an improved neural drive of the agonist muscles. The inconsistent effect of resistance training on postural control may be explained by heterogeneity of testing methodology or by the incapability of isolated resisiance training to improve postural control.}, language = {en} } @article{WallentaGranacherLesinskietal.2016, author = {Wallenta, Christopher and Granacher, Urs and Lesinski, Melanie and Schuenemann, C. and M{\"u}hlbauer, Thomas}, title = {Effects of Complex Versus Block Strength Training on the Athletic Performance of Elite Youth Soccer Players}, series = {Sportverletzung, Sportschaden : Grundlagen, Pr{\~A}\ivention, Rehabilitation}, volume = {30}, journal = {Sportverletzung, Sportschaden : Grundlagen, Pr{\~A}\ivention, Rehabilitation}, publisher = {Thieme}, address = {Stuttgart}, issn = {0932-0555}, doi = {10.1055/s-0041-106949}, pages = {31 -- 37}, year = {2016}, abstract = {Hintergrund: Kraft und Schnelligkeit stellen bedeutsame leistungsdeterminierende Faktoren im Fußball dar. Durch Komplextraining (Kombination aus Kraft- und plyometrischen {\"U}bungen in einer Trainingseinheit) lassen sich Kraft- und Schnelligkeitswerte von Athleten steigern. Unklar ist jedoch, ob ein Komplextraining (KT) gegen{\"u}ber einem herk{\"o}mmlichen blockweisen Krafttraining (BT) zu gr{\"o}ßeren sportmotorischen Leistungssteigerungen f{\"u}hrt. Das Ziel der Studie war es, die Effekte von KT versus BT auf Variablen der Kraft, Schnelligkeit und Gewandtheit von Nachwuchsleistungsfußballern zu untersuchen. Methode: Zus{\"a}tzlich zum regul{\"a}ren Fußballtraining (ca. 6 × pro Woche, je 60 - 90 min.) f{\"u}hrten 18 m{\"a}nnliche Nachwuchsleistungsfußballer {\"u}ber sechs Wochen (2 × pro Woche, je 30 min.) entweder ein progressives KT (n = 10, Alter: 18,5 ± 2,2 Jahre) oder BT (n = 8, Alter: 18,1 ± 1,6 Jahre) durch. Vor und nach dem Training wurden Tests zur Erfassung der Kraft (Einer-Wiederholungs-Maximum [EWM] Kniebeuge), der Sprungkraft (Hockstrecksprung [HSS]), der Schnelligkeit (30-m-Sprint) und der Gewandtheit (T-Test) durchgef{\"u}hrt. Es wurden parameterfreie Verfahren zur Bestimmung von Unterschieden innerhalb (Wilcoxon-Test) und zwischen (Mann-Whitney-U-Test) den beiden Gruppen gerechnet. Ergebnisse: Sowohl KT als auch BT sind sichere (keine trainings- aber sechs spielbedingte Verletzungen) und geeignete (Trainingsteilnahme in KT und BT: \&\#8805; 80 \%) Trainingsmaßnahmen in Erg{\"a}nzung zum regul{\"a}ren Fußballtraining. Die statistische Analyse ergab signifikante Verbesserungen vom Pr{\"a}- zum Posttest f{\"u}r die KT-Gruppe im EWM (p = 0,043) und im HSS (p = 0,046) sowie f{\"u}r die BT-Gruppe in der Sprintzeit {\"u}ber 5 m (p = 0,039) und 10 m (p = 0,026). Zudem zeigten sich f{\"u}r beide Gruppen signifikante Verbesserungen im T-Test (KT: p = 0,046; BT: p = 0,027). Der Gruppenvergleich (KT vs. BT) {\"u}ber die Zeit (Post- minus Pr{\"a}test) offenbarte keine bedeutsamen Unterschiede. Schlussfolgerung: Sowohl sechsw{\"o}chiges KT als auch BT f{\"u}hrten zu signifikanten Verbesserungen sportmotorischer Leistungen bei Nachwuchsleistungsfußballern. Allerdings konnten keine zus{\"a}tzlich leistungssteigernden Effekte von KT im Vergleich zu BT ermittelt werden. In zuk{\"u}nftigen Studien sollte gepr{\"u}ft werden, ob die beobachteten testspezifischen Ver{\"a}nderungen, d. h. Verbesserung der Kraft/Sprungkraft in der KT-Gruppe und Verbesserung der Schnelligkeit in der BT-Gruppe der gew{\"a}hlten {\"U}bungsanordnung geschuldet sind oder einen generellen Effekt darstellen. Background: Muscle strength and speed are important determinants of soccer performance. It has previously been shown that complex training (CT, combination of strength and plyometric exercises within a single training session) is effective to enhance strength and speed performance in athletes. However, it is unresolved whether CT is more effective than conventional strength training that is delivered in one single block (BT) to increase proxies of athletic performance. Thus, the aim of the present study was to investigate the effects of CT versus BT on measures of muscle strength/power, speed, and agility in elite youth soccer players. Methods: Eighteen male elite youth soccer players conducted six weeks (2 sessions/week, 30 min, each) of progressive CT (n = 10, age: 18,5 +/- 2.2 years) or BT (n=8, age: 18.1 +/- 1.6 years) in addition to their regular soccer training (approx. 6 sessions/week, 60-90 min, each). Before and after training, tests were conducted for the assessment of strength (one -repetition maximum [1RM] squat), power (countermovement jump [CMJ]), speed (30-m linear sprint), and agility (T test). Non-parametric analyses were used to calculate differences within (Wilcoxon test) and between (Mann-Whitney-U test) groups. Results: Both CT and BT proved to be safe (i.e. no training-related, but six match -related injuries reported) and feasible (i.e. attendance rate of 80\% in both groups) training regimens when implemented in addition to regular soccer training. The statistical analysis revealed significant improvements from pre-training to post-training tests for the CT group in 1 RM squat (p =0.043) and CMJ height (p =0,046). For the BT -group, significantly enhanced sprint times were observed over 5 m (p = 0.039) and 10 m (p = 0.026), Furthermore, both groups significantly improved their t test time (CT: p =0.046; BT: p =0.027). However, group comparisons (CT vs. BT) over time (post-training minus pre-training test) did not show any significant differences. Conclusion: Six weeks of CT and BT resulted in significant improvements in proxies of athletic performance. Yet CT did not produce any additional effects compared to BT. Future research is needed to examine whether the observed test-specific changes, i.e. improvements in strength/power for the CT-group and improvements in speed for the BT-group, are due to the applied configuration of strength, plyometric, and sprint exercises or if they rather indicate a general training response.}, language = {de} } @article{HaileFuehnerGranacheretal.2021, author = {Haile, Sarah R. and F{\"u}hner, Thea Heidi and Granacher, Urs and Stocker, Julien and Radtke, Thomas and Kriemler, Susi}, title = {Reference values and validation of the 1-minute sit-to-stand test in healthy 5-16-year-old youth}, series = {BMJ open}, volume = {11}, journal = {BMJ open}, number = {5}, publisher = {BMJ Publishing Group}, address = {London}, issn = {2044-6055}, doi = {10.1136/bmjopen-2021-049143}, pages = {7}, year = {2021}, abstract = {Objectives: It is essential to have simple, reliable and valid tests to measure children's functional capacity in schools or medical practice. The 1-minute sit-to-stand (STS) test is a quick fitness test requiring little equipment or space that is increasingly used in both healthy populations and those with chronic disease. We aimed to provide age-specific and sex-specific reference values of STS test in healthy children and adolescents and to evaluate its short-term reliability and construct validity. Design setting and participants: Cross-sectional convenience sample from six public schools and one science fair in central Europe. Overall, 587 healthy participants aged 5-16 years were recruited and divided into age groups of 3 years each. Outcomes: 1-minute STS. To evaluate short-term reliability, some children performed the STS test twice. To evaluate construct validity, some children also performed a standing long jump (SLJ) and a maximal incremental exercise test. Results: Data from 547 youth aged 5-16 years were finally included in the analyses. The median number of repetitions in 1 min in males (females) ranged from 55 [95\% CI: 38 to 72] (53 [95\% CI: 35 to 76]) in 14-16-year olds to 59 [95\% CI: 41 to 77] (60 [95\% CI: 38 to 77]) in 8-10-year olds. Children who repeated STS showed a learning effect of on average 4.8 repetitions more than the first test (95\% limits of agreement: -6.7 to 16.4). Moderate correlations were observed between the STS and the SLJ (r=0.48) tests and the maximal exercise test (r=0.43). Conclusions: The reported STS reference values can be used to interpret STS test performance in children and adolescents. The STS appears to have good test- retest reliability, but a learning effect of about 10\%. The association of STS with other measures of physical fitness should be further explored in a larger study and technical standards for its conduct are needed.}, language = {en} } @misc{PrieskeMuehlbauerGranacher2016, author = {Prieske, Olaf and M{\"u}hlbauer, Thomas and Granacher, Urs}, title = {The Role of Trunk Muscle Strength for Physical Fitness and Athletic Performance in Trained Individuals: A Systematic Review and Meta-Analysis}, series = {Sports medicine}, volume = {46}, journal = {Sports medicine}, publisher = {Springer}, address = {Northcote}, issn = {0112-1642}, doi = {10.1007/s40279-015-0426-4}, pages = {401 -- 419}, year = {2016}, abstract = {Background The importance of trunk muscle strength (TMS) for physical fitness and athletic performance has been demonstrated by studies reporting significant correlations between those capacities. However, evidence-based knowledge regarding the magnitude of correlations between TMS and proxies of physical fitness and athletic performance as well as potential effects of core strength training (CST) on TMS, physical fitness and athletic performance variables is currently lacking for trained individuals. Objective The aims of this systematic review and meta-analysis were to quantify associations between variables of TMS, physical fitness and athletic performance and effects of CST on these measures in healthy trained individuals. Data Sources PubMed, Web of Science, and SPORTDiscus were systematically screened from January 1984 to March 2015. Study Eligibility Criteria Studies were included that investigated healthy trained individuals aged 16-44 years and tested at least one measure of TMS, muscle strength, muscle power, balance, and/or athletic performance. Results Small-sized relationships of TMS with physical performance measures (-0.05 <= r <= 0.18) were found in 15 correlation studies. Sixteen intervention studies revealed large effects of CST on measures of TMS (SMD = 1.07) but small-to-medium-sized effects on proxies of physical performance (0 <= SMD <= 0.71) compared with no training or regular training only. The methodological quality of CST studies was low (median PEDro score = 4). Conclusions Our findings indicate that TMS plays only a minor role for physical fitness and athletic performance in trained individuals. In fact, CST appears to be an effective means to increase TMS and was associated with only limited gains in physical fitness and athletic performance measures when compared with no or only regular training.}, language = {en} } @misc{BehmMuehlbauerKibeleetal.2016, author = {Behm, David George and M{\"u}hlbauer, Thomas and Kibele, Armin and Granacher, Urs}, title = {Effects of Strength Training Using Unstable Surfaces on Strength, Power and Balance Performance Across the Lifespan: A Systematic Review and Meta-analysis (vol 45, pg 1645, 2015)}, series = {Sports medicine}, volume = {46}, journal = {Sports medicine}, publisher = {Springer}, address = {Northcote}, issn = {0112-1642}, doi = {10.1007/s40279-016-0497-x}, pages = {451 -- 451}, year = {2016}, language = {en} } @article{JafarnezhadgeroGhorbanlooFatollahietal.2021, author = {Jafarnezhadgero, AmirAli and Ghorbanloo, Farshad and Fatollahi, Amir and Dionisio, Valdeci Carlos and Granacher, Urs}, title = {Effects of an elastic resistance band exercise program on kinetics and muscle activities during walking in young adults with genu valgus}, series = {Clinical biomechanics : a journal affiliated to the International Society of Biomechanics and the American Society of Biomechanics}, volume = {81}, journal = {Clinical biomechanics : a journal affiliated to the International Society of Biomechanics and the American Society of Biomechanics}, publisher = {Elsevier Science}, address = {Amsterdam [u.a.]}, issn = {0268-0033}, doi = {10.1016/j.clinbiomech.2020.105215}, pages = {10}, year = {2021}, abstract = {Background: This double-blinded randomized-controlled-trial aimed to identify the effects of an elastic band resistance training on walking kinetics and muscle activities in young adults with genu valgus. Methods: Forty-two male young adults aged 22.5(2.7) years with genu valgus were randomly allocated to two experimental groups. The intervention group (n = 21) conducted a 14-weeks elastic band resistance training. The control group was passive during the intervention period and received the same treatment after the post-tests. Pre and post training, ground reaction forces and lower limb muscle activities were recorded during walking. Findings: Results revealed significant group-by-time interactions for peak medial ground reaction force and timeto-peak for posterior ground reaction force in favor of the intervention group (p < 0.012; d = 0.83-3.76). Resistance training with elastic bands resulted in significantly larger peak medial ground reaction force (p < 0.001; d = 1.45) and longer time-to-peak for posterior ground reaction force (p < 0.001; d = 1.85). Finding showed significant group-by-time interactions for peak positive free moment amplitudes in favor of the intervention group (p < 0.001; d = 1.18-2.02). Resistance training resulted in a lower peak positive free moment amplitude (p = 0.001; d = 1.46). With regards to muscle activities, the analysis revealed significant group-by time interactions for rectus femoris and gluteus medius activities during the push-off phase in favor of the intervention group (p < 0.038; d = 0.68-0.89). Resistance training induced higher rectus femoris (p = 0.038; d = 0.84) and gluteus medius (p = 0.007; d = 0.54) activities. Interpretation: This study proved the effectiveness of resistance training using elastic bands on kinetics and muscle activities during walking in male adults with genu valgus disorder. Given that this training regime is low cost, effective, and easy-to-administer, we suggest that it should be implemented as a rehabilitative or preventive means for young adults with genu valgus.}, language = {en} } @article{WickKriemlerGranacher2021, author = {Wick, Kristin and Kriemler, Susi and Granacher, Urs}, title = {Effects of a strength-dominated exercise program on physical fitness and cognitive performance in preschool children}, series = {Journal of strength and conditioning research : the research journal of the NSCA}, volume = {35}, journal = {Journal of strength and conditioning research : the research journal of the NSCA}, number = {4}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {1064-8011}, doi = {10.1519/JSC.0000000000003942}, pages = {983 -- 990}, year = {2021}, abstract = {Wick, K, Kriemler, S, and Granacher, U. Effects of a strength-dominated exercise program on physical fitness and cognitive performance in preschool children. J Strength Cond Res 35(4): 983-990, 2021-Childhood is characterized by high neuroplasticity that affords qualitative rather than quantitative components of physical activity to maximize the potential to sufficiently develop motor skills and foster long-term engagement in regular physical activity. This study examined the effects of an integrative strength-dominated exercise program on measures of physical fitness and cognitive performance in preschool children. Children aged 4-6 years from 3 kindergartens were randomized into an intervention (INT) group (n = 32) or a control group (n = 22). The 10-week intervention period was conducted 3 times per week (each session lasted 30 minutes) and included exercises for the promotion of muscle strength and power, coordination, and balance. Pre and post training, tests were conducted for the assessment of muscle strength (i.e., handgrip strength), muscle power (i.e., standing long jump), balance (i.e., timed single-leg stand), coordination (hopping on right/left leg), and attentional span (i.e., "Konzentrations-Handlungsverfahren fur Vorschulkinder" [concentration-action procedure for preschoolers]). Results from 2 x 2 repeated-measures analysis of covariance revealed a significant (p <= 0.05) and near significant (p = 0.051) group x time interaction for the standing long jump test and the Konzentrations-Handlungsverfahren. Post hoc tests showed significant pre-post changes for the INT (p < 0.001; d = 1.53) but not the CON (p = 0.72; d = 0.83). Our results indicate that a 10-week strength-dominated exercise program increased jump performance with a concomitant trend toward improvements in attentional capacity of preschool children. Thus, we recommend implementing this type of exercise program for preschoolers.}, language = {en} } @article{ChaouachiGranacherMakhloufetal.2017, author = {Chaouachi, Mehdi and Granacher, Urs and Makhlouf, Issam and Hammami, Raouf and Behm, David G. and Chaouachi, Anis}, title = {Within Session Sequence of Balance and Plyometric Exercises Does Not Affect Training Adaptations with Youth Soccer Athletes}, series = {Journal of sports science \& medicine}, volume = {16}, journal = {Journal of sports science \& medicine}, publisher = {Department of Sports Medicine, Medical Faculty of Uludag University}, address = {Bursa}, issn = {1303-2968}, pages = {125 -- 136}, year = {2017}, abstract = {The integration of balance and plyometric training has been shown to provide significant improvements in sprint, jump, agility, and other performance measures in young athletes. It is not known if a specific within session balance and plyometric exercise sequence provides more effective training adaptations. The objective of the present study was to investigate the effects of using a sequence of alternating pairs of exercises versus a block (series) of all balance exercises followed by a block of plyometric exercises on components of physical fitness such as muscle strength, power, speed, agility, and balance. Twenty-six male adolescent soccer players ( 13.9 +/- 0.3 years) participated in an 8-week training program that either alternated individual balance (e. g., exercises on unstable surfaces) and plyometric (e. g., jumps, hops, rebounds) exercises or performed a block of balance exercises prior to a block of plyometric exercises within each training session. Pre- and post-training measures included proxies of strength, power, agility, sprint, and balance such as countermovement jumps, isometric back and knee extension strength, standing long jump, 10 and 30-m sprints, agility, standing stork, and Y-balance tests. Both groups exhibited significant, generally large magnitude (effect sizes) training improvements for all measures with mean performance increases of approximately > 30\%. There were no significant differences between the training groups over time. The results demonstrate the effectiveness of combining balance and plyometric exercises within a training session on components of physical fitness with young adolescents. The improved performance outcomes were not significantly influenced by the within session exercise sequence.}, language = {en} } @article{BeurskensSteinbergAntoniewiczetal.2016, author = {Beurskens, Rainer and Steinberg, Fabian and Antoniewicz, Franziska and Wolff, Wanja and Granacher, Urs}, title = {Neural Correlates of Dual-Task Walking: Effects of Cognitive versus Motor Interference in Young Adults}, series = {Neural plasticity}, journal = {Neural plasticity}, publisher = {Hindawi}, address = {London}, issn = {2090-5904}, doi = {10.1155/2016/8032180}, pages = {9}, year = {2016}, abstract = {Walking while concurrently performing cognitive and/or motor interference tasks is the norm rather than the exception during everyday life and there is evidence from behavioral studies that it negatively affects human locomotion. However, there is hardly any information available regarding the underlying neural correlates of single-and dual-task walking. We had 12 young adults (23.8 +/- 2.8 years) walk while concurrently performing a cognitive interference (CI) or a motor interference (MI) task. Simultaneously, neural activation in frontal, central, and parietal brain areas was registered using a mobile EEG system. Results showed that the MI task but not the CI task affected walking performance in terms of significantly decreased gait velocity and stride length and significantly increased stride time and tempo-spatial variability. Average activity in alpha and beta frequencies was significantly modulated during both CI and MI walking conditions in frontal and central brain regions, indicating an increased cognitive load during dual-task walking. Our results suggest that impaired motor performance during dual-task walking is mirrored in neural activation patterns of the brain. This finding is in line with established cognitive theories arguing that dual-task situations overstrain cognitive capabilities resulting in motor performance decrements.}, language = {en} } @book{MuehlbauerRothKibeleetal.2013, author = {M{\"u}hlbauer, Thomas and Roth, Ralf and Kibele, Armin and Behm, David George and Granacher, Urs}, title = {Krafttraining mit Kindern und Jugendlichen}, series = {Praxisideen}, journal = {Praxisideen}, number = {58}, editor = {Kr{\"o}ger, Christian and Roth, Klaus and Haag, Herbert}, publisher = {Hofmann}, address = {Schorndorf}, isbn = {978-3-7780-2581-9}, pages = {192}, year = {2013}, abstract = {Dieser Band besch{\"a}ftigt sich mit den theoretischen Grundlagen und der praktischen Umsetzung von Krafttraining mit Kindern und Jugendlichen. Ausgehend von der Kennzeichnung der k{\"o}rperlichen Situation und der Kraftentwicklung im Kindes- und Jugendalter werden die Effekte von Krafttraining bei Kindern und Jugendlichen aufgezeigt. Hierzu z{\"a}hlen neben Verbesserungen der Kraftausdauer, der Maximal- und Schnellkraft, die F{\"o}rderung elementarer und sportartspezifischer Fertigkeiten sowie die g{\"u}nstige Beeinflussung gesundheitsrelevanter Faktoren (u.a. Verletzungsh{\"a}ufigkeit, Knochenstatus, kardio-vaskul{\"a}re und psycho-soziale Kennwerte). Im Anschluss werden neuronale und muskul{\"a}re Mechanismen zur Erkl{\"a}rung der trainingsbedingten Anpassungen beschrieben. Das Kernst{\"u}ck des Buches bildet die Darstellung und Beschreibung vielf{\"a}ltiger {\"U}bungsbeispiele f{\"u}r ein Krafttraining an Maschinen, mit Freihanteln, Zusatzger{\"a}ten, dem eigenen K{\"o}rpergewicht und ein Sprungkrafttraining. Hierbei wurden insbesondere {\"U}bungen ausgew{\"a}hlt, die sich f{\"u}r den Einsatz im Schul- und Vereinssport eignen. Dieses Buch dient somit Lehrern, {\"U}bungsleitern und Trainern, ein zielgerichtetes Krafttraining mit Kindern und Jugendlichen wirkungsvoll und sicher durchzuf{\"u}hren.}, language = {de} } @article{PrieskeAboodardaSierraetal.2017, author = {Prieske, Olaf and Aboodarda, Saied J. and Sierra, Jose A. Benitez and Behm, David G. and Granacher, Urs}, title = {Slower but not faster unilateral fatiguing knee extensions alter contralateral limb performance without impairment of maximal torque output}, series = {European journal of applied physiology}, volume = {117}, journal = {European journal of applied physiology}, publisher = {Springer}, address = {New York}, issn = {1439-6319}, doi = {10.1007/s00421-016-3524-6}, pages = {323 -- 334}, year = {2017}, abstract = {The purpose of the present study was to examine the effects of unilateral fatigue of the knee extensors at different movement velocities on neuromuscular performance in the fatigued and non-fatigued leg. Unilateral fatigue of the knee extensors was induced in 11 healthy young men (23.7 +/- 3.8 years) at slower (60A degrees/s; FAT60) and faster movement velocities (240A degrees/s; FAT240) using an isokinetic dynamometer. A resting control (CON) condition was included. The fatigue protocols consisted of five sets of 15 maximal concentric knee extensions using the dominant leg. Before and after fatigue, peak isokinetic torque (PIT) and time to PIT (TTP) of the knee extensors as well as electromyographic (EMG) activity of vastus medialis, vastus lateralis, and biceps femoris muscles were assessed at 60 and 240A degrees/s movement velocities in the fatigued and non-fatigued leg. In the fatigued leg, significantly greater PIT decrements were observed following FAT60 and FAT240 (11-19\%) compared to CON (3-4\%, p = .002, d = 2.3). Further, EMG activity increased in vastus lateralis and biceps femoris muscle following FAT240 only (8-28\%, 0.018 <= p <=.024, d = 1.8). In the non-fatigued leg, shorter TTP values were found after the FAT60 protocol (11-15\%, p = .023, d = 2.4). No significant changes were found for EMG data in the non-fatigued leg. The present study revealed that both slower and faster velocity fatiguing contractions failed to show any evidence of cross-over fatigue on PIT. However, unilateral knee extensor fatigue protocols conducted at slower movement velocities (i.e., 60A degrees/s) appear to modulate torque production on the non-fatigued side (evident in shorter TTP values).}, language = {en} } @article{JafarnezhadgeroFatollahiGranacher2022, author = {Jafarnezhadgero, Amir Ali and Fatollahi, Amir and Granacher, Urs}, title = {Eight weeks of exercising on sand has positive effects on biomechanics of walking and muscle activities in individuals with pronated feet}, series = {Sports : open access journal}, volume = {10}, journal = {Sports : open access journal}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2075-4663}, doi = {10.3390/sports10050070}, pages = {16}, year = {2022}, abstract = {This study aimed to investigate the effects of eight weeks of barefoot running exercise on sand versus control on measures of walking kinetics and muscle activities in individuals with diagnosed pronated feet. Sixty physically active male adults with pronated feet were randomly allocated into an intervention or a waiting control group. The intervention group conducted an 8-weeks progressive barefoot running exercise program on sand (e.g., short sprints) with three weekly sessions. Pre and post intervention, participants walked at a constant speed of 1.3 m/s +/- 5\% on a 18 m walkway with a force plate embedded in the middle of the walkway. Results showed significant group-by-time interactions for peak impact vertical and lateral ground reaction forces. Training but not control resulted in significantly lower peak impact vertical and lateral ground reaction forces. Significant group-by-time interactions were observed for vastus lateralis activity during the loading phase. Training-induced increases were found for the vastus lateralis in the intervention but not in the control group. This study revealed that the applied exercise program is a suitable means to absorb ground reaction forces (e.g., lower impact vertical and lateral peaks) and increase activities of selected lower limb muscles (e.g., vastus lateralis) when walking on stable ground.}, language = {en} } @misc{GebelBuschStelzeletal.2022, author = {Gebel, Arnd and Busch, Aglaja and Stelzel, Christine and Hortob{\´a}gyi, Tibor and Granacher, Urs}, title = {Effects of Physical and Mental Fatigue on Postural Sway and Cortical Activity in Healthy Young Adults}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {1866-8364}, doi = {10.25932/publishup-56441}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-564419}, pages = {1 -- 14}, year = {2022}, abstract = {Physical fatigue (PF) negatively affects postural control, resulting in impaired balance performance in young and older adults. Similar effects on postural control can be observed for mental fatigue (MF) mainly in older adults. Controversial results exist for young adults. There is a void in the literature on the effects of fatigue on balance and cortical activity. Therefore, this study aimed to examine the acute effects of PF and MF on postural sway and cortical activity. Fifteen healthy young adults aged 28 ± 3 years participated in this study. MF and PF protocols comprising of an all-out repeated sit-to-stand task and a computer-based attention network test, respectively, were applied in random order. Pre and post fatigue, cortical activity and postural sway (i.e., center of pressure displacements [CoPd], velocity [CoPv], and CoP variability [CV CoPd, CV CoPv]) were tested during a challenging bipedal balance board task. Absolute spectral power was calculated for theta (4-7.5 Hz), alpha-2 (10.5-12.5 Hz), beta-1 (13-18 Hz), and beta-2 (18.5-25 Hz) in frontal, central, and parietal regions of interest (ROI) and baseline-normalized. Inference statistics revealed a significant time-by-fatigue interaction for CoPd (p = 0.009, d = 0.39, Δ 9.2\%) and CoPv (p = 0.009, d = 0.36, Δ 9.2\%), and a significant main effect of time for CoP variability (CV CoPd: p = 0.001, d = 0.84; CV CoPv: p = 0.05, d = 0.62). Post hoc analyses showed a significant increase in CoPd (p = 0.002, d = 1.03) and CoPv (p = 0.003, d = 1.03) following PF but not MF. For cortical activity, a significant time-by-fatigue interaction was found for relative alpha-2 power in parietal (p < 0.001, d = 0.06) areas. Post hoc tests indicated larger alpha-2 power increases after PF (p < 0.001, d = 1.69, Δ 3.9\%) compared to MF (p = 0.001, d = 1.03, Δ 2.5\%). In addition, changes in parietal alpha-2 power and measures of postural sway did not correlate significantly, irrespective of the applied fatigue protocol. No significant changes were found for the other frequency bands, irrespective of the fatigue protocol and ROI under investigation. Thus, the applied PF protocol resulted in increased postural sway (CoPd and CoPv) and CoP variability accompanied by enhanced alpha-2 power in the parietal ROI while MF led to increased CoP variability and alpha-2 power in our sample of young adults. Potential underlying cortical mechanisms responsible for the greater increase in parietal alpha-2 power after PF were discussed but could not be clearly identified as cause. Therefore, further future research is needed to decipher alternative interpretations.}, language = {en} } @article{BeijersbergenHortobagyiBeurskensetal.2016, author = {Beijersbergen, Chantal M. I. and Hortobagyi, Tibor and Beurskens, Rainer and Lenzen-Grossimlinghaus, Romana and Gabler, Martijn and Granacher, Urs}, title = {Effects of Power Training on Mobility and Gait Biomechanics in Old Adults with Moderate Mobility Disability: Protocol and Design of the Potsdam Gait Study (POGS)}, series = {Gerontology}, volume = {62}, journal = {Gerontology}, publisher = {Karger}, address = {Basel}, issn = {0304-324X}, doi = {10.1159/000444752}, pages = {597 -- 603}, year = {2016}, abstract = {Background: Walking speed decreases in old age. Even though old adults regularly participate in exercise interventions, we do not know how the intervention-induced changes in physical abilities produce faster walking. The Potsdam Gait Study (POGS) will examine the effects of 10 weeks of power training and detraining on leg muscle power and, for the first time, on complete gait biomechanics, including joint kinematics, kinetics, and muscle activation in old adults with moderate mobility disability. Methods/Design: POGS is a randomized controlled trial with two arms, each crossed over, without blinding. Arm 1 starts with a 10-week control period to assess the reliability of the tests and is then crossed over to complete 25-30 training sessions over 10 weeks. Arm 2 completes 25-30 exercise sessions over 10 weeks, followed by a 10-week follow-up (detraining) period. The exercise program is designed to improve lower extremity muscle power. Main outcome measures are: muscle power, gait speed, and gait biomechanics measured at baseline and after 10 weeks of training and 10 weeks of detraining. Discussion: It is expected that power training will increase leg muscle power measured by the weight lifted and by dynamometry, and these increased abilities become expressed in joint powers measured during gait. Such favorably modified powers will underlie the increase in step length, leading ultimately to a faster walking speed. POGS will increase our basic understanding of the biomechanical mechanisms of how power training improves gait speed in old adults with moderate levels of mobility disabilities. (C) 2016 S. Karger AG, Basel}, language = {en} } @article{BenOthmanChaouachiChaouachietal.2019, author = {Ben Othman, Aymen and Chaouachi, Anis and Chaouachi, Mehdi and Makhlouf, Issam and Farthing, Jonathan P. and Granacher, Urs and Behm, David George}, title = {Dominant and nondominant leg press training induce similar contralateral and ipsilateral limb training adaptations with children}, series = {Applied Physiology, Nutrition, and Metabolism}, volume = {44}, journal = {Applied Physiology, Nutrition, and Metabolism}, number = {9}, publisher = {NRC Research Press}, address = {Ottawa}, issn = {1715-5312}, doi = {10.1139/apnm-2018-0766}, pages = {973 -- 984}, year = {2019}, abstract = {Cross-education has been extensively investigated with adults. Adult studies report asymmetrical cross-education adaptations predominately after dominant limb training. The objective of the study was to examine unilateral leg press (LP) training of the dominant or nondominant leg on contralateral and ipsilateral strength and balance measures. Forty-two youth (10-13 years) were placed (random allocation) into a dominant (n = 15) or nondominant (n = 14) leg press training group or nontraining control (n = 13). Experimental groups trained 3 times per week for 8 weeks and were tested pre-/post-training for ipsilateral and contralateral 1-repetition maximum (RM) horizontal LP, maximum voluntary isometric contraction (MVIC) of knee extensors (KE) and flexors (KF), countermovement jump (CMJ), triple hop test (THT), MVIC strength of elbow flexors (EF) and handgrip, as well as the stork and Y balance tests. Both dominant and nondominant LP training significantly (p < 0.05) increased both ipsilateral and contralateral lower body strength (LP 1RM (dominant: 59.6\%-81.8\%; nondominant: 59.5\%-96.3\%), KE MVIC (dominant: 12.4\%-18.3\%; nondominant: 8.6\%-18.6\%), KF MVIC (dominant: 7.9\%-22.3\%; nondominant: nonsignificant-3.8\%), and power (CMJ: dominant: 11.1\%-18.1\%; nondominant: 7.7\%-16.6\%)). The exception was that nondominant LP training demonstrated a nonsignificant change with the contralateral KF MVIC. Other significant improvements were with nondominant LP training on ipsilateral EF 1RM (6.2\%) and THT (9.6\%). There were no significant changes with EF and handgrip MVIC. The contralateral leg stork balance test was impaired following dominant LP training. KF MVIC exhibited the only significant relative post-training to pretraining (post-test/pre-test) ratio differences between dominant versus nondominant LP cross-education training effects. In conclusion, children exhibit symmetrical cross-education or global training adaptations with unilateral training of dominant or nondominant upper leg.}, language = {en} } @article{NegraChaabeneSammoudetal.2017, author = {Negra, Yassine and Chaabene, Helmi and Sammoud, Senda and Bouguezzi, Raja and Abbes, Mohamed Aymen and Hachana, Younes and Granacher, Urs}, title = {Effects of Plyometric Training on Physical Fitness in Prepuberal Soccer Athletes}, series = {International journal of sports medicine}, volume = {38}, journal = {International journal of sports medicine}, publisher = {Thieme}, address = {Stuttgart}, issn = {0172-4622}, doi = {10.1055/s-0042-122337}, pages = {370 -- 377}, year = {2017}, abstract = {This study aimed at examining the effects of plyometric training on stable (SPT) vs. unstable (UPT) surfaces on physical fitness in prepuberal soccer players. Male athletes were randomly assigned to SPT (n = 18; age = 12.7 +/- 0.2 years) or UPT (n = 16; age = 12.2 +/- 0.5 years). Both groups conducted 3 regular soccer training sessions per week combined with either 2 SPT or UPT sessions. Assessment of jumping ability (countermovement jump [CMJ], and standing long jump [SLJ]), speed (10-m, 20-m, 30-m sprint), agility (Illinois agility test [IAT]), and balance (stable [SSBT], unstable [USBT] stork balance test; stable [SYBT], unstable [UYBT] Y balance test) was conducted pre-and post-training. An ANCO-VA model was used to test for between-group differences (SPT vs. UPT) at post-test using baseline values as covariates. No significant differences were found for CMJ height (p > 0.05, d = 0.54), SLJ (p > 0.05; d = 0.81), 10-m, 20-m, and 30-m sprint performances (p > 0.05, d = 0.00-0.24), IAT (p > 0.05, d = 0.48), and dynamic balance (SYBT and UYBT, both p > 0.05, d = 0.39, 0.08, respectively). Statistically significant between-group differences were detected for the USBT (p < 0.01, d = 1.86) and the SSBT (p < 0.01, d = 1.75) in favor of UPT. Following 8 weeks of SPT or UPT in prepuberal athletes, similar performance levels were observed in both groups for measures of jumping ability, speed, dynamic balance, and agility. However, if the goal is to additionally enhance static balance, UPT has an advantage over SPT.}, language = {en} } @article{WiesmeierDalinWehrleetal.2017, author = {Wiesmeier, Isabella K. and Dalin, Daniela and Wehrle, Anja and Granacher, Urs and Muehlbauer, Thomas and Dietterle, J{\"o}rg and Weiller, Cornelius and Gollhofer, Albert and Maurer, Christoph}, title = {Balance training enhances vestibular function and reduces overactive proprioceptive feedback in elderly}, series = {Frontiers in aging neuroscience}, volume = {9}, journal = {Frontiers in aging neuroscience}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1663-4365}, doi = {10.3389/fnagi.2017.00273}, pages = {13}, year = {2017}, abstract = {Objectives: Postural control in elderly people is impaired by degradations of sensory, motor, and higher-level adaptive mechanisms. Here, we characterize the effects of a progressive balance training programon these postural control impairments using a brain network model based on system identification techniques. Methods and Material: We analyzed postural control of 35 healthy elderly subjects and compared findings to data from 35 healthy young volunteers. Eighteen elderly subjects performed a 10 week balance training conducted twice per week. Balance training was carried out in static and dynamic movement states, on support surfaces with different elastic compliances, under different visual conditions and motor tasks. Postural control was characterized by spontaneous sway and postural reactions to pseudorandom anterior-posterior tilts of the support surface. Data were interpreted using a parameter identification procedure based on a brain network model. Conclusion: Balance training reduced overactive proprioceptive feedback and restored vestibular orientation in elderly. Based on the assumption of a linear deterioration of postural control across the life span, the training effect can be extrapolated as a juvenescence of 10 years. This study points to a considerable benefit of a continuous balance training in elderly, even without any sensorimotor deficits.}, language = {en} } @article{PrieskeDempsLesinskietal.2017, author = {Prieske, Olaf and Demps, Marie and Lesinski, Melanie and Granacher, Urs}, title = {Combined Effects of Fatigue and Surface Instability on Jump Biomechanics in Elite Athletes}, series = {International journal of sports medicine}, volume = {38}, journal = {International journal of sports medicine}, publisher = {Thieme}, address = {Stuttgart}, issn = {0172-4622}, doi = {10.1055/s-0043-111894}, pages = {781 -- 790}, year = {2017}, abstract = {The present study aimed to examine the effects of fatigue and surface instability on kinetic and kinematic jump performance measures. Ten female and 10 male elite volleyball players (18 +/- 2 years) performed repetitive vertical double-leg box jumps until failure. Pre and post fatigue, jump height/performance index, ground reaction force and knee flexion/valgus angles were assessed during drop and countermovement jumps on stable and unstable surfaces. Fatigue, surface condition, and sex resulted in significantly lower drop jump performance and ground reaction force (p0.031, 1.1d3.5). Additionally, drop jump knee flexion angles were significantly lower following fatigue (p=0.006, d=1.5). A significant fatiguexsurfacexsex interaction (p=0.020, d=1.2) revealed fatigue-related decrements in drop jump peak knee flexion angles under unstable conditions and in men only. Knee valgus angles were higher on unstable compared to stable surfaces during drop jumps and in females compared to males during drop and countermovement jumps (p0.054, 1.0d1.1). Significant surfacexsex interactions during countermovement jumps (p=0.002, d=1.9) indicated that knee valgus angles at onset of ground contact were significantly lower on unstable compared to stable surfaces in males but higher in females. Our findings revealed that fatigue and surface instability resulted in sex-specific knee motion strategies during jumping in elite volleyball players.}, language = {en} } @misc{BehmYoungWhittenetal.2017, author = {Behm, David George and Young, James D. and Whitten, Joseph H. D. and Reid, Jonathan C. and Quigley, Patrick J. and Low, Jonathan and Li, Yimeng and Lima, Camila D. and Hodgson, Daniel D. and Chaouachi, Anis and Prieske, Olaf and Granacher, Urs}, title = {Effectiveness of Traditional Strength vs. Power Training on Muscle Strength, Power and Speed with Youth: A Systematic Review and Meta-Analysis}, series = {Frontiers in physiology}, volume = {8}, journal = {Frontiers in physiology}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-042X}, doi = {10.3389/fphys.2017.00423}, pages = {37}, year = {2017}, abstract = {Numerous national associations and multiple reviews have documented the safety and efficacy of strength training for children and adolescents. The literature highlights the significant training-induced increases in strength associated with youth strength training. However, the effectiveness of youth strength training programs to improve power measures is not as clear. This discrepancy may be related to training and testing specificity. Most prior youth strength training programs emphasized lower intensity resistance with relatively slow movements. Since power activities typically involve higher intensity, explosive-like contractions with higher angular velocities (e.g., plyometrics), there is a conflict between the training medium and testing measures. This meta-analysis compared strength (e.g., training with resistance or body mass) and power training programs (e.g., plyometric training) on proxies of muscle strength, power, and speed. A systematic literature search using a Boolean Search Strategy was conducted in the electronic databases PubMed, SPORT Discus, Web of Science, and Google Scholar and revealed 652 hits. After perusal of title, abstract, and full text, 107 studies were eligible for inclusion in this systematic review and meta-analysis. The meta-analysis showed small to moderate magnitude changes for training specificity with jump measures. In other words, power training was more effective than strength training for improving youth jump height. For sprint measures, strength training was more effective than power training with youth. Furthermore, strength training exhibited consistently large magnitude changes to lower body strength measures, which contrasted with the generally trivial, small and moderate magnitude training improvements of power training upon lower body strength, sprint and jump measures, respectively. Maturity related inadequacies in eccentric strength and balance might influence the lack of training specificity with the unilateral landings and propulsions associated with sprinting. Based on this meta-analysis, strength training should be incorporated prior to power training in order to establish an adequate foundation of strength for power training activities.}, language = {en} } @article{GschwindBridenbaughReinhardetal.2017, author = {Gschwind, Yves J. and Bridenbaugh, Stephanie A. and Reinhard, Sarah and Granacher, Urs and Monsch, Andreas U. and Kressig, Reto W.}, title = {Ginkgo biloba special extract LI 1370 improves dual-task walking in patients with MCI: a randomised, double-blind, placebo-controlled exploratory study}, series = {Aging clinical and experimental research}, volume = {29}, journal = {Aging clinical and experimental research}, publisher = {Springer}, address = {New York}, issn = {1594-0667}, doi = {10.1007/s40520-016-0699-y}, pages = {609 -- 619}, year = {2017}, abstract = {Background In patients with mild cognitive impairment (MCI), gait instability, particularly in dual-task situations, has been associated with impaired executive function and an increased fall risk. Ginkgo biloba extract (GBE) could be an effective mean to improve gait stability. Aims This study investigated the effect of GBE on spatiotemporal gait parameters of MCI patients while walking under single and dual-task conditions. Methods Fifty patients aged 50-85 years with MCI and associated dual-task-related gait impairment participated in this randomised, double-blind, placebo-controlled, exploratory phase IV drug trial. Intervention group (IG) patients received GBE (Symfona (R) forte 120 mg) twice-daily for 6 months while control group (CG) patients received placebo capsules. A 6-month open-label phase with identical GBE dosage followed. Gait was quantified at months 0, 3, 6 and 12. Results After 6 months, dual-task-related cadence increased in the IG compared to the CG (p = 0.019, d = 0.71). No significant changes, but GBE-associated numerical non-significant trends were found after 6-month treatment for dual-task-related gait velocity and stride time variability. Discussion Findings suggest that 120 mg of GBE twice-daily for at least 6 months may improve dual-task-related gait performance in patients with MCI. Conclusions The observed gait improvements add to the understanding of the self-reported unspecified improvements among MCI patients when treated with standardised GBE.}, language = {en} } @article{NegraChaabeneHammamietal.2016, author = {Negra, Yassine and Chaabene, Helmi and Hammami, Mehrez and Hachana, Younes and Granacher, Urs}, title = {EFFECTS OF HIGH-VELOCITY RESISTANCE TRAINING ON ATHLETIC PERFORMANCE IN PREPUBERAL MALE SOCCER ATHLETES}, series = {Journal of strength and conditioning research : the research journal of the NSCA}, volume = {30}, journal = {Journal of strength and conditioning research : the research journal of the NSCA}, publisher = {Wiley-Blackwell}, address = {Philadelphia}, issn = {1064-8011}, doi = {10.1519/JSC.0000000000001433}, pages = {3290 -- 3297}, year = {2016}, abstract = {The aim of this study was to assess the effectiveness of a 12-week in-season low-to-moderate load high-velocity resistance training (HVRT) in addition to soccer training as compared with soccer training only on proxies of athletic performance in prepubertal soccer players. Twenty-four male soccer players performed 2 different protocols: (a) regular soccer training with 5 sessions per week (n = 11; age = 12.7 +/- 0.3 years) and (b) regular soccer training with 3 sessions per week and HVRT with 2 sessions per week (n = 13; age = 12.8 +/- 0.2 years). The outcome measures included tests for the assessment of muscle strength (e.g., 1 repetition maximum [1RM] half-squat tests), jump ability (e.g., countermovement jump, squat jump [SJ], standing long jump [SLJ], and multiple 5-bound tests [MB5s]), linear speed (e.g., 5-, 10-, 20-, and 30-m sprint tests), and change of direction (e.g., T-test and Illinois change of direction test). Results revealed significant group 3 test interactions for the SJ test (p <= 0.05, d = 0.59) and the SLJ test (p < 0.01, d = 0.83). Post hoc tests illustrated significant pre-post changes in the HVRT group (SJ: Delta 22\%, p < 0.001, d = 1.26; SLJ: Delta 15\%, p < 0.001, d = 1.30) but not in the control group. In addition, tendencies toward significant interaction effects were found for the 1RM half-squat (p = 0.08, d = 0.54) and the 10-m sprint test (p = 0.06, d = 0.57). Significant pre-post changes were found for both parameters in the HVRT group only (1RM: Delta 25\%, p < 0.001, d = 1.23; 10-m sprint: Delta 7\%, p < 0.0001, d = 1.47). In summary, in-season low-to-moderate load HVRT conducted in combination with regular soccer training is a safe and feasible intervention that has positive effects on maximal strength, vertical and horizontal jump and sprint performance as compared with soccer training only.}, language = {en} } @article{GrabowYoungByrneetal.2017, author = {Grabow, Lena and Young, James D. and Byrne, Jeannette M. and Granacher, Urs and Behm, David George}, title = {Unilateral Rolling of the Foot did not Affect Non-Local Range of Motion or Balance}, series = {Journal of sports science \& medicine}, volume = {16}, journal = {Journal of sports science \& medicine}, publisher = {Department of Sports Medicine, Medical Faculty of Uludag University}, address = {Bursa}, issn = {1303-2968}, pages = {209 -- 218}, year = {2017}, abstract = {Non-local or crossover (contralateral and non-stretched muscles) increases in range-of-motion (ROM) and balance have been reported following rolling of quadriceps, hamstrings and plantar flexors. Since there is limited information regarding plantar sole (foot) rolling effects, the objectives of this study were to determine if unilateral foot rolling would affect ipsilateral and contralateral measures of ROM and balance in young healthy adults. A randomized within-subject design was to examine non-local effects of unilateral foot rolling on ipsilateral and contralateral limb ankle dorsiflexion ROM and a modified sit-and-reachtest (SRT). Static balance was also tested during a 30 s single leg stance test. Twelve participants performed three bouts of 60 s unilateral plantar sole rolling using a roller on the dominant foot with 60 s rest intervals between sets. ROM and balance measures were assessed in separate sessions at pre-intervention, immediately and 10 minutes post-intervention. To evaluate repeated measures effects, two SRT pre-tests were implemented. Results demonstrated that the second pre-test SRT was 6.6\% higher than the first pre-test (p = 0.009, d = 1.91). There were no statistically significant effects of foot rolling on any measures immediately or 10 min post-test. To conclude, unilateral foot rolling did not produce statistically significant increases in ipsilateral or contralateral dorsiflexion or SRT ROM nor did it affect postural sway. Our statistically non-significant findings might be attributed to a lower degree of roller-induced afferent stimulation due to the smaller volume of myofascia and muscle compared to prior studies. Furthermore, ROM results from studies utilizing a single pre-test without a sufficient warm-up should be viewed critically.}, language = {en} } @article{JafamezhadgeroShadMajlesietal.2017, author = {Jafamezhadgero, Amir Ali and Shad, Morteza Madadi and Majlesi, Mahdi and Granacher, Urs}, title = {A comparison of running kinetics in children with and without genu varus: A cross sectional study}, series = {PLoS one}, volume = {12}, journal = {PLoS one}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0185057}, pages = {15}, year = {2017}, abstract = {Introduction Varus knee alignment has been identified as a risk factor for the progression of medial knee osteoarthritis. However, the underlying mechanisms have not been elucidated yet in children. Thus, the aims of the present study were to examine differences in ground reaction forces, loading rate, impulses, and free moment values during running in children with and without genu varus. Methods Thirty-six boys aged 9-14 volunteered to participate in this study. They were divided in two age-matched groups (genu varus versus healthy controls). Body weight adjusted three dimensional kinetic data (Fx, Fy, Fz) were collected during running at preferred speed using two Kistler force plates for the dominant and non-dominant limb. Results Individuals with knee genu varus produced significantly higher (p = .01; d = 1.09; 95\%) body weight adjusted ground reaction forces in the lateral direction (Fx) of the dominant limb compared to controls. On the non-dominant limb, genu varus patients showed significantly higher body weight adjusted ground reaction forces values in the lateral (p = .01; d = 1.08; 86\%) and medial (p < .001; d = 1.55; 102\%) directions (Fx). Further, genu varus patients demonstrated 55\% and 36\% greater body weight adjusted loading rates in the dominant (p < .001; d = 2.09) and non-dominant (p < .001; d = 1.02) leg, respectively. No significant between-group differences were observed for adjusted free moment values (p>.05). Discussion Higher mediolateral ground reaction forces and vertical loading rate amplitudes in boys with genu varus during running at preferred running speed may accelerate the development of progressive joint degeneration in terms of the age at knee osteoarthritis onset. Therefore, practitioners and therapists are advised to conduct balance and strength training programs to improve lower limb alignment and mediolateral control during dynamic movements.}, language = {en} } @article{LesinskiPrieskeBeurskensetal.2017, author = {Lesinski, Melanie and Prieske, Olaf and Beurskens, Rainer and Behm, David George and Granacher, Urs}, title = {Effects of drop height and surface instability on neuromuscular activation during drop jumps}, series = {Scandinavian journal of medicine \& science in sports}, volume = {27}, journal = {Scandinavian journal of medicine \& science in sports}, publisher = {Wiley}, address = {Hoboken}, issn = {0905-7188}, doi = {10.1111/sms.12732}, pages = {1090 -- 1098}, year = {2017}, abstract = {The purpose of this study was to examine whether drop height-induced changes in leg muscle activity during drop jumps (DJ) are additionally modulated by surface condition. Twenty-four healthy participants (23.7 +/- 1.8years) performed DJs on a force plate on stable, unstable, and highly unstable surfaces using different drop heights (i.e., 20cm, 40cm, 60cm). Electromyographic (EMG) activity of soleus (SOL), gastrocnemius (GM), tibialis anterior (TA) muscles and coactivation of TA/SOL and TA/GM were analyzed for time intervals 100ms prior to ground contact (preactivation) and 30-60ms after ground contact [short latency response (SLR)]. Increasing drop heights resulted in progressively increased SOL and GM activity during preactivation and SLR (P<0.01; 1.01 d 5.34) while TA/SOL coactivation decreased (P<0.05; 0.51 d 3.01). Increasing surface instability produced decreased activities during preactivation (GM) and SLR (GM, SOL) (P<0.05; 1.36 d 4.30). Coactivation increased during SLR (P<0.05; 1.50 d 2.58). A significant drop heightxsurface interaction was observed for SOL during SLR. Lower SOL activity was found on unstable compared to stable surfaces for drop heights 40cm (P<0.05; 1.25 d 2.12). Findings revealed that instability-related changes in activity of selected leg muscles are minimally affected by drop height.}, language = {en} } @article{HammamiGranacherMakhloufetal.2016, author = {Hammami, Raouf and Granacher, Urs and Makhlouf, Issam and Behm, David George and Chaouachi, Anis}, title = {SEQUENCING EFFECTS OF BALANCE AND PLYOMETRIC TRAINING ON PHYSICAL PERFORMANCE IN YOUTH SOCCER ATHLETES}, series = {Journal of strength and conditioning research : the research journal of the NSCA}, volume = {30}, journal = {Journal of strength and conditioning research : the research journal of the NSCA}, publisher = {Elsevier}, address = {Philadelphia}, issn = {1064-8011}, doi = {10.1519/JSC.0000000000001425}, pages = {3278 -- 3289}, year = {2016}, abstract = {Balance training may have a preconditioning effect on subsequent power training with youth. There are no studies examining whether the sequencing of balance and plyometric training has additional training benefits. The objective was to examine the effect of sequencing balance and plyometric training on the performance of 12- to 13-year-old athletes. Twenty-four young elite soccer players trained twice per week for 8 weeks either with an initial 4 weeks of balance training followed by 4 weeks of plyometric training (BPT) or 4 weeks of plyometric training proceeded by 4 weeks of balance training (PBT). Testing was conducted pre- and posttraining and included medicine ball throw; horizontal and vertical jumps; reactive strength; leg stiffness; agility; 10-, 20-, and 30-m sprints; Standing Stork balance test; and Y-Balance test. Results indicated that BPT provided significantly greater improvements with reactive strength index, absolute and relative leg stiffness, triple hop test, and a trend for the Y-Balance test (p = 0.054) compared with PBT. Although all other measures had similar changes for both groups, the average relative improvement for the BPT was 22.4\% (d = 1.5) vs. 15.0\% (d = 1.1) for the PBT. BPT effect sizes were greater with 8 of 13 measures. In conclusion, although either sequence of BPT or PBT improved jumping, hopping, sprint acceleration, and Standing Stork and Y-Balance, BPT initiated greater training improvements in reactive strength index, absolute and relative leg stiffness, triple hop test, and the Y-Balance test. BPT may provide either similar or superior performance enhancements compared with PBT.}, language = {en} } @article{PrieskeMuehlbauerKruegeretal.2015, author = {Prieske, Olaf and M{\"u}hlbauer, Thomas and Kr{\"u}ger, Tom and Kibele, Armin and Behm, David George and Granacher, Urs}, title = {Role of the trunk during drop jumps on stable and unstable surfaces}, series = {European journal of applied physiology}, volume = {115}, journal = {European journal of applied physiology}, number = {1}, publisher = {Springer}, address = {New York}, issn = {1439-6319}, doi = {10.1007/s00421-014-3004-9}, pages = {139 -- 146}, year = {2015}, abstract = {The present study investigated associations between trunk muscle strength, jump performance, and lower limb kinematics during drop jumps on stable and unstable surfaces. Next to this behavioral approach, correlations were also computed on a neuromuscular level between trunk and leg muscle activity during the same test conditions. Twenty-nine healthy and physically active subjects (age 23 +/- A 3 years) were enrolled in this study. Peak isokinetic torque (PIT) of the trunk flexors and extensors was assessed separately on an isokinetic device. In addition, tests included drop jumps (DJ) on a force plate under stable and unstable (i.e., balance pad on top of the force plate) surfaces. Lower limb kinematics as well as electromyographic activity of selected trunk and leg muscles were analyzed. Significant positive but small correlations (0.50 a parts per thousand currency sign r a parts per thousand currency sign 0.66, p < 0.05) were detected between trunk extensor PIT and athletic performance measures (i.e., DJ height, DJ performance index), irrespective of surface condition. Further, significant negative but small correlation coefficients were examined between trunk extensor PIT and knee valgus motion under stable and unstable surface conditions (-0.48 a parts per thousand currency sign r a parts per thousand currency sign -0.45, p < 0.05). In addition, significant positive but small correlations (0.45 a parts per thousand currency sign r a parts per thousand currency sign 0.68, p < 0.05) were found between trunk and leg muscle activity, irrespective of surface condition. Behavioral and neuromuscular data from this study indicate that, irrespective of the surface condition (i.e., jumping on stable or unstable ground), the trunk plays a minor role for leg muscle performance/activity during DJ. This implies only limited effects of trunk muscle strengthening on jump performance in the stretch-shortening cycle.}, language = {en} } @article{MuehlbauerPabstGranacheretal.2017, author = {M{\"u}hlbauer, Thomas and Pabst, Jan and Granacher, Urs and Buesch, Dirk}, title = {Validity of the jump-and-reach test in subelite adolescent handball players}, series = {Journal of strength and conditioning research : the research journal of the NSCA}, volume = {31}, journal = {Journal of strength and conditioning research : the research journal of the NSCA}, publisher = {Lippincott Williams \& Wilkins}, address = {Philadelphia}, issn = {1064-8011}, doi = {10.1519/JSC.0000000000001607}, pages = {1282 -- 1289}, year = {2017}, language = {en} } @misc{LesinskiMuehlbauerGranacher2017, author = {Lesinski, Melanie and M{\"u}hlbauer, Thomas and Granacher, Urs}, title = {Concurrent validity of the Gyko inertial sensor system for the assessment of vertical jump height in female sub-elite youth soccer players}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400967}, pages = {9}, year = {2017}, abstract = {Background: The aim of the present study was to verify concurrent validity of the Gyko inertial sensor system for the assessment of vertical jump height. - Methods: Nineteen female sub-elite youth soccer players (mean age: 14.7 ± 0.6 years) performed three trials of countermovement (CMJ) and squat jumps (SJ), respectively. Maximal vertical jump height was simultaneously quantified with the Gyko system, a Kistler force-plate (i.e., gold standard), and another criterion device that is frequently used in the field, the Optojump system. - Results: Compared to the force-plate, the Gyko system determined significant systematic bias for mean CMJ (-0.66 cm, p < 0.01, d = 1.41) and mean SJ (-0.91 cm, p < 0.01, d = 1.69) height. Random bias was ± 3.2 cm for CMJ and ± 4.0 cm for SJ height and intraclass correlation coefficients (ICCs) were "excellent" (ICC = 0.87 for CMJ and 0.81 for SJ). Compared to the Optojump device, the Gyko system detected a significant systematic bias for mean CMJ (0.55 cm, p < 0.05, d = 0.94) but not for mean SJ (0.39 cm) height. Random bias was ± 3.3 cm for CMJ and ± 4.2 cm for SJ height and ICC values were "excellent" (ICC = 0.86 for CMJ and 0.82 for SJ). - Conclusion: Consequently, apparatus specific regression equations were provided to estimate true vertical jump height for the Kistler force-plate and the Optojump device from Gyko-derived data. Our findings indicate that the Gyko system cannot be used interchangeably with a Kistler force-plate and the Optojump device in trained individuals. It is suggested that practitioners apply the correction equations to estimate vertical jump height for the force-plate and the Optojump system from Gyko-derived data.}, language = {en} } @article{SaeterbakkenStienAndersenetal.2022, author = {Saeterbakken, Atle H. and Stien, Nicolay and Andersen, Vidar and Scott, Suzanne and Cumming, Kristoffer T. and Behm, David G. and Granacher, Urs and Prieske, Olaf}, title = {The effects of trunk muscle training on physical fitness and sport-specific performance in young and adult athletes}, series = {Sports medicine}, volume = {52}, journal = {Sports medicine}, number = {7}, publisher = {Springer}, address = {Northcote}, issn = {0112-1642}, doi = {10.1007/s40279-021-01637-0}, pages = {1599 -- 1622}, year = {2022}, abstract = {Background The role of trunk muscle training (TMT) for physical fitness (e.g., muscle power) and sport-specific performance measures (e.g., swimming time) in athletic populations has been extensively examined over the last decades. However, a recent systematic review and meta-analysis on the effects of TMT on measures of physical fitness and sport-specific performance in young and adult athletes is lacking. Objective To aggregate the effects of TMT on measures of physical fitness and sport-specific performance in young and adult athletes and identify potential subject-related moderator variables (e.g., age, sex, expertise level) and training-related programming parameters (e.g., frequency, study length, session duration, and number of training sessions) for TMT effects. Data Sources A systematic literature search was conducted with PubMed, Web of Science, and SPORTDiscus, with no date restrictions, up to June 2021. Study Eligibility Criteria Only controlled trials with baseline and follow-up measures were included if they examined the effects of TMT on at least one measure of physical fitness (e.g., maximal muscle strength, change-of-direction speed (CODS)/agility, linear sprint speed) and sport-specific performance (e.g., throwing velocity, swimming time) in young or adult competitive athletes at a regional, national, or international level. The expertise level was classified as either elite (competing at national and/or international level) or regional (i.e., recreational and sub-elite). Study Appraisal and Synthesis Methods The methodological quality of TMT studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. A random-effects model was used to calculate weighted standardized mean differences (SMDs) between intervention and active control groups. Additionally, univariate sub-group analyses were independently computed for subject-related moderator variables and training-related programming parameters. Results Overall, 31 studies with 693 participants aged 11-37 years were eligible for inclusion. The methodological quality of the included studies was 5 on the PEDro scale. In terms of physical fitness, there were significant, small-to-large effects of TMT on maximal muscle strength (SMD = 0.39), local muscular endurance (SMD = 1.29), lower limb muscle power (SMD = 0.30), linear sprint speed (SMD = 0.66), and CODS/agility (SMD = 0.70). Furthermore, a significant and moderate TMT effect was found for sport-specific performance (SMD = 0.64). Univariate sub-group analyses for subject-related moderator variables revealed significant effects of age on CODS/agility (p = 0.04), with significantly large effects for children (SMD = 1.53, p = 0.002). Further, there was a significant effect of number of training sessions on muscle power and linear sprint speed (p <= 0.03), with significant, small-to-large effects of TMT for > 18 sessions compared to <= 18 sessions (0.45 <= SMD <= 0.84, p <= 0.003). Additionally, session duration significantly modulated TMT effects on linear sprint speed, CODS/agility, and sport-specific performance (p <= 0.05). TMT with session durations <= 30 min resulted in significant, large effects on linear sprint speed and CODS/agility (1.66 <= SMD <= 2.42, p <= 0.002), whereas session durations > 30 min resulted in significant, large effects on sport-specific performance (SMD = 1.22, p = 0.008). Conclusions Our findings indicate that TMT is an effective means to improve selected measures of physical fitness and sport-specific performance in young and adult athletes.
Independent sub-group analyses suggest that TMT has the potential to improve CODS/agility, but only in children. Additionally, more (> 18) and/or shorter duration (<= 30 min) TMT sessions appear to be more effective for improving lower limb muscle power, linear sprint speed, and CODS/agility in young or adult competitive athletes.}, language = {en} } @misc{KibeleClassenMuehlbaueretal.2014, author = {Kibele, Armin and Classen, Claudia and M{\"u}hlbauer, Thomas and Granacher, Urs and Behm, David George}, title = {Metastability in plyometric training on unstable surfaces}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {606}, issn = {1866-8364}, doi = {10.25932/publishup-42901}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429013}, pages = {13}, year = {2014}, abstract = {Background In the past, plyometric training (PT) has been predominantly performed on stable surfaces. The purpose of this pilot study was to examine effects of a 7-week lower body PT on stable vs. unstable surfaces. This type of exercise condition may be denoted as metastable equilibrium. Methods Thirty-three physically active male sport science students (age: 24.1 ± 3.8 years) were randomly assigned to a PT group (n = 13) exercising on stable (STAB) and a PT group (n = 20) on unstable surfaces (INST). Both groups trained countermovement jumps, drop jumps, and practiced a hurdle jump course. In addition, high bar squats were performed. Physical fitness tests on stable surfaces (hexagonal obstacle test, countermovement jump, hurdle drop jump, left-right hop, dynamic and static balance tests, and leg extension strength) were used to examine the training effects. Results Significant main effects of time (ANOVA) were found for the countermovement jump, hurdle drop jump, hexagonal test, dynamic balance, and leg extension strength. A significant interaction of time and training mode was detected for the countermovement jump in favor of the INST group. No significant improvements were evident for either group in the left-right hop and in the static balance test. Conclusions These results show that lower body PT on unstable surfaces is a safe and efficient way to improve physical performance on stable surfaces.}, language = {en} } @article{LesinskiPrieskeDempsetal.2016, author = {Lesinski, Melanie and Prieske, Olaf and Demps, Marie and Granacher, Urs}, title = {Effects of fatigue and surface instability on neuromuscular performance during jumping}, series = {Der Schmerz : Organ der Deutschen Gesellschaft zum Studium des Schmerzes, der {\~A}-sterreichischen Schmerzgesellschaft und der Deutschen Interdisziplin{\~A}\iren Vereinigung f{\~A}¼r Schmerztherapie}, volume = {26}, journal = {Der Schmerz : Organ der Deutschen Gesellschaft zum Studium des Schmerzes, der {\~A}-sterreichischen Schmerzgesellschaft und der Deutschen Interdisziplin{\~A}\iren Vereinigung f{\~A}¼r Schmerztherapie}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0905-7188}, doi = {10.1111/sms.12548}, pages = {1140 -- 1150}, year = {2016}, abstract = {It has previously been shown that fatigue and unstable surfaces affect jump performance. However, the combination thereof is unresolved. Thus, the purpose of this study was to examine the effects of fatigue and surface instability on jump performance and leg muscle activity. Twenty elite volleyball players (18 +/- 2 years) performed repetitive vertical double-leg box jumps until failure. Before and after a fatigue protocol, jump performance (i.e., jump height) and electromyographic activity of selected lower limb muscles were recorded during drop jumps (DJs) and countermovement jumps (CMJs) on a force plate on stable and unstable surfaces (i.e., balance pad on top of force plate). Jump performance (3-7\%; P < 0.05; 1.14 <= d <= 2.82), and muscle activity (2-27\%; P < 0.05; 0.59 <= d <= 3.13) were lower following fatigue during DJs and CMJs, and on unstable compared with stable surfaces during DJs only (jump performance: 8\%; P < 0.01; d = 1.90; muscle activity: 9-25\%; P < 0.05; 1.08 <= d <= 2.54). No statistically significant interactions of fatigue by surface condition were observed. Our findings revealed that fatigue impairs neuromuscular performance during DJs and CMJs in elite volleyball players, whereas surface instability affects neuromuscular DJ performance only. Absent fatigue x surface interactions indicate that fatigue-induced changes in jump performance are similar on stable and unstable surfaces in jump-trained athletes.}, language = {en} } @misc{WickLeegerAschmannMonnetal.2017, author = {Wick, Kristin and Leeger-Aschmann, Claudia S. and Monn, Nico D. and Radtke, Thomas and Ott, Laura V. and Rebholz, Cornelia E. and Cruz, Sergio and Gerber, Natalie and Schmutz, Einat A. and Puder, Jardena J. and Munsch, Simone and Kakebeeke, Tanja H. and Jenni, Oskar G. and Granacher, Urs and Kriemler, Susi}, title = {Interventions to promote fundamental movement skills in childcare and kindergarten}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {702}, issn = {1866-8364}, doi = {10.25932/publishup-43546}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-435463}, pages = {26}, year = {2017}, abstract = {Background Proficiency in fundamental movement skills (FMS) lays the foundation for being physically active and developing more complex motor skills. Improving these motor skills may provide enhanced opportunities for the development of a variety of perceptual, social, and cognitive skills. Objective The objective of this systematic review and meta-analysis was to assess the effects of FMS interventions on actual FMS, targeting typically developing young children. Method Searches in seven databases (CINAHL, Embase, MEDLINE, PsycINFO, PubMed, Scopus, Web of Science) up to August 2015 were completed. Trials with children (aged 2-6 years) in childcare or kindergarten settings that applied FMS-enhancing intervention programs of at least 4 weeks and meeting the inclusion criteria were included. Standardized data extraction forms were used. Risk of bias was assessed using a standard scoring scheme (Effective Public Health Practice Project-Quality Assessment Tool for Quantitative Studies [EPHPP]). We calculated effects on overall FMS, object control and locomotor subscales (OCS and LMS) by weighted standardized mean differences (SMDbetween) using random-effects models. Certainty in training effects was evaluated using GRADE (Grading of Recommendations Assessment, Development, and Evaluation System). Results Thirty trials (15 randomized controlled trials and 15 controlled trials) involving 6126 preschoolers (aged 3.3-5.5 years) revealed significant differences among groups in favor of the intervention group (INT) with small-to-large effects on overall FMS (SMDbetween 0.46), OCS (SMDbetween 1.36), and LMS (SMDbetween 0.94). Our certainty in the treatment estimates based on GRADE is very low. Conclusions Although there is relevant effectiveness of programs to improve FMS proficiency in healthy young children, they need to be interpreted with care as they are based on low-quality evidence and immediate post-intervention effects without long-term follow-up.}, language = {en} } @article{BeurskensSteinbergAntoniewiczetal.2016, author = {Beurskens, Rainer and Steinberg, Fabian and Antoniewicz, Franziska and Wolff, Wanja and Granacher, Urs}, title = {Neural Correlates of Dual-Task Walking}, series = {Neural plasticity}, volume = {2016}, journal = {Neural plasticity}, publisher = {Hindawi}, address = {New York}, doi = {10.1155/2016/8032180}, pages = {1 -- 9}, year = {2016}, abstract = {Walking while concurrently performing cognitive and/or motor interference tasks is the norm rather than the exception during everyday life and there is evidence from behavioral studies that it negatively affects human locomotion. However, there is hardly any information available regarding the underlying neural correlates of single- and dual-task walking. We had 12 young adults (23.8 ± 2.8 years) walk while concurrently performing a cognitive interference (CI) or a motor interference (MI) task. Simultaneously, neural activation in frontal, central, and parietal brain areas was registered using a mobile EEG system. Results showed that the MI task but not the CI task affected walking performance in terms of significantly decreased gait velocity and stride length and significantly increased stride time and tempo-spatial variability. Average activity in alpha and beta frequencies was significantly modulated during both CI and MI walking conditions in frontal and central brain regions, indicating an increased cognitive load during dual-task walking. Our results suggest that impaired motor performance during dual-task walking is mirrored in neural activation patterns of the brain. This finding is in line with established cognitive theories arguing that dual-task situations overstrain cognitive capabilities resulting in motor performance decrements.}, language = {en} } @misc{BeurskensMuehlbauerGranacher2015, author = {Beurskens, Rainer and M{\"u}hlbauer, Thomas and Granacher, Urs}, title = {Association of dual-task walking performance and leg muscle quality in healthy children}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-75100}, pages = {7}, year = {2015}, abstract = {Background Previous literature mainly introduced cognitive functions to explain performance decrements in dual-task walking, i.e., changes in dual-task locomotion are attributed to limited cognitive information processing capacities. In this study, we enlarge existing literature and investigate whether leg muscular capacity plays an additional role in children's dual-task walking performance. Methods To this end, we had prepubescent children (mean age: 8.7 ± 0.5 years, age range: 7-9 years) walk in single task (ST) and while concurrently conducting an arithmetic subtraction task (DT). Additionally, leg lean tissue mass was assessed. Results Findings show that both, boys and girls, significantly decrease their gait velocity (f = 0.73), stride length (f = 0.62) and cadence (f = 0.68) and increase the variability thereof (f = 0.20-0.63) during DT compared to ST. Furthermore, stepwise regressions indicate that leg lean tissue mass is closely associated with step time and the variability thereof during DT (R2 = 0.44, p = 0.009). These associations between gait measures and leg lean tissue mass could not be observed for ST (R2 = 0.17, p = 0.19). Conclusion We were able to show a potential link between leg muscular capacities and DT walking performance in children. We interpret these findings as evidence that higher leg muscle mass in children may mitigate the impact of a cognitive interference task on DT walking performance by inducing enhanced gait stability.}, language = {en} } @article{WerfelliHammamiSelmietal.2021, author = {Werfelli, Hanen and Hammami, Raouf and Selmi, Mohamed Amine and Selmi, Walid and Gabrilo, Goran and Clark, Cain C. T. and Duncan, Michael and Sekulic, Damir and Granacher, Urs and Rebai, Haithem}, title = {Acute Effects of Different Plyometric and Strength Exercises on Balance Performance in Youth Weightlifters}, series = {Frontiers in Physiology}, volume = {12}, journal = {Frontiers in Physiology}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-042X}, doi = {10.3389/fphys.2021.716981}, pages = {9}, year = {2021}, abstract = {Background: High-intensity muscle actions have the potential to temporarily improve the performance which has been denoted as postactivation performance enhancement. Objectives: This study determined the acute effects of different stretch-shortening (fast vs. low) and strength (dynamic vs. isometric) exercises executed during one training session on subsequent balance performance in youth weightlifters. Materials and Methods: Sixteen male and female young weightlifters, aged 11.3±0.6years, performed four strength exercise conditions in randomized order, including dynamic strength (DYN; 3 sets of 3 repetitions of 10 RM) and isometric strength exercises (ISOM; 3 sets of maintaining 3s of 10 RM of back-squat), as well as fast (FSSC; 3 sets of 3 repetitions of 20-cm drop-jumps) and slow (SSSC; 3 sets of 3 hurdle jumps over a 20-cm obstacle) stretch-shortening cycle protocols. Balance performance was tested before and after each of the four exercise conditions in bipedal stance on an unstable surface (i.e., BOSU ball with flat side facing up) using two dependent variables, i.e., center of pressure surface area (CoP SA) and velocity (CoP V). Results: There was a significant effect of time on CoP SA and CoP V [F(1,60)=54.37, d=1.88, p<0.0001; F(1,60)=9.07, d=0.77, p=0.003]. In addition, a statistically significant effect of condition on CoP SA and CoP V [F(3,60)=11.81, d=1.53, p<0.0001; F(3,60)=7.36, d=1.21, p=0.0003] was observed. Statistically significant condition-by-time interactions were found for the balance parameters CoP SA (p<0.003, d=0.54) and CoP V (p<0.002, d=0.70). Specific to contrast analysis, all specified hypotheses were tested and demonstrated that FSSC yielded significantly greater improvements than all other conditions in CoP SA and CoP V [p<0.0001 (d=1.55); p=0.0004 (d=1.19), respectively]. In addition, FSSC yielded significantly greater improvements compared with the two conditions for both balance parameters [p<0.0001 (d=2.03); p<0.0001 (d=1.45)]. Conclusion: Fast stretch-shortening cycle exercises appear to be more effective to improve short-term balance performance in young weightlifters. Due to the importance of balance for overall competitive achievement in weightlifting, it is recommended that young weightlifters implement dynamic plyometric exercises in the fast stretch-shortening cycle during the warm-up to improve their balance performance.}, language = {en} } @article{BeurskensMuehlbauerGranacher2015, author = {Beurskens, Rainer and M{\"u}hlbauer, Thomas and Granacher, Urs}, title = {Association of dual-task walking performance and leg muscle quality in healthy children}, series = {BMC pediatrics}, volume = {15}, journal = {BMC pediatrics}, number = {2}, publisher = {BioMed Central}, address = {London}, issn = {1471-2431}, doi = {10.1186/s12887-015-0317-8}, year = {2015}, abstract = {Background Previous literature mainly introduced cognitive functions to explain performance decrements in dual-task walking, i.e., changes in dual-task locomotion are attributed to limited cognitive information processing capacities. In this study, we enlarge existing literature and investigate whether leg muscular capacity plays an additional role in children's dual-task walking performance. Methods To this end, we had prepubescent children (mean age: 8.7 ± 0.5 years, age range: 7-9 years) walk in single task (ST) and while concurrently conducting an arithmetic subtraction task (DT). Additionally, leg lean tissue mass was assessed. Results Findings show that both, boys and girls, significantly decrease their gait velocity (f = 0.73), stride length (f = 0.62) and cadence (f = 0.68) and increase the variability thereof (f = 0.20-0.63) during DT compared to ST. Furthermore, stepwise regressions indicate that leg lean tissue mass is closely associated with step time and the variability thereof during DT (R2 = 0.44, p = 0.009). These associations between gait measures and leg lean tissue mass could not be observed for ST (R2 = 0.17, p = 0.19). Conclusion We were able to show a potential link between leg muscular capacities and DT walking performance in children. We interpret these findings as evidence that higher leg muscle mass in children may mitigate the impact of a cognitive interference task on DT walking performance by inducing enhanced gait stability.}, language = {en} } @misc{NevillNegraMyersetal.2021, author = {Nevill, Alan M. and Negra, Yassine and Myers, Tony D. and Duncan, Michael J. and Chaabene, Helmi and Granacher, Urs}, title = {Are Early or Late Maturers Likely to Be Fitter in the General Population?}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {695}, issn = {1866-8364}, doi = {10.25932/publishup-48992}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-489928}, pages = {18}, year = {2021}, abstract = {The present study aims to identify the optimal body-size/shape and maturity characteristics associated with superior fitness test performances having controlled for body-size, sex, and chronological-age differences. The sample consisted of 597 Tunisian children (396 boys and 201 girls) aged 8 to 15 years. Three sprint speeds recorded at 10, 20 and 30 m; two vertical and two horizontal jump tests; a change-of-direction and a handgrip-strength tests, were assessed during physical-education classes. Allometric modelling was used to identify the benefit of being an early or late maturer. Findings showed that being tall and light is the ideal shape to be successful at most physical fitness tests, but the height-to-weight "shape" ratio seems to be test-dependent. Having controlled for body-size/shape, sex, and chronological age, the model identified maturity-offset as an additional predictor. Boys who go earlier/younger through peak-height-velocity (PHV) outperform those who go at a later/older age. However, most of the girls' physical-fitness tests peaked at the age at PHV and decline thereafter. Girls whose age at PHV was near the middle of the age range would appear to have an advantage compared to early or late maturers. These findings have important implications for talent scouts and coaches wishing to recruit children into their sports/athletic clubs.}, language = {en} } @article{BehmAlizadehDruryetal.2021, author = {Behm, David G. and Alizadeh, Shahab and Drury, Ben and Granacher, Urs and Moran, Jason}, title = {Non-local acute stretching effects on strength performance in healthy young adults}, series = {European journal of applied physiology}, volume = {121}, journal = {European journal of applied physiology}, number = {6}, publisher = {Springer}, address = {Berlin ; Heidelberg}, issn = {1439-6319}, doi = {10.1007/s00421-021-04657-w}, pages = {1517 -- 1529}, year = {2021}, abstract = {Background Static stretching (SS) can impair performance and increase range of motion of a non-exercised or non-stretched muscle, respectively. An underdeveloped research area is the effect of unilateral stretching on non-local force output. Objective The objective of this review was to describe the effects of unilateral SS on contralateral, non-stretched, muscle force and identify gaps in the literature. Methods A systematic literature search following preferred reporting items for systematic review and meta-analyses Protocols guidelines was performed according to prescribed inclusion and exclusion criteria. Weighted means and ranges highlighted the non-local force output response to unilateral stretching. The physiotherapy evidence database scale was used to assess study risk of bias and methodological quality. Results Unilateral stretching protocols from six studies involved 6.3 +/- 2 repetitions of 36.3 +/- 7.4 s with 19.3 +/- 5.7 s recovery between stretches. The mean stretch-induced force deficits exhibited small magnitude effect sizes for both the stretched (-6.7 +/- 7.1\%, d = -0.35: 0.01 to -1.8) and contralateral, non-stretched, muscles (-4.0 +/- 4.9\%, d = , 0.22: 0.08 to 1.1). Control measures exhibited trivial deficits. Conclusion The limited literature examining non-local effects of prolonged SS revealed that both the stretched and contralateral, non-stretched, limbs of young adults demonstrate small magnitude force deficits. However, the frequency of studies with these effects were similar with three measures demonstrating deficits, and four measures showing trivial changes. These results highlight the possible global (non-local) effects of prolonged SS. Further research should investigate effects of lower intensity stretching, upper versus lower body stretching, different age groups, incorporate full warm-ups, and identify predominant mechanisms among others.}, language = {en} } @misc{LesinskiMuehlbauerBueschetal.2014, author = {Lesinski, Melanie and M{\"u}hlbauer, Thomas and Buesch, Dirk and Granacher, Urs}, title = {Effects of complex training on strength and speed performance in athletes: A systematic review effects of complex training on athletic performance}, series = {Sportverletzung, Sportschaden : Grundlagen, Pr{\"a}vention, Rehabilitation}, volume = {28}, journal = {Sportverletzung, Sportschaden : Grundlagen, Pr{\"a}vention, Rehabilitation}, number = {2}, publisher = {Thieme}, address = {Stuttgart}, issn = {0932-0555}, doi = {10.1055/s-0034-1366145}, pages = {85 -- 107}, year = {2014}, abstract = {Background: Post-activation potentiation (PAP) can elicit acute performance enhancements in variables of strength, power, and speed. However, it is unresolved whether the frequent integration of PAP eliciting conditioning activities in training (i.e., complex training) results in long-term adaptations. In this regard, it is of interest to know whether complex training results in larger performance enhancements as compared to more traditional and isolated training regimens (e. g., resistance training). Thus, this systematic literature review summarises the current state of the art regarding the effects of complex training on measures of strength, power, and speed in recreational, subelite, and elite athletes. Further, it provides information on training volume and intensities that proved to be effective. Methods: Our literature search included the electronic databases Pubmed, SportDiscus, and Web of Science (1995 to September 2013). In total, 17 studies met the inclusionary criteria for review. Ten studies examined alternating complex training and 7 studies sequenced complex training. Results: Our findings indicated small to large effects for both alternating complex training (countermovement jump height: +7.4 \% [ESd = -0.43]; squat jump height: +9.8 \% [ESd = -0.66]; sprint time: -2.4\% [ESd = 0.63]) and sequenced complex training (countermovement jump height: +6.0 \% [ESd = -0.83]; squat jump height: +11.9\% [ESd = -0.97], sprint time: -0.7\% [ESd = 0.52]) in measures of power and speed. As compared to more traditional training regimens, alternating and sequenced complex training showed only small effects in measures of strength, power, and speed. A more detailed analysis of alternating complex training revealed larger effects in countermovement jump height in recreational athletes (+9.7\% [ESd = -0.57]) as compared to subelite and elite athletes (+2.7\% [ESd = -0.15]). Based on the relevant and currently available literature, missing data (e.g., time for rest interval) and diverse information regarding training volume and intensity do not allow us to establish evidence-based dose-response relations for complex training. Conclusion: Complex training represents an effective training regimen for athletes if the goal is to enhance strength, power, and speed. Studies with high methodological quality have to be conducted in the future to elucidate whether complex training is less, similar, or even more effective compared to more traditional training regimens. Finally, it should be clarified whether alternated and/or sequenced conditioning activities implemented in complex training actually elicit acute PAP effects.}, language = {de} } @misc{GolleMuehlbauerWicketal.2015, author = {Golle, Kathleen and M{\"u}hlbauer, Thomas and Wick, Ditmar and Granacher, Urs}, title = {Physical Fitness Percentiles of German Children Aged 9-12 Years}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-86613}, year = {2015}, abstract = {Background Generating percentile values is helpful for the identification of children with specific fitness characteristics (i.e., low or high fitness level) to set appropriate fitness goals (i.e., fitness/health promotion and/or long-term youth athlete development). Thus, the aim of this longitudinal study was to assess physical fitness development in healthy children aged 9-12 years and to compute sex- and age-specific percentile values. Methods Two-hundred and forty children (88 girls, 152 boys) participated in this study and were tested for their physical fitness. Physical fitness was assessed using the 50-m sprint test (i.e., speed), the 1-kg ball push test, the triple hop test (i.e., upper- and lower- extremity muscular power), the stand-and-reach test (i.e., flexibility), the star run test (i.e., agility), and the 9-min run test (i.e., endurance). Age- and sex-specific percentile values (i.e., P10 to P90) were generated using the Lambda, Mu, and Sigma method. Adjusted (for change in body weight, height, and baseline performance) age- and sex-differences as well as the interactions thereof were expressed by calculating effect sizes (Cohen's d). Results Significant main effects of Age were detected for all physical fitness tests (d = 0.40-1.34), whereas significant main effects of Sex were found for upper-extremity muscular power (d = 0.55), flexibility (d = 0.81), agility (d = 0.44), and endurance (d = 0.32) only. Further, significant Sex by Age interactions were observed for upper-extremity muscular power (d = 0.36), flexibility (d = 0.61), and agility (d = 0.27) in favor of girls. Both, linear and curvilinear shaped curves were found for percentile values across the fitness tests. Accelerated (curvilinear) improvements were observed for upper-extremity muscular power (boys: 10-11 yrs; girls: 9-11 yrs), agility (boys: 9-10 yrs; girls: 9-11 yrs), and endurance (boys: 9-10 yrs; girls: 9-10 yrs). Tabulated percentiles for the 9-min run test indicated that running distances between 1,407-1,507 m, 1,479-1,597 m, 1,423-1,654 m, and 1,433-1,666 m in 9- to 12-year-old boys and 1,262-1,362 m, 1,329-1,434 m, 1,392-1,501 m, and 1,415-1,526 m in 9- to 12-year-old girls correspond to a "medium" fitness level (i.e., P40 to P60) in this population. Conclusions The observed differences in physical fitness development between boys and girls illustrate that age- and sex-specific maturational processes might have an impact on the fitness status of healthy children. Our statistical analyses revealed linear (e.g., lower-extremity muscular power) and curvilinear (e.g., agility) models of fitness improvement with age which is indicative of timed and capacity-specific fitness development pattern during childhood. Lastly, the provided age- and sex-specific percentile values can be used by coaches for talent identification and by teachers for rating/grading of children's motor performance.}, language = {en} } @misc{GranacherKissLueder2018, author = {Granacher, Urs and Kiss, Rainer and L{\"u}der, Benjamin}, title = {Single- and Dual-Task Balance Training Are Equally Effective in Youth}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {432}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-411679}, pages = {12}, year = {2018}, abstract = {Due to maturation of the postural control system and secular declines in motor performance, adolescents experience deficits in postural control during standing and walking while concurrently performing cognitive interference tasks. Thus, adequately designed balance training programs may help to counteract these deficits. While the general effectiveness of youth balance training is well-documented, there is hardly any information available on the specific effects of single-task (ST) versus dual-task (DT) balance training. Therefore, the objectives of this study were (i) to examine static/dynamic balance performance under ST and DT conditions in adolescents and (ii) to study the effects of ST versus DT balance training on static/dynamic balance under ST and DT conditions in adolescents. Twenty-eight healthy girls and boys aged 12-13 years were randomly assigned to either 8 weeks of ST or DT balance training. Before and after training, postural sway and spatio-temporal gait parameters were registered under ST (standing/walking only) and DT conditions (standing/walking while concurrently performing an arithmetic task). At baseline, significantly slower gait speed (p < 0.001, d = 5.1), shorter stride length (p < 0.001, d = 4.8), and longer stride time (p < 0.001, d = 3.8) were found for DT compared to ST walking but not standing. Training resulted in significant pre-post decreases in DT costs for gait velocity (p < 0.001, d = 3.1), stride length (-45\%, p < 0.001, d = 2.4), and stride time (-44\%, p < 0.01, d = 1.9). Training did not induce any significant changes (p > 0.05, d = 0-0.1) in DT costs for all parameters of secondary task performance during standing and walking. Training produced significant pre-post increases (p = 0.001; d = 1.47) in secondary task performance while sitting. The observed increase was significantly greater for the ST training group (p = 0.04; d = 0.81). For standing, no significant changes were found over time irrespective of the experimental group. We conclude that adolescents showed impaired DT compared to ST walking but not standing. ST and DT balance training resulted in significant and similar changes in DT costs during walking. Thus, there appears to be no preference for either ST or DT balance training in adolescents.}, language = {en} } @misc{SariatiHammamiZouhaletal., author = {Sariati, Dorsaf and Hammami, Raouf and Zouhal, Hassane and Clark, Cain Craig Truman and Nebigh, Ammar and Chtara, Moktar and Chortane, Sabri Gaied and Hackney, Anthony C. and Souissi, Nizar and Granacher, Urs and Ben Ounis, Omar}, title = {Improvement of Physical Performance Following a 6 Week Change-of-Direction Training Program in Elite Youth Soccer Players of Different Maturity Levels}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, publisher = {Universit{\"a}t Potsdam}, address = {Potsdam}, issn = {1866-8364}, doi = {10.25932/publishup-54101}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-541019}, pages = {1 -- 8}, abstract = {Background: Change-of-direction (CoD) is a necessary physical ability of a field sport and may vary in youth players according to their maturation status. Objectives: The aim of this study is: to compare the effectiveness of a 6-week CoD training intervention on dynamic balance (CS-YBT), horizontal jump (5JT), speed (10 and 30-m linear sprint times), CoD with (15 m-CoD + B) and without (15 m-CoD) the ball, in youth male soccer players at different levels of maturity [pre- and post-peak height velocity (PHV)]. Materials and Methods: Thirty elite male youth soccer players aged 10-17 years from the Tunisian first division participated in this study. The players were divided into pre- (G1, n = 15) and post-PHV (G2, n = 15) groups. Both groups completed a similar 6-week training program with two sessions per week of four CoD exercises. All players completed the following tests before and after intervention: CS-YBT; 5 JT; 10, 30, and 15 m-CoD; and 15 m-CoD + B, and data were analyzed using ANCOVA. Results: All 30 players completed the study according to the study design and methodology. Adherence rate was 100\% across all groups, and no training or test-related injuries were reported. Pre-PHV and post-PHV groups showed significant amelioration post-intervention for all dependent variables (after test > before test; p < 0.01, d = 0.09-1.51). ANOVA revealed a significant group × time interaction only for CS-YBT (F = 4.45; p < 0.04; η2 = 0.14), 5JT (F = 6.39; p < 0.02; η2 = 0.18), and 15 m-CoD (F = 7.88; p < 0.01; η2 = 0.22). CS-YBT, 5JT, and 15 m-CoD improved significantly in the post-PHV group (+ 4.56\%, effect size = 1.51; + 4.51\%, effect size = 1.05; and -3.08\%, effect size = 0.51, respectively), more than the pre-PHV group (+ 2.77\%, effect size = 0.85; + 2.91\%, effect size = 0.54; and -1.56\%, effect size = 0.20, respectively). Conclusion: The CoD training program improved balance, horizontal jump, and CoD without the ball in male preadolescent and adolescent soccer players, and this improvement was greater in the post-PHV players. The maturity status of the athletes should be considered when programming CoD training for soccer players.}, language = {en} } @misc{ElAshkerChaabeneNegraetal.2018, author = {El-Ashker, Said and Chaabene, Helmi and Negra, Yassine and Prieske, Olaf and Granacher, Urs}, title = {Cardio-Respiratory endurance responses following a simulated 3 x 3 minutes amateur boxing contest in elite level boxers}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, number = {675}, issn = {1866-8364}, doi = {10.25932/publishup-47233}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-472338}, pages = {10}, year = {2018}, abstract = {This study aimed at examining physiological responses (i.e., oxygen uptake [VO2] and heart rate [HR]) to a semi-contact 3 x 3-min format, amateur boxing combat simulation in elite level male boxers. Eleven boxers aged 21.4 +/- 2.1 years (body height 173.4 +/- 3.7, body mass 74.9 +/- 8.6 kg, body fat 12.1 +/- 1.9, training experience 5.7 +/- 1.3 years) volunteered to participate in this study. They performed a maximal graded aerobic test on a motor-driven treadmill to determine maximum oxygen uptake (VO2max), oxygen uptake (VO2AT) and heart rate (HRAT) at the anaerobic threshold, and maximal heart rate (HRmax). Additionally, VO2 and peak HR (HRpeak) were recorded following each boxing round. Results showed no significant differences between VO2max values derived from the treadmill running test and VO2 outcomes of the simulated boxing contest (p > 0.05, d = 0.02 to 0.39). However, HRmax and HRpeak recorded from the treadmill running test and the simulated amateur boxing contest, respectively, displayed significant differences regardless of the boxing round (p < 0.01, d = 1.60 to 3.00). In terms of VO2 outcomes during the simulated contest, no significant between-round differences were observed (p = 0.19, d = 0.17 to 0.73). Irrespective of the boxing round, the recorded VO2 was >90\% of the VO2max. Likewise, HRpeak observed across the three boxing rounds were >= 90\% of the HRmax. In summary, the simulated 3 x 3-min amateur boxing contest is highly demanding from a physiological standpoint. Thus, coaches are advised to systematically monitor internal training load for instance through rating of perceived exertion to optimize training-related adaptations and to prevent boxers from overreaching and/or overtraining.}, language = {en} } @misc{GranacherLacroixMuehlbaueretal.2017, author = {Granacher, Urs and Lacroix, Andre and M{\"u}hlbauer, Thomas and Roettger, Katrin and Gollhofer, Albert}, title = {Effects of core instability strength training on trunk muscle strength, spinal mobility, dynamic balance and functional mobility in older adults}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-399994}, pages = {9}, year = {2017}, abstract = {Background: Age-related postural misalignment, balance deficits and strength/power losses are associated with impaired functional mobility and an increased risk of falling in seniors. Core instability strength training (CIT) involves exercises that are challenging for both trunk muscles and postural control and may thus have the potential to induce benefits in trunk muscle strength, spinal mobility and balance performance. Objective: The objective was to investigate the effects of CIT on measures of trunk muscle strength, spinal mobility, dynamic balance and functional mobility in seniors. Methods: Thirty-two older adults were randomly assigned to an intervention group (INT; n = 16, aged 70.8 +/- 4.1 years) that conducted a 9-week progressive CIT or to a control group (n = 16, aged 70.2 +/- 4.5 years). Maximal isometric strength of the trunk flexors/extensors/lateral flexors (right, left)/rotators (right, left) as well as of spinal mobility in the sagittal and the coronal plane was measured before and after the intervention program. Dynamic balance (i.e. walking 10 m on an optoelectric walkway, the Functional Reach test) and functional mobility (Timed Up and Go test) were additionally tested. Results: Program compliance was excellent with participants of the INT group completing 92\% of the training sessions. Significant group x test interactions were found for the maximal isometric strength of the trunk flexors (34\%, p < 0.001), extensors (21\%, p < 0.001), lateral flexors (right: 48\%, p < 0.001; left: 53\%, p < 0.001) and left rotators (42\%, p < 0.001) in favor of the INT group. Further, training-related improvements were found for spinal mobility in the sagittal (11\%, p < 0.001) and coronal plane (11\%, p = 0.06) directions, for stride velocity (9\%, p < 0.05), the coefficient of variation in stride velocity (31\%, p < 0.05), the Functional Reach test (20\%, p < 0.05) and the Timed Up and Go test (4\%, p < 0.05) in favor of the INT group. Conclusion: CIT proved to be a feasible exercise program for seniors with a high adherence rate. Age-related deficits in measures of trunk muscle strength, spinal mobility, dynamic balance and functional mobility can be mitigated by CIT. This training regimen could be used as an adjunct or even alternative to traditional balance and/or resistance training.}, language = {en} } @misc{GranacherMuehlbauerBridenbaughetal.2017, author = {Granacher, Urs and M{\"u}hlbauer, Thomas and Bridenbaugh, Stephanie A. and Wolf, Madeleine and Roth, Ralf and Gschwind, Yves and Wolf, Irene and Mata, Rui and Kressig, Reto W.}, title = {Effects of a salsa dance training on balance and strength performance in older adults}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-399962}, pages = {8}, year = {2017}, abstract = {Background: Deficits in static and particularly dynamic postural control and force production have frequently been associated with an increased risk of falling in older adults. Objective: The objectives of this study were to investigate the effects of salsa dancing on measures of static/dynamic postural control and leg extensor power in seniors. Methods: Twenty-eight healthy older adults were randomly assigned to an intervention group (INT, n = 14, age 71.6 +/- 5.3 years) to conduct an 8-week progressive salsa dancing programme or a control group (CON, n = 14, age 68.9 +/- 4.7 years). Static postural control was measured during one-legged stance on a balance platform and dynamic postural control was obtained while walking on an instrumented walkway. Leg extensor power was assessed during a countermovement jump on a force plate. Results: Programme compliance was excellent with participants of the INT group completing 92.5\% of the dancing sessions. A tendency towards an improvement in the selected measures of static postural control was observed in the INT group as compared to the CON group. Significant group X test interactions were found for stride velocity, length and time. Post hoc analyses revealed significant increases in stride velocity and length, and concomitant decreases in stride time. However, salsa dancing did not have significant effects on various measures of gait variability and leg extensor power. Conclusion: Salsa proved to be a safe and feasible exercise programme for older adults accompanied with a high adherence rate. Age-related deficits in measures of static and particularly dynamic postural control can be mitigated by salsa dancing in older adults. High physical activity and fitness/mobility levels of our participants could be responsible for the nonsignificant findings in gait variability and leg extensor power.}, language = {en} } @misc{MuehlbauerBesemerWehrleetal.2017, author = {M{\"u}hlbauer, Thomas and Besemer, Carmen and Wehrle, Anja and Gollhofer, Albert and Granacher, Urs}, title = {Relationship between strength, power and balance performance in seniors}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-399970}, pages = {9}, year = {2017}, abstract = {Background: Deficits in strength, power and balance represent important intrinsic risk factors for falls in seniors. Objective: The purpose of this study was to investigate the relationship between variables of lower extremity muscle strength/power and balance, assessed under various task conditions. Methods: Twenty-four healthy and physically active older adults (mean age: 70 8 5 years) were tested for their isometric strength (i.e. maximal isometric force of the leg extensors) and muscle power (i.e. countermovement jump height and power) as well as for their steady-state (i.e. unperturbed standing, 10-meter walk), proactive (i.e. Timed Up \& Go test, Functional Reach Test) and reactive (i.e. perturbed standing) balance. Balance tests were conducted under single (i.e. standing or walking alone) and dual task conditions (i.e. standing or walking plus cognitive and motor interference task). Results: Significant positive correlations were found between measures of isometric strength and muscle power of the lower extremities (r values ranged between 0.608 and 0.720, p < 0.01). Hardly any significant associations were found between variables of strength, power and balance (i.e. no significant association in 20 out of 21 cases). Additionally, no significant correlations were found between measures of steady-state, proactive and reactive balance or balance tests performed under single and dual task conditions (all p > 0.05). Conclusion: The predominately nonsignificant correlations between different types of balance imply that balance performance is task specific in healthy and physically active seniors. Further, strength, power and balance as well as balance under single and dual task conditions seem to be independent of each other and may have to be tested and trained complementarily}, language = {en} } @article{JafarnezhadgeroFatollahiAmirzadehetal.2019, author = {Jafarnezhadgero, Amir Ali and Fatollahi, Amir and Amirzadeh, Nasrin and Siahkouhian, Marefat and Granacher, Urs}, title = {Ground Reaction Forces and Muscle Activity While Walking on Sand versus Stable Ground in Individuals with Pronated Feet Compared with Healthy Controls}, series = {PloS ONe}, volume = {9}, journal = {PloS ONe}, number = {14}, publisher = {PloS ONe}, address = {San Francisco, California}, issn = {1932-6203}, doi = {10.1371/journal.pone.0223219}, pages = {15}, year = {2019}, abstract = {Background Sand is an easy-to-access, cost-free resource that can be used to treat pronated feet (PF). Therefore, the aims of this study were to contrast the effects of walking on stable ground versus walking on sand on ground reaction forces (GRFs) and electromyographic (EMG) activity of selected lower limb muscles in PF individuals compared with healthy controls. Methods Twenty-nine controls aged 22.2±2.5 years and 30 PF individuals aged 22.2±1.9 years were enrolled in this study. Participants walked at preferred speed and in randomized order over level ground and sand. A force plate was included in the walkway to collect GRFs. Muscle activities were recorded using EMG system. Results No statistically significant between-group differences were found in preferred walking speed when walking on stable ground (PF: 1.33±0.12 m/s; controls: 1.35±0.14 m/s; p = 0.575; d = 0.15) and sand (PF: 1.19±0.11 m/s; controls: 1.23±0.18 m/s; p = 0.416; d = 0.27). Irrespective of the group, walking on sand (1.21±0.15 m/s) resulted in significantly lower gait speed compared with stable ground walking (1.34±0.13 m/s) (p<0.001; d = 0.93). Significant main effects of "surface" were found for peak posterior GRFs at heel contact, time to peak for peak lateral GRFs at heel contact, and peak anterior GRFs during push-off (p<0.044; d = 0.27-0.94). Pair-wise comparisons revealed significantly smaller peak posterior GRFs at heel contact (p = 0.005; d = 1.17), smaller peak anterior GRFs during push-off (p = 0.001; d = 1.14), and time to peak for peak lateral GRFs (p = 0.044; d = 0.28) when walking on sand. No significant main effects of "group" were observed for peak GRFs and their time to peak (p>0.05; d = 0.06-1.60). We could not find any significant group by surface interactions for peak GRFs and their time to peak. Significant main effects of "surface" were detected for anterior-posterior impulse and peak positive free moment amplitude (p<0.048; d = 0.54-0.71). Pair-wise comparisons revealed a significantly larger peak positive free moment amplitude (p = 0.010; d = 0.71) and a lower anterior-posterior impulse (p = 0.048; d = 0.38) when walking on sand. We observed significant main effects of "group" for the variable loading rate (p<0.030; d = 0.59). Pair-wise comparisons revealed significantly lower loading rates in PF compared with controls (p = 0.030; d = 0.61). Significant group by surface interactions were observed for the parameter peak positive free moment amplitude (p<0.030; d = 0.59). PF individuals exhibited a significantly lower peak positive free moment amplitude (p = 0.030, d = 0.41) when walking on sand. With regards to EMG, no significant main effects of "surface", main effects of "group", and group by surface interactions were observed for the recorded muscles during the loading and push-off phases (p>0.05; d = 0.00-0.53). Conclusions The observed lower velocities during walking on sand compared with stable ground were accompanied by lower peak positive free moments during the push-off phase and loading rates during the loading phase. Our findings of similar lower limb muscle activities during walking on sand compared with stable ground in PF together with lower free moment amplitudes, vertical loading rates, and lower walking velocities on sand may indicate more relative muscle activity on sand compared with stable ground. This needs to be verified in future studies.}, language = {en} } @misc{BeurskensMuehlbauerGranacheretal.2015, author = {Beurskens, Rainer and M{\"u}hlbauer, Thomas and Granacher, Urs and Gollhofer, Albert and Cardinale, Marco}, title = {Effects of heavy-resistance strength and balance training on unilateral and bilateral leg strength performance in old adults}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-73448}, pages = {13}, year = {2015}, abstract = {The term "bilateral deficit" (BLD) has been used to describe a reduction in performance during bilateral contractions when compared to the sum of identical unilateral contractions. In old age, maximal isometric force production (MIF) decreases and BLD increases indicating the need for training interventions to mitigate this impact in seniors. In a cross-sectional approach, we examined age-related differences in MIF and BLD in young (age: 20-30 years) and old adults (age: >65 years). In addition, a randomized-controlled trial was conducted to investigate training-specific effects of resistance vs. balance training on MIF and BLD of the leg extensors in old adults. Subjects were randomly assigned to resistance training (n = 19), balance training (n = 14), or a control group (n = 20). Bilateral heavy-resistance training for the lower extremities was performed for 13 weeks (3 × / week) at 80\% of the one repetition maximum. Balance training was conducted using predominately unilateral exercises on wobble boards, soft mats, and uneven surfaces for the same duration. Pre- and post-tests included uni- and bilateral measurements of maximal isometric leg extension force. At baseline, young subjects outperformed older adults in uni- and bilateral MIF (all p < .001; d = 2.61-3.37) and in measures of BLD (p < .001; d = 2.04). We also found significant increases in uni- and bilateral MIF after resistance training (all p < .001, d = 1.8-5.7) and balance training (all p < .05, d = 1.3-3.2). In addition, BLD decreased following resistance (p < .001, d = 3.4) and balance training (p < .001, d = 2.6). It can be concluded that both training regimens resulted in increased MIF and decreased BLD of the leg extensors (HRT-group more than BAL-group), almost reaching the levels of young adults.}, language = {en} } @misc{WerfelliHammamiSelmietal.2021, author = {Werfelli, Hanen and Hammami, Raouf and Selmi, Mohamed Amine and Selmi, Walid and Gabrilo, Goran and Clark, Cain C. T. and Duncan, Michael and Sekulic, Damir and Granacher, Urs and Rebai, Haithem}, title = {Acute Effects of Different Plyometric and Strength Exercises on Balance Performance in Youth Weightlifters}, series = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Humanwissenschaftliche Reihe}, issn = {1866-8364}, doi = {10.25932/publishup-54310}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-543109}, pages = {11}, year = {2021}, abstract = {Background: High-intensity muscle actions have the potential to temporarily improve the performance which has been denoted as postactivation performance enhancement. Objectives: This study determined the acute effects of different stretch-shortening (fast vs. low) and strength (dynamic vs. isometric) exercises executed during one training session on subsequent balance performance in youth weightlifters. Materials and Methods: Sixteen male and female young weightlifters, aged 11.3±0.6years, performed four strength exercise conditions in randomized order, including dynamic strength (DYN; 3 sets of 3 repetitions of 10 RM) and isometric strength exercises (ISOM; 3 sets of maintaining 3s of 10 RM of back-squat), as well as fast (FSSC; 3 sets of 3 repetitions of 20-cm drop-jumps) and slow (SSSC; 3 sets of 3 hurdle jumps over a 20-cm obstacle) stretch-shortening cycle protocols. Balance performance was tested before and after each of the four exercise conditions in bipedal stance on an unstable surface (i.e., BOSU ball with flat side facing up) using two dependent variables, i.e., center of pressure surface area (CoP SA) and velocity (CoP V). Results: There was a significant effect of time on CoP SA and CoP V [F(1,60)=54.37, d=1.88, p<0.0001; F(1,60)=9.07, d=0.77, p=0.003]. In addition, a statistically significant effect of condition on CoP SA and CoP V [F(3,60)=11.81, d=1.53, p<0.0001; F(3,60)=7.36, d=1.21, p=0.0003] was observed. Statistically significant condition-by-time interactions were found for the balance parameters CoP SA (p<0.003, d=0.54) and CoP V (p<0.002, d=0.70). Specific to contrast analysis, all specified hypotheses were tested and demonstrated that FSSC yielded significantly greater improvements than all other conditions in CoP SA and CoP V [p<0.0001 (d=1.55); p=0.0004 (d=1.19), respectively]. In addition, FSSC yielded significantly greater improvements compared with the two conditions for both balance parameters [p<0.0001 (d=2.03); p<0.0001 (d=1.45)]. Conclusion: Fast stretch-shortening cycle exercises appear to be more effective to improve short-term balance performance in young weightlifters. Due to the importance of balance for overall competitive achievement in weightlifting, it is recommended that young weightlifters implement dynamic plyometric exercises in the fast stretch-shortening cycle during the warm-up to improve their balance performance.}, language = {en} }