TY - JOUR A1 - Hortobagyi, Tibor A1 - Granacher, Urs A1 - Fernandez-del-Olmo, Miguel A1 - Howatson, Glyn A1 - Manca, Andrea A1 - Deriu, Franca A1 - Taube, Wolfgang A1 - Gruber, Markus A1 - Marquez, Gonzalo A1 - Lundbye-Jensen, Jesper A1 - Colomer-Poveda, David T1 - Functional relevance of resistance training-induced neuroplasticity in health and disease JF - Neuroscience & biobehavioral reviews : official journal of the International Behavioral Neuroscience Society N2 - Repetitive, monotonic, and effortful voluntary muscle contractions performed for just a few weeks, i.e., resistance training, can substantially increase maximal voluntary force in the practiced task and can also increase gross motor performance. The increase in motor performance is often accompanied by neuroplastic adaptations in the central nervous system. While historical data assigned functional relevance to such adaptations induced by resistance training, this claim has not yet been systematically and critically examined in the context of motor performance across the lifespan in health and disease. A review of muscle activation, brain and peripheral nerve stimulation, and imaging data revealed that increases in motor performance and neuroplasticity tend to be uncoupled, making a mechanistic link between neuroplasticity and motor performance inconclusive. We recommend new approaches, including causal mediation analytical and hypothesis-driven models to substantiate the functional relevance of resistance training-induced neuroplasticity in the improvements of gross motor function across the lifespan in health and disease. KW - Maximal voluntary contraction (MVC) KW - strength training KW - Electromyography (EMG) KW - Transcranial magnetic brain stimulation (TMS) KW - Electroencephalography (EEG) KW - Functional magnetic resonance imaging (fMRI) KW - athletic performance KW - aging KW - Parkinson's disease KW - Multiple sclerosis KW - stroke KW - directed acyclic graphs KW - causal mediation analysis Y1 - 2020 U6 - https://doi.org/10.1016/j.neubiorev.2020.12.019 SN - 0149-7634 SN - 1873-7528 VL - 122 SP - 79 EP - 91 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Pavillon, Thomas A1 - Tourny, Claire A1 - Ben Abderrahman, Abderraouf A1 - Salhi, Iyed A1 - Zouita, Sghaeir A1 - Rouissi, Mehdi A1 - Hackney, Anthony C. A1 - Granacher, Urs A1 - Zouhal, Hassane T1 - Sprint and jump performances in highly trained young soccer players of different chronological age BT - Effects of linear VS. CHANGE–OF–DIRECTION sprint training JF - Journal of Exercise Science & Fitness N2 - Objective The aim of this study was to examine the effects of two different sprint-training regimes on sprint and jump performances according to age in elite young male soccer players over the course of one soccer season. Methods Players were randomly assigned to two training groups. Group 1 performed systematic change-of-direction sprints (CODST, U19 [n = 9], U17 [n = 9], U15 [n = 10]) while group 2 conducted systematic linear sprints (LST, U19 [n = 9], U17 [n = 9], U15 [n = 9]). Training volumes were similar between groups (40 sprints per week x 30 weeks = 1200 sprints per season). Pre and post training, all players performed tests for the assessment of linear and slalom sprint speed (5-m and 10-m), countermovement jump, and maximal aerobic speed performance. Results For all physical fitness measures, the baseline-adjusted means data (ANCOVA) across the age groups showed no significant differences between LST and CODST at post (0.061 < p < 0.995; 0.0017 < d < 1.01). The analyses of baseline-adjusted means for all physical fitness measures for U15, U17, and U19 (LST vs. CODST) revealed no significant differences between LST and CODST for U15 (0.213 < p < 0.917; 0.001 < d < 0.087), U17 (0.132 < p < 0.976; 0.001 < d < 0.310), and U19 (0.300 < p < 0.999; 0.001 < d < 0.049) at post. Conclusions The results from this study showed that both, LST and CODST induced significant changes in the sprint, lower limbs power, and aerobic performances in young elite soccer players. Since no significant differences were observed between LST and CODST, the observed changes are most likely due to training and/or maturation. Therefore, more research is needed to elucidate whether CODST, LST or a combination of both is beneficial for youth soccer athletes’ performance development. KW - Football KW - Repeated sprint KW - Performance KW - Speed Y1 - 2020 U6 - https://doi.org/10.1016/j.jesf.2020.10.003 SN - 1728-869x VL - 19 IS - 2 SP - 81 EP - 90 PB - Elsevier CY - Singapore ER - TY - JOUR A1 - Lesinski, Melanie A1 - Schmelcher, Alina A1 - Herz, Michael A1 - Puta, Christian A1 - Gabriel, Holger A1 - Arampatzis, Adamantios A1 - Laube, Gunnar A1 - Büsch, Dirk A1 - Granacher, Urs T1 - Maturation-, age-, and sex-specific anthropometric and physical fitness percentiles of German elite young athletes JF - Plos One N2 - The aim of this study was to establish maturation-, age-, and sex-specific anthropometric and physical fitness percentile reference values of young elite athletes from various sports. Anthropometric (i.e., standing and sitting body height, body mass, body mass index) and physical fitness (i.e., countermovement jump, drop jump, change-of-direction speed [i.e., T-test], trunk muscle endurance [i.e., ventral Bourban test], dynamic lower limbs balance [i.e., Y-balance test], hand grip strength) of 703 male and female elite young athletes aged 8–18 years were collected to aggregate reference values according to maturation, age, and sex. Findings indicate that body height and mass were significantly higher (p<0.001; 0.95≤d≤1.74) in more compared to less mature young athletes as well as with increasing chronological age (p<0.05; 0.66≤d≤3.13). Furthermore, male young athletes were significantly taller and heavier compared to their female counterparts (p<0.001; 0.34≤d≤0.50). In terms of physical fitness, post-pubertal athletes showed better countermovement jump, drop jump, change-of-direction, and handgrip strength performances (p<0.001; 1.57≤d≤8.72) compared to pubertal athletes. Further, countermovement jump, drop jump, change-of-direction, and handgrip strength performances increased with increasing chronological age (p<0.05; 0.29≤d≤4.13). In addition, male athletes outperformed their female counterpart in the countermovement jump, drop jump, change-of-direction, and handgrip strength (p<0.05; 0.17≤d≤0.76). Significant age by sex interactions indicate that sex-specific differences were even more pronounced with increasing age. Conclusively, body height, body mass, and physical fitness increased with increasing maturational status and chronological age. Sex-specific differences appear to be larger as youth grow older. Practitioners can use the percentile values as approximate benchmarks for talent identification and development. KW - biological maturation KW - reliability KW - validity KW - performance KW - physiology KW - maturity KW - injury KW - talent Y1 - 2020 U6 - https://doi.org/10.1371/journal.pone.0237423 SN - 1932-6203 VL - 15 IS - 8 PB - Plos One CY - San Francisco, California ER - TY - JOUR A1 - Granacher, Urs A1 - Nobari, Hadi A1 - Ruivo Alves, Ana A1 - Clemente, Filipe Manuel A1 - Pérez-Gómez, Jorge A1 - Clark, Cain Craig Truman A1 - Zouhal, Hassane T1 - Associations Between Variations in Accumulated Workload and Physiological Variables in Young Male Soccer Players Over the Course of a Season JF - Frontiers in physiology N2 - This study sought to analyze the relationship between in-season training workload with changes in aerobic power (VO2max), maximum and resting heart rate (HRmax and HRrest), linear sprint medium (LSM), and short test (LSS), in soccer players younger than 16 years (under-16 soccer players). We additionally aimed to explain changes in fitness levels during the in-season through regression models, considering accumulated load, baseline levels, and peak height velocity (PHV) as predictors. Twenty-three male sub-elite soccer players aged 15.5 ± 0.2 years (PHV: 13.6 ± 0.4 years; body height: 172.7 ± 4.2 cm; body mass: 61.3 ± 5.6 kg; body fat: 13.7% ± 3.9%; VO2max: 48.4 ± 2.6 mL⋅kg–1⋅min–1), were tested three times across the season (i.e., early-season (EaS), mid-season (MiS), and end-season (EnS) for VO2max, HRmax, LSM, and LSS. Aerobic and speed variables gradually improved over the season and had a strong association with PHV. Moreover, the HRmax demonstrated improvements from EaS to EnS; however, this was more evident in the intermediate period (from EaS to MiS) and had a strong association with VO2max. Regression analysis showed significant predictions for VO2max [F(2, 20) = 8.18, p ≤ 0.001] with an R2 of 0.45. In conclusion, the meaningful variation of youth players’ fitness levels can be observed across the season, and such changes can be partially explained by the load imposed. KW - internal load KW - heart rate KW - linear sprint KW - aerobic power KW - football Y1 - 2021 U6 - https://doi.org/10.3389/fphys.2021.638180 SN - 1664-042X VL - 12 SP - 1 EP - 12 PB - Frontiers Research Foundation CY - Lausanne, Schweiz ER - TY - JOUR A1 - Azadian, Elaheh A1 - Majlesi, Mahdi A1 - Jafarnezhadgero, Amir Ali A1 - Granacher, Urs T1 - The impact of hearing loss on three-dimensional lower limb joint torques during walking in prepubertal boys JF - Journal of bodywork and movement therapies N2 - Introduction: In children, the impact of hearing loss on biomechanical gait parameters is not well understood. Thus, the objectives of this study were to examine three-dimensional lower limb joint torques in deaf compared to age-matched healthy (hearing) children while walking at preferred gait speed. Methods: Thirty prepubertal boys aged 8-14 were enrolled in this study and divided into a group with hearing loss (deaf group) and an age-matched healthy control. Three-dimensional joint torques were analyzed during barefoot walking at preferred speed using Kistler force plates and a Vicon motion capture system. Results: Findings revealed that boys with hearing loss showed lower joint torques in ankle evertors, knee flexors, abductors and internal rotators as well as in hip internal rotators in both, the dominant and non-dominant lower limbs (all p < 0.05; d = 1.23-7.00; 14-79%). Further, in the dominant limb, larger peak ankle dorsiflexor (p < 0.001; d = 1.83; 129%), knee adductor (p < 0.001; d = 3.20; 800%), and hip adductor torques (p < 0.001; d = 2.62; 350%) were found in deaf participants compared with controls. Conclusion: The observed altered lower limb torques during walking are indicative of unstable gait in children with hearing loss. More research is needed to elucidate whether physical training (e.g., balance and/or gait training) has the potential to improve walking performance in this patient group. (C) 2019 Elsevier Ltd. All rights reserved. KW - torque KW - hearing loss KW - gait KW - dominant limb KW - non-dominant limb Y1 - 2020 U6 - https://doi.org/10.1016/j.jbmt.2019.10.013 SN - 1360-8592 SN - 1532-9283 VL - 24 IS - 2 SP - 123 EP - 129 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Moran, Jason A1 - Paxton, Kevin A1 - Jones, Ben A1 - Granacher, Urs A1 - Sandercock, Gavin Rh A1 - Hope, Edward A1 - Ramirez-Campillo, Rodrigo T1 - Variable long-term developmental trajectories of short sprint speed and jumping height in English Premier League academy soccer players: an applied case study JF - Journal of sports sciences N2 - Growth and maturation affect long term physical performance, making the appraisal of athletic ability difficult. We sought to longitudinally track youth soccer players to assess the developmental trajectory of athletic performance over a 6-year period in an English Premier League academy. Age-specific z-scores were calculated for sprint and jump performance from a sample of male youth soccer players (n = 140). A case study approach was used to analyse the longitudinal curves of the six players with the longest tenure. The trajectories of the sprint times of players 1 and 3 were characterised by a marked difference in respective performance levels up until peak height velocity (PHV) when player 1 achieved a substantial increase in sprint speed and player 3 experienced a large decrease. Player 5 was consistently a better performer than player 2 until PHV when the sprint and jump performance of the former markedly decreased and he was overtaken by the latter. Fluctuations in players' physical performance can occur quickly and in drastic fashion. Coaches must be aware that suppressed, or inflated, performance could be temporary and selection and deselection decisions should not be made based on information gathered over a short time period. KW - youth KW - football KW - talent KW - running velocity KW - muscular power Y1 - 2020 U6 - https://doi.org/10.1080/02640414.2020.1792689 SN - 0264-0414 SN - 1466-447X VL - 38 IS - 22 SP - 2525 EP - 2531 PB - Routledge, Taylor & Francis Group CY - London ER - TY - JOUR A1 - Jafarnezhadgero, Amir Ali A1 - Anvari, Maryam A1 - Granacher, Urs T1 - Long-term effects of shoe mileage on ground reaction forces and lower limb muscle activities during walking in individuals with genu varus JF - Clinical biomechanics N2 - Background: Shoe mileage is an important factor that may influence the risk of sustaining injuries during walking. The aims of this study were to examine the effects of shoe mileage on ground reaction forces and activity of lower limb muscles during walking in genu varus individuals compared with controls. Methods: Fifteen healthy and 15 genu varus females received a new pair of running shoes. They were asked to wear these shoes over 6 months. Pre and post intervention, mechanical shoe testing was conducted and ground reaction forces and muscle activities of the right leg were recorded during walking at preferred gait speed. Findings: Significant group-by-time interactions were found for shoe stiffness, antero-posterior and vertical impact peak. We observed higher shoe stiffness and lower impact peaks after intervention in both groups with larger effect sizes in genu varus. Significant group-by-time interactions were identified for vastus medialis (loading phase) and rectus femoris (loading and push-off). For vastus medialis, significant decreases were found from pre-to-post during the loading phase in the control group. Rectus femoris activity was higher post intervention during the loading and push-off phases in both groups with larger effect sizes in genu varus. Interpretation: Our findings indicate that the observed changes in ground reaction forces are more prominent in genu varus individuals. Together with our findings on shoe stiffness, it seems appropriate to change running shoes after an intense wearing time of 6 months, particularly in genu varus individuals. KW - footwear KW - electromyography KW - loading rate KW - patients Y1 - 2020 U6 - https://doi.org/10.1016/j.clinbiomech.2020.01.006 SN - 0268-0033 SN - 1879-1271 VL - 73 SP - 55 EP - 62 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Chaabene, Helmi A1 - Prieske, Olaf A1 - Moran, Jason A1 - Negra, Yassine A1 - Attia, Ahmed A1 - Granacher, Urs T1 - Effects of resistance training on Change-of-Direction speed in youth and young physically active and athletic adults: a systematic review with meta-analysis JF - Sports medicine : the world's premier sports medicine preview journal N2 - Background Change-of-direction (CoD) speed is a physical fitness attribute in many field-based team and individual sports. To date, no systematic review with meta-analysis available has examined the effects of resistance training (RT) on CoD speed in youth and adults. Objective To aggregate the effects of RT on CoD speed in youth and young physically active and athletic adults, and to identify the key RT programme variables for training prescription. Data sources A systematic literature search was conducted with PubMed, Web of Science, and Google Scholar, with no date restrictions, up to October 2019, to identify studies related to the effects of RT on CoD speed. Study Eligibility Criteria Only controlled studies with baseline and follow-up measures were included if they examined the effects of RT (i.e., muscle actions against external resistances) on CoD speed in healthy youth (8-18 years) and young physically active/athletic male or female adults (19-28 years). Study Appraisal and Synthesis Methods A random-effects model was used to calculate weighted standardised mean differences (SMD) between intervention and control groups. In addition, an independent single training factor analysis (i.e., RT frequency, intensity, volume) was undertaken. Further, to verify if any RT variable moderated effects on CoD speed, a multivariate random-effects meta-regression was conducted. The methodological quality of the included studies was assessed using the physiotherapy evidence database (PEDro) scale. Results Fifteen studies, comprising 19 experimental groups, were included. The methodological quality of the studies was acceptable with a median PEDro score of 6. There was a significant large effect size of RT on CoD speed across all studies (SMD = - 0.82 [- 1.14 to - 0.49]). Subgroup analyses showed large effect sizes on CoD speed in males (SMD = - 0.95) contrasting with moderate improvements in females (SMD = - 0.60). There were large effect sizes on CoD speed in children (SMD = - 1.28) and adolescents (SMD = - 1.21) contrasting with moderate effects in adults (SMD = - 0.63). There was a moderate effect in elite athletes (SMD = - 0.69) contrasting with a large effect in subelite athletes (SMD = - 0.86). Differences between subgroups were not statistically significant. Similar improvements were observed regarding the effects of independently computed training variables. In terms of RT frequency, our results indicated that two sessions per week induced large effects on CoD speed (SMD = - 1.07) while programmes with three sessions resulted in moderate effects (SMD = - 0.53). For total training intervention duration, we observed large effects for <= 8 weeks (SMD = - 0.81) and > 8 weeks (SMD = - 0.85). For single session duration, we found large effects for <= 30 min and >= 45 min (both SMD = - 1.00). In terms of number of training sessions, we identified large effects for <= 16 sessions (SMD = - 0.83) and > 16 sessions (SMD = - 0.81). For training intensity, we found moderate effects for light-to-moderate (SMD = - 0.76) and vigorous-to-near maximal intensities (SMD = - 0.77). With regards to RT type, we observed large effects for free weights (SMD = - 0.99) and machine-based training (SMD = - 0.80). For combined free weights and machine-based training, moderate effects were identified (SMD = - 0.77). The meta-regression outcomes showed that none of the included training variables significantly predicted the effects of RT on CoD speed (R-2 = 0.00). Conclusions RT seems to be an effective means to improve CoD speed in youth and young physically active and athletic adults. Our findings indicate that the impact of RT on CoD speed may be more prominent in males than in females and in youth than in adults. Additionally, independently computed single factor analyses for different training variables showed that higher compared with lower RT intensities, frequencies, and volumes appear not to have an advantage on the magnitude of CoD speed improvements. In terms of RT type, similar improvements were observed following machine-based and free weights training. Y1 - 2020 U6 - https://doi.org/10.1007/s40279-020-01293-w SN - 0112-1642 SN - 1179-2035 VL - 50 IS - 8 SP - 1483 EP - 1499 PB - Springer CY - Berlin [u.a.] ER - TY - JOUR A1 - Prieske, Olaf A1 - Behrens, Martin A1 - Chaabene, Helmi A1 - Granacher, Urs A1 - Maffiuletti, Nicola A. T1 - Time to differentiate postactivation "potentiation" from "performance enhancement" in the strength and conditioning community JF - Sports medicine : the world's premier sports medicine preview journal N2 - Coaches and athletes in elite sports are constantly seeking to use innovative and advanced training strategies to efficiently improve strength/power performance in already highly-trained individuals. In this regard, high-intensity conditioning contractions have become a popular means to induce acute improvements primarily in muscle contractile properties, which are supposed to translate to subsequent power performances. This performance-enhancing physiological mechanism has previously been called postactivation potentiation (PAP). However, in contrast to the traditional mechanistic understanding of PAP that is based on electrically-evoked twitch properties, an increasing number of studies used the term PAP while referring to acute performance enhancements, even if physiological measures of PAP were not directly assessed. In this current opinion article, we compare the two main approaches (i.e., mechanistic vs. performance) used in the literature to describe PAP effects. We additionally discuss potential misconceptions in the general use of the term PAP. Studies showed that mechanistic and performance-related PAP approaches have different characteristics in terms of the applied research field (basic vs. applied), effective conditioning contractions (e.g., stimulated vs. voluntary), verification (lab-based vs. field tests), effects (twitch peak force vs. maximal voluntary strength), occurrence (consistent vs. inconsistent), and time course (largest effect immediately after vs. similar to 7 min after the conditioning contraction). Moreover, cross-sectional studies revealed inconsistent and trivial-to-large-sized associations between selected measures of mechanistic (e.g., twitch peak force) vs. performance-related PAP approaches (e.g., jump height). In an attempt to avoid misconceptions related to the two different PAP approaches, we propose to use two different terms. Postactivation potentiation should only be used to indicate the increase in muscular force/torque production during an electrically-evoked twitch. In contrast, postactivation performance enhancement (PAPE) should be used to refer to the enhancement of measures of maximal strength, power, and speed following conditioning contractions. The implementation of this terminology would help to better differentiate between mechanistic and performance-related PAP approaches. This is important from a physiological point of view, but also when it comes to aggregating findings from PAP studies, e.g., in the form of meta-analyses, and translating these findings to the field of strength and conditioning. Y1 - 2020 U6 - https://doi.org/10.1007/s40279-020-01300-0 SN - 0112-1642 SN - 1179-2035 VL - 50 IS - 9 SP - 1559 EP - 1565 PB - Springer CY - Berlin [u.a.] ER - TY - JOUR A1 - Fühner, Thea Heidi A1 - Kliegl, Reinhold A1 - Arntz, Fabian A1 - Kriemler, Susi A1 - Granacher, Urs T1 - An update on secular trends in physical fitness of children and adolescents from 1972 to 2015 BT - a systematic review JF - Sports medicine N2 - Background There is evidence that physical fitness of children and adolescents (particularly cardiorespiratory endurance) has declined globally over the past decades. Ever since the first reports on negative trends in physical fitness, efforts have been undertaken by for instance the World Health Organization (WHO) to promote physical activity and fitness in children and adolescents. Therefore, it is timely to re-analyze the literature to examine whether previous reports on secular declines in physical fitness are still detectable or whether they need to be updated. Objectives The objective of this systematic review is to provide an 'update' on secular trends in selected components of physical fitness (i.e., cardiorespiratory endurance, relative muscle strength, proxies of muscle power, speed) in children and adolescents aged 6-18 years. Data Sources A systematic computerized literature search was conducted in the electronic databases PubMed and Web of Science to locate studies that explicitly reported secular trends in physical fitness of children and adolescents. Study Eligibility Criteria Studies were included in this systematic review if they examined secular trends between at least two time points across a minimum of 5 years. In addition, they had to document secular trends in any measure of cardiorespiratory endurance, relative muscle strength, proxies of muscle power or speed in apparently healthy children and adolescents aged 6-18 years. Study Appraisal and Synthesis Methods The included studies were coded for the following criteria: nation, physical fitness component (cardiorespiratory endurance, relative muscle strength, proxies of muscle power, speed), chronological age, sex (boys vs. girls), and year of assessment. Scores were standardized (i.e., converted to z scores) with sample-weighted means and standard deviations, pooled across sex and year of assessment within cells defined by study, test, and children's age. Results The original search identified 524 hits. In the end, 22 studies met the inclusion criteria for review. The observation period was between 1972 and 2015. Fifteen of the 22 studies used tests for cardiorespiratory endurance, eight for relative muscle strength, eleven for proxies of muscle power, and eight for speed. Measures of cardiorespiratory endurance exhibited a large initial increase and an equally large subsequent decrease, but the decrease appears to have reached a floor for all children between 2010 and 2015. Measures of relative muscle strength showed a general trend towards a small increase. Measures of proxies of muscle power indicated an overall small negative quadratic trend. For measures of speed, a small-to-medium increase was observed in recent years. Limitations Biological maturity was not considered in the analysis because biological maturity was not reported in most included studies. Conclusions Negative secular trends were particularly found for cardiorespiratory endurance between 1986 and 2010-12, irrespective of sex. Relative muscle strength and speed showed small increases while proxies of muscle power declined. Although the negative trend in cardiorespiratory endurance appears to have reached a floor in recent years, because of its association with markers of health, we recommend further initiatives in PA and fitness promotion for children and adolescents. More specifically, public health efforts should focus on exercise that increases cardiorespiratory endurance to prevent adverse health effects (i.e.
, overweight and obesity) and muscle strength to lay a foundation for motor skill learning. Y1 - 2020 U6 - https://doi.org/10.1007/s40279-020-01373-x SN - 0112-1642 SN - 1179-2035 VL - 51 IS - 2 SP - 303 EP - 320 PB - Springer CY - Northcote ER -