TY - JOUR A1 - Zouita, Sghaier A1 - Zouhal, Hassane A1 - Ferchichi, Habiba A1 - Paillard, Thierry A1 - Dziri, Catherine A1 - Hackney, Anthony C. A1 - Laher, Ismail A1 - Granacher, Urs A1 - Ben Moussa Zouita, Amira T1 - Effects of Combined Balance and Strength Training on Measures of Balance and Muscle Strength in Older Women With a History of Falls JF - Frontiers in Physiology N2 - Objective: We investigated the effects of combined balance and strength training on measures of balance and muscle strength in older women with a history of falls. Methods: Twenty-seven older women aged 70.4 ± 4.1 years (age range: 65 to 75 years) were randomly allocated to either an intervention (IG, n = 12) or an active control (CG, n = 15) group. The IG completed 8 weeks combined balance and strength training program with three sessions per week including visual biofeedback using force plates. The CG received physical therapy and gait training at a rehabilitation center. Training volumes were similar between the groups. Pre and post training, tests were applied for the assessment of muscle strength (weight-bearing squat [WBS] by measuring the percentage of body mass borne by each leg at different knee flexions [0°, 30°, 60°, and 90°], sit-to-stand test [STS]), and balance. Balance tests used the modified clinical test of sensory interaction (mCTSIB) with eyes closed (EC) and opened (EO), on stable (firm) and unstable (foam) surfaces as well as spatial parameters of gait such as step width and length (cm) and walking speed (cm/s). Results: Significant group × time interactions were found for different degrees of knee flexion during WBS (0.0001 < p < 0.013, 0.441 < d < 0.762). Post hoc tests revealed significant pre-to-post improvements for both legs and for all degrees of flexion (0.0001 < p < 0.002, 0.697 < d < 1.875) for IG compared to CG. Significant group × time interactions were found for firm EO, foam EO, firm EC, and foam EC (0.006 < p < 0.029; 0.302 < d < 0.518). Post hoc tests showed significant pre-to-post improvements for both legs and for all degrees of oscillations (0.0001 < p < 0.004, 0.753 < d < 2.097) for IG compared to CG. This study indicates that combined balance and strength training improved percentage distribution of body weight between legs at different conditions of knee flexion (0°, 30°, 60°, and 90°) and also decreased the sway oscillation on a firm surface with eyes closed, and on foam surface (with eyes opened or closed) in the IG. Conclusion: The higher positive effects of training seen in standing balance tests, compared with dynamic tests, suggests that balance training exercises including lateral, forward, and backward exercises improved static balance to a greater extent in older women. KW - aging KW - exercise KW - postural sway KW - force KW - tasks Y1 - 2020 U6 - https://doi.org/10.3389/fphys.2020.619016 SN - 1664-042X VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Zhou, Lin A1 - Fischer, Eric A1 - Tunca, Can A1 - Brahms, Clemens Markus A1 - Ersoy, Cem A1 - Granacher, Urs A1 - Arnrich, Bert T1 - How We Found Our IMU BT - Guidelines to IMU Selection and a Comparison of Seven IMUs for Pervasive Healthcare Applications JF - Sensors N2 - Inertial measurement units (IMUs) are commonly used for localization or movement tracking in pervasive healthcare-related studies, and gait analysis is one of the most often studied topics using IMUs. The increasing variety of commercially available IMU devices offers convenience by combining the sensor modalities and simplifies the data collection procedures. However, selecting the most suitable IMU device for a certain use case is increasingly challenging. In this study, guidelines for IMU selection are proposed. In particular, seven IMUs were compared in terms of their specifications, data collection procedures, and raw data quality. Data collected from the IMUs were then analyzed by a gait analysis algorithm. The difference in accuracy of the calculated gait parameters between the IMUs could be used to retrace the issues in raw data, such as acceleration range or sensor calibration. Based on our algorithm, we were able to identify the best-suited IMUs for our needs. This study provides an overview of how to select the IMUs based on the area of study with concrete examples, and gives insights into the features of seven commercial IMUs using real data. KW - inertial measurement unit KW - pervasive healthcare KW - gait analysis KW - comparison of devices Y1 - 2020 U6 - https://doi.org/10.3390/s20154090 SN - 1424-8220 VL - 20 IS - 15 PB - MDPI CY - Basel ER - TY - JOUR A1 - Thiele, Dirk A1 - Prieske, Olaf A1 - Lesinski, Melanie A1 - Granacher, Urs T1 - Effects of Equal Volume Heavy-Resistance Strength Training Versus Strength Endurance Training on Physical Fitness and Sport-Specific Performance in Young Elite Female Rowers JF - Frontiers in Physiology N2 - Strength training is an important means for performance development in young rowers. The purpose of this study was to examine the effects of a 9-week equal volume heavy-resistance strength training (HRST) versus strength endurance training (SET) in addition to regular rowing training on primary (e.g., maximal strength/power) and secondary outcomes (e.g., balance) in young rowers. Twenty-six female elite adolescent rowers were assigned to an HRST (n = 12; age: 13.2 ± 0.5 yrs; maturity-offset: +2.0 ± 0.5 yrs) or a SET group (n = 14; age: 13.1 ± 0.5 yrs; maturity-offset: +2.1 ± 0.5 yrs). HRST and SET comprised lower- (i.e., leg press/knee flexion/extension), upper-limbs (i.e., bench press/pull; lat-pull down), and complex exercises (i.e., rowing ergometer). HRST performed four sets with 12 repetitions per set at an intensity of 75–95% of the one-repetition maximum (1-RM). SET conducted four sets with 30 repetitions per set at 50–60% of the 1-RM. Training volume was matched for overall repetitions × intensity × training per week. Pre-post training, tests were performed for the assessment of primary [i.e., maximal strength (e.g., bench pull/knee flexion/extension 1-RM/isometric handgrip test), muscle power (e.g., medicine-ball push test, triple hop, drop jump, and countermovement jump), anaerobic endurance (400-m run), sport-specific performance (700-m rowing ergometer trial)] and secondary outcomes [dynamic balance (Y-balance test), change-of-direction (CoD) speed (multistage shuttle-run test)]. Adherence rate was >87% and one athlete of each group dropped out. Overall, 24 athletes completed the study and no test or training-related injuries occurred. Significant group × time interactions were observed for maximal strength, muscle power, anaerobic endurance, CoD speed, and sport-specific performance (p ≤ 0.05; 0.45 ≤ d ≤ 1.11). Post hoc analyses indicated larger gains in maximal strength and muscle power following HRST (p ≤ 0.05; 1.81 ≤ d ≤ 3.58) compared with SET (p ≤ 0.05; 1.04 ≤ d ≤ 2.30). Furthermore, SET (p ≤ 0.01; d = 2.08) resulted in larger gains in sport-specific performance compared with HRST (p < 0.05; d = 1.3). Only HRST produced significant pre-post improvements for anaerobic endurance and CoD speed (p ≤ 0.05; 1.84 ≤ d ≤ 4.76). In conclusion, HRST in addition to regular rowing training was more effective than SET to improve selected measures of physical fitness (i.e., maximal strength, muscle power, anaerobic endurance, and CoD speed) and SET was more effective than HRST to enhance sport-specific performance gains in female elite young rowers. KW - concurrent training KW - plyometric training KW - on-water performance KW - race time KW - oarsmen Y1 - 2020 U6 - https://doi.org/10.3389/fphys.2020.00888 SN - 1664-042X VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Thiele, Dirk A1 - Prieske, Olaf A1 - Chaabene, Helmi A1 - Granacher, Urs T1 - Effects of strength training on physical fitness and sport-specific performance in recreational, sub-elite, and elite rowers BT - a systematic review with meta-analysis JF - Journal of sports sciences N2 - The purpose of this systematic review with meta-analysis was to examine the effects of strength training (ST) on selected components of physical fitness (e.g., lower/upper limb maximal strength, muscular endurance, jump performance, cardiorespiratory endurance) and sport-specific performance in rowers. Only studies with an active control group were included if they examined the effects of ST on at least one proxy of physical fitness and/or sport-specific performance in rowers. Weighted and averaged standardized mean differences (SMD) were calculated using random-effects models. Subgroup analyses were computed to identify effects of ST type or expertise level on sport-specific performance. Our analyses revealed significant small effects of ST on lower limb maximal strength (SMD = 0.42, p = 0.05) and on sport-specific performance (SMD = 0.32, p = 0.05). Non-significant effects were found for upper limb maximal strength, upper/lower limb muscular endurance, jump performance, and cardiorespiratory endurance. Subgroup analyses for ST type and expertise level showed non-significant differences between the respective subgroups of rowers (p >= 0.32). Our systematic review with meta-analysis indicated that ST is an effective means for improving lower limb maximal strength and sport-specific performance in rowers. However, ST-induced effects are neither modulated by ST type nor rowers' expertise level. KW - resistance training KW - plyometric training KW - on-water performance KW - race KW - time KW - oarsmen KW - athletic performance Y1 - 2020 U6 - https://doi.org/10.1080/02640414.2020.1745502 SN - 0264-0414 SN - 1466-447X VL - 38 IS - 10 SP - 1186 EP - 1195 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Sandau, Ingo A1 - Granacher, Urs T1 - Effects of the barbell load on the acceleration phase during the snatch in elite Olympic weightlifting JF - Sports N2 - The load-depended loss of vertical barbell velocity at the end of the acceleration phase limits the maximum weight that can be lifted. Thus, the purpose of this study was to analyze how increased barbell loads affect the vertical barbell velocity in the sub-phases of the acceleration phase during the snatch. It was hypothesized that the load-dependent velocity loss at the end of the acceleration phase is primarily associated with a velocity loss during the 1st pull. For this purpose, 14 male elite weightlifters lifted seven load-stages from 70-100% of their personal best in the snatch. The load-velocity relationship was calculated using linear regression analysis to determine the velocity loss at 1st pull, transition, and 2nd pull. A group mean data contrast analysis revealed the highest load-dependent velocity loss for the 1st pull (t = 1.85, p = 0.044, g = 0.49 [-0.05, 1.04]) which confirmed our study hypothesis. In contrast to the group mean data, the individual athlete showed a unique response to increased loads during the acceleration sub-phases of the snatch. With the proposed method, individualized training recommendations on exercise selection and loading schemes can be derived to specifically improve the sub-phases of the snatch acceleration phase. Furthermore, the results highlight the importance of single-subject assessment when working with elite athletes in Olympic weightlifting. KW - biomechanics KW - barbell velocity KW - performance KW - training KW - load-velocity KW - relationship Y1 - 2020 U6 - https://doi.org/10.3390/sports8050059 SN - 2075-4663 VL - 8 IS - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Saidi, Karim A1 - Ben Abderrahman, Abderraouf A1 - Boullosa, Daniel A1 - Dupont, Grégory A1 - Hackney, Anthony C. A1 - Bideau, Benoit A1 - Pavillon, Thomas A1 - Granacher, Urs A1 - Zouhal, Hassane T1 - The Interplay Between Plasma Hormonal Concentrations, Physical Fitness, Workload and Mood State Changes to Periods of Congested Match Play in Professional Soccer Players JF - Frontiers in Physiology N2 - Background: The regular assessment of hormonal and mood state parameters in professional soccer are proposed as good indicators during periods of intense training and/or competition to avoid overtraining. Objective: The aim of this study was to analyze hormonal, psychological, workload and physical fitness parameters in elite soccer players in relation to changes in training and match exposure during a congested period of match play. Methods: Sixteen elite soccer players from a team playing in the first Tunisian soccer league were evaluated three times (T1, T2, and T3) over 12 weeks. The non-congested period of match play was from T1 to T2, when the players played 6 games over 6 weeks. The congested period was from T2 to T3, when the players played 10 games over 6 weeks. From T1 to T3, players performed the Yo-Yo intermittent recovery test level 1 (YYIR1), the repeated shuttle sprint ability test (RSSA), the countermovement jump test (CMJ), and the squat jump test (SJ). Plasma Cortisol (C), Testosterone (T), and the T/C ratio were analyzed at T1, T2, and T3. Players had their mood dimensions (tension, depression, anger, vigor, fatigue, confusion, and a Total Mood Disturbance) assessed through the Profile of Mood State questionnaire (POMS). Training session rating of perceived exertion (sRPE) was also recorded on a daily basis in order to quantify internal training load and elements of monotony and strain. Results: Significant performance declines (T1 < T2 < T3) were found for SJ performance (p = 0.04, effect size [ES] ES₁₋₂ = 0.15−0.06, ES₂₋₃ = 0.24) from T1 to T3. YYIR1 performance improved significantly from T1 to T2 and declined significantly from T2 to T3 (p = 0.001, ES₁₋₂ = 0.24, ES₂₋₃ = −2.54). Mean RSSA performance was significantly higher (p = 0.019, ES₁₋₂ = −0.47, ES₂₋₃ = 1.15) in T3 compared with T2 and T1. Best RSSA performance was significantly higher in T3 when compared with T2 and T1 (p = 0.006, ES₂₋₃ = 0.47, ES₁₋₂ = −0.56), but significantly lower in T2 when compared with to T1. T and T/C were significantly lower in T3 when compared with T2 and T1 (T: p = 0.03, ES₃₋₂ = −0.51, ES₃₋₁ = −0.51, T/C: p = 0.017, ES₃₋₂ = −1.1, ES₃₋₁ = −1.07). Significant decreases were found for the vigor scores in T3 when compared to T2 and T1 (p = 0.002, ES₁₋₂ = 0.31, ES₃₋₂ = −1.25). A significant increase was found in fatigue scores in T3 as compared to T1 and T2 (p = 0.002, ES₁₋₂ = 0.43, ES₂₋₃ = 0.81). A significant increase was found from T1 < T2 < T3 intension score (p = 0.002, ES₁₋₂ = 1.1, ES₂₋₃ = 0.2) and anger score (p = 0.03, ES₁₋₂ = 0.47, ES₂₋₃ = 0.33) over the study period. Total mood disturbance increased significantly (p = 0.02, ES₁₋₂ = 0.91, ES₂₋₃ = 1.1) from T1 to T3. Between T1-T2, significant relationships were observed between workload and changes in T (r = 0.66, p = 0.003), and T/C ratio (r = 0.62, p = 0.01). There were significant relationships between performance in RSSAbest and training load parameters (workload: r = 0.52, p = 0.03; monotony: r = 0.62, p = 0.01; strain: r = 0.62, p = 0.009). Between T2-T3, there was a significant relationship between Δ% of total mood disturbance and Δ% of YYIR1 (r = −0.54; p = 0.04), RSSAbest (r = 0.58, p = 0.01), SJ (r = −0,55, p = 0.01), T (r = 0.53; p = 0.03), and T/C (r = 0.5; p = 0.04). Conclusion: An intensive period of congested match play significantly compromised elite soccer players’ physical and mental fitness. These changes were related to psychological but not hormonal parameters; even though significant alterations were detected for selected measures. Mood monitoring could be a simple and useful tool to determine the degree of preparedness for match play during a congested period in professional soccer. KW - training KW - hormones KW - overtraining KW - overreaching KW - recovery Y1 - 2020 U6 - https://doi.org/10.3389/fphys.2020.00835 SN - 1664-042X VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Ravé, Guillaume A1 - Granacher, Urs A1 - Boullosa, Daniel A1 - Hackney, Anthony C. A1 - Zouhal, Hassane T1 - How to Use Global Positioning Systems (GPS) Data to Monitor Training Load in the “Real World” of Elite Soccer JF - Frontiers in Physiology KW - acute chronic workload ratio KW - injury risk KW - physical performance KW - monitoring KW - external training load Y1 - 2020 U6 - https://doi.org/10.3389/fphys.2020.00944 SN - 1664-042X VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Prieske, Olaf A1 - Chaabene, Helmi A1 - Gäbler, Martijn A1 - Herz, Michael A1 - Helm, Norman A1 - Markov, Adrian A1 - Granacher, Urs T1 - Seasonal changes in anthropometry, body composition, and physical fitness and the relationships with sporting success in young sub-elite judo athletes BT - an exploratory study JF - International journal of environmental research and public health : IJERPH N2 - This exploratory study aimed to monitor long-term seasonal developments in measures of anthropometry, body composition, and physical fitness in young judo athletes, and to compute associations between these measures and sporting success. Forty-four young judoka (20 females, 24 males) volunteered to participate. Tests for the assessment of anthropometry (e.g., body height/mass), body-composition (e.g., lean body mass), muscle strength (isometric handgrip strength), vertical jumping (e.g., countermovement-jump (CMJ) height), and dynamic balance (Y-balance test) were conducted at the beginning and end of a 10-month training season. Additionally, sporting success at the end of the season was recorded for each athlete. Analyses revealed significant time x sex interaction effects for lean-body-mass, isometric handgrip strength, and CMJ height (0.7 <= d <= 1.6). Post-hoc analyses showed larger gains for all measures in young males (1.9 <= d <= 6.0) compared with females (d = 2.4) across the season. Additionally, significant increases in body height and mass as well as Y-balance test scores were found from pre-to-post-test (1.2 <= d <= 4.3), irrespective of sex. Further, non-significant small-to-moderate-sized correlations were identified between changes in anthropometry/body composition/physical fitness and sporting success (p > 0.05; -0.34 <= rho <= 0.32). Regression analysis confirmed that no model significantly predicted sporting success. Ten months of judo training and/or growth/maturation contributed to significant changes in anthropometry, body composition, and physical fitness, particularly in young male judo athletes. KW - combat sports KW - periodization KW - somatic variables KW - training load KW - training KW - monitoring KW - young athletes Y1 - 2020 U6 - https://doi.org/10.3390/ijerph17197169 SN - 1660-4601 VL - 17 IS - 19 PB - MDPI AG CY - Basel 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 - 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 - Negra, Yassine A1 - Chaabene, Helmi A1 - Sammoud, Senda A1 - Prieske, Olaf A1 - Moran, Jason A1 - Ramirez-Campillo, Rodrigo A1 - Nejmaoui, Ali A1 - Granacher, Urs T1 - The increased effectiveness of loaded versus unloaded plyometric jump training in improving muscle power, speed, change of direction, and kicking-distance performance in prepubertal male soccer players JF - International journal of sports physiology and performance : IJSSP N2 - Purpose: To examine the effects of loaded (LPJT) versus unloaded plyometric jump training (UPJT) programs on measures of muscle power, speed, change of direction (CoD), and kicking-distance performance in prepubertal male soccer players. Methods: Participants (N = 29) were randomly assigned to a LPJT group (n = 13; age = 13.0 [0.7] y) using weighted vests or UPJT group (n = 16; age = 13.0 [0.5] y) using body mass only. Before and after the intervention, tests for the assessment of proxies of muscle power (ie, countermovement jump, standing long jump); speed (ie, 5-, 10-, and 20-m sprint); CoD (ie, Illinois CoD test, modified 505 agility test); and kicking-distance were conducted. Data were analyzed using magnitude-based inferences. Results: Within-group analyses for the LPJT group showed large and very large improvements for 10-m sprint time (effect size [ES] = 2.00) and modified 505 CoD (ES = 2.83) tests, respectively. For the same group, moderate improvements were observed for the Illinois CoD test (ES = 0.61), 5- and 20-m sprint time test (ES = 1.00 for both the tests), countermovement jump test (ES = 1.00), and the maximal kicking-distance test (ES = 0.90). Small enhancements in the standing long jump test (ES = 0.50) were apparent. Regarding the UPJT group, small improvements were observed for all tests (ES = 0.33-0.57), except 5- and 10-m sprint time (ES = 1.00 and 0.63, respectively). Between-group analyses favored the LPJT group for the modified 505 CoD (ES = 0.61), standing long jump (ES = 0.50), and maximal kicking-distance tests (ES = 0.57), but not for the 5-m sprint time test (ES = 1.00). Only trivial between-group differences were shown for the remaining tests (ES = 0.00-0.09). Conclusion: Overall, LPJT appears to be more effective than UPJT in improving measures of muscle power, speed, CoD, and kicking-distance performance in prepubertal male soccer players. KW - young KW - football KW - stretch-shortening cycle KW - maturity KW - athletic KW - performance Y1 - 2020 U6 - https://doi.org/10.1123/ijspp.2018-0866 SN - 1555-0265 SN - 1555-0273 VL - 15 IS - 2 SP - 189 EP - 195 PB - Human Kinetics CY - Champaign, Ill. ER - TY - JOUR A1 - Negra, Yassine A1 - Chaabene, Helmi A1 - Fernandez-Fernandez, Jaime A1 - Sammoud, Senda A1 - Bouguezzi, Raja A1 - Prieske, Olaf A1 - Granacher, Urs T1 - Short-term plyometric Jump training improves repeated-sprint ability in prepuberal male soccer players JF - Journal of strength and conditioning research : the research journal of the NSCA N2 - This study examined the effects of a short-term (i.e., 8 weeks) combined horizontal and vertical plyometric jump training (PJT) program in combination with regular soccer-specific training as compared with soccer-specific training only on jump and change of direction (CoD) performances, speed, and repeated-sprint ability (RSA) in prepuberal male soccer players. Twenty-four players were recruited and randomly assigned to either a PJT group (PJT(G); n = 13; 12.7 +/- 0.2 years) or an active control group (CONG; n = 11; 12.7 +/- 0.2 years). The outcome measures included tests for the assessment of jump performance (drop jump from 20- to 40-cm height [DJ20 and DJ40] and 3-hop test [THT]), speed (20-m sprint), CoD (T-test), and RSA (20-m repeated shuttle sprint). Data were analyzed using magnitude-based inferences. Within-group analyses revealed large performance improvements in the T-test (d = -1.2), DJ20 (d = 3.7), DJ40 (d = 3.6), THT (d = 0.6), and the RSA(total) (d = -1.6) in the PJT(G). Between-group analyses showed greater performance improvements in the T-test (d = -2.9), 20-m sprint time (d = -2.0), DJ20 (d = 2.4), DJ40 (d = 2.0), THT (d = 1.9), RSA(best) (d = -1.9), and the RSA(total) (d = -1.9) in the PJT(G) compared with CONG. Eight weeks of an in-season PJT in addition to regular soccer-specific training induced larger increases in measures of physical fitness in prepuberal male soccer players compared with regular soccer-specific training only. More specifically, PJT was effective in improving RSA performance. KW - youth KW - stretch-shortening cycle KW - athletic performance KW - soccer Y1 - 2020 U6 - https://doi.org/10.1519/JSC.0000000000002703 SN - 1064-8011 SN - 1533-4287 VL - 34 IS - 11 SP - 3241 EP - 3249 PB - Lippincott Williams & Wilkins CY - Philadelphia 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 - 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 - Lesinski, Melanie A1 - Herz, Michael A1 - Schmelcher, Alina A1 - Granacher, Urs T1 - Effects of resistance training on physical fitness in healthy children and adolescents BT - an umbrella review JF - Sports medicine N2 - Background Over the past decades, an exponential growth has occurred with regards to the number of scientific publications including meta-analyses on youth resistance training (RT). Accordingly, it is timely to summarize findings from meta-analyses in the form of an umbrella review. Objectives To systematically review and summarise the findings of published meta-analyses that investigated the effects of RT on physical fitness in children and adolescents. Design Systematic umbrella review of meta-analyses. Data Sources Meta-analyses were identified using systematic literature searches in the databases PubMed, Web of Science, and Cochrane Library. Eligibility Criteria for Selecting Meta-analyses Meta-analyses that examined the effects of RT on physical fitness (e.g., muscle strength, muscle power) in healthy youth (<= 18 years). Results Fourteen meta-analyses were included in this umbrella review. Eleven of these meta-analyses reported between-subject effect sizes which are important to eliminate bias due to growth and maturation. RT produced medium-to-large effects on muscle strength, small-to-large effects on muscle power, small-to-medium effects on linear sprint, a medium effect on agility/change-of-direction speed, small-to-large effects on throwing performance, and a medium effect on sport-specific enhancement. There were few consistent moderating effects of maturation, age, sex, expertise level, or RT type on muscle strength and muscle power across the included meta-analyses. The analysed meta-analyses showed low-to-moderate methodological quality (AMSTAR2) as well as presented evidence of low-to-very low quality (GRADE). Conclusion This umbrella review proved the effectiveness of RT in youth on a high evidence level. The magnitude of effects varies according to the respective outcome measure and it appears to follow the principle of training specificity. Larger effect sizes were found for strength-related outcome measures. Future studies should consistently report data on participants' maturational status. More research is needed with prepubertal children and girls, irrespective of their maturational status. Y1 - 2020 U6 - https://doi.org/10.1007/s40279-020-01327-3 SN - 0112-1642 SN - 1179-2035 VL - 50 IS - 11 SP - 1901 EP - 1928 PB - Springer CY - Northcote 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 - 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 - Helm, Norman A1 - Prieske, Olaf A1 - Mühlbauer, Thomas A1 - Krüger, Tom A1 - Retzlaff, Matthias A1 - Granacher, Urs T1 - Associations between trunk muscle strength and judo-specific pulling performances in judo athletes T1 - Assoziationen zwischen der Rumpfkraft und judospezifischen Anriss-Leistungen von Judoka JF - Sportverletzung, Sportschaden : Grundlagen, Prävention, Rehabilitation N2 - Background: Good trunk stability is an important prerequisite for the mobility of the upper and lower limbs during sport-specific movements. Therefore, trunk muscle strength may represent an important performance determinant for judo-specific movements. This study aimed at evaluating statistical correlations between trunk muscle strength and kinetic parameters during judo-specific pulling movements in judo players. Method: Twenty-one male sub-elite judo players aged 22 +/- 4 years with a mean training volume of 15 +/- 4 hours per week participated in this study. Peak isokinetic torque (PIT) of the trunk flexors (PITFlex), extensors (PITEx) and rotators (PITRot) was tested using an isokinetic dynamometer (IsoMed 2000). In addition, two kinetic parameters (mechanical work [W], maximal force [F-max]) were analysed using the judo-specific measurement and information system JERGo (c). For this purpose, athletes were asked to do their judo-specific pulling movements while standing and with a dynamic change of position (i.e. Morote-seoi-nage). Results: Regarding pulling movements while standing, significant correlations (0.62 <= r(P) <= 0.72) were found between isokinetic tests (PITFlex, PITEx, PITRot) and mechanical work during judo-specific movement. Further, significant correlations (0.59 <= r(P) <= 0.65) were detected between isokinetic tests (PITEx, PITRot) and judo-specific pulling movements (Fmax). Regarding pulling movements with a change of position, significant correlations (0.47 <= r(P) <= 0.88) were observed between isokinetics (PITFlex, PITEx, PITRot) and the kinetic pulling parameters (W, Fmax), irrespective of the examined arm. No significant differences in magnitude of correlation coefficients were found between PIT of the trunk flexors, extensors, and rotators and judo-specific movements. Further, the regression analysis indicated that PIT of the trunk extensors is the single best predictor for mechanical work during pulling movements while standing (46.9 %). Trunk rotator PIT is the single best predictor for mechanical work during pulling movements with a change of position (69.4 %). Conclusions: Findings from this study indicate that trunk muscle strength, particularly trunk rotator PIT is associated with kinetic pulling variables during pulling movements with a change of position. This implies that the development of trunk rotator strength could have an impact on pulling movements with a change of position (i.e. Morote-seoi-nage) in judo athletes. N2 - Hintergrund: Eine gut ausgeprägte Rumpfstabilität ist eine wichtige Voraussetzung für die Mobilität der oberen und unteren Extremitäten während des sportlichen Bewegungsvollzugs. Vor diesem Hintergrund könnte die Rumpfkraft ein leistungsdeterminierender Faktor bei der Ausführung judospezifischer Bewegungen darstellen. Das Ziel der vorliegenden Studie war es, statistische Zusammenhänge zwischen der Rumpfkraft und kinetischen Parametern bei Anriss-Bewegungen von Judoka zu untersuchen. Methode: An der Untersuchung nahmen 21 leistungsorientierte Judoka mit einem mittleren Alter von 22 ± 4 Jahre und einem Trainingsumfang von 15 ± 4 Stunden pro Woche teil. Das maximale isokinetische Drehmoment (PIT) der Rumpfflexoren (PITFlex), -extensoren (PITEx) und -rotatoren (PITRot) wurde unter Verwendung eines isokinetischen Dynamometers (IsoMed 2000) erfasst. Zusätzlich wurden kinetische Parameter (mechanische Arbeit [W], dynamisch-realisierte Maximalkraft [Fmax]) bei Anriss-Bewegung im Stand und bei Anriss- mit Eindrehbewegung (d. h. Morote-seoi-nage) mithilfe eines judospezifischen Mess- und Informationssystems (JERGo©) erhoben. Ergebnisse: Die statistische Analyse zeigte signifikante Korrelationen (0,62 ≤ r P ≤ 0,72) zwischen den maximalen isokinetischen Drehmomenten (PITFlex, PITEx, PITRot) und der Anriss-Bewegung im Stand (W). Zudem konnten signifikante Zusammenhänge (0,59 ≤ r P ≤ 0,65) zwischen den isokinetischen Tests (PITEx, PITRot) und Fmax auf der Hubarmseite bei der Anriss-Bewegung im Stand gefunden werden. Für die Anriss- mit Eindrehbewegung ergaben sich signifikante Korrelationen (0,47 ≤ r P ≤ 0,88) zwischen den isokinetischen Tests (PITFlex, PITEx, PITRot) und Leistungskennwerten der judospezifischen Bewegung (W und Fmax), unabhängig von der untersuchten Armseite. Es wurden vergleichbare Korrelationskoeffizienten zwischen PIT der Rumpfflexoren, -extensoren und -rotatoren und judospezifischen Leistungskennwerten festgestellt. Weiterhin identifizierte die Regressionsanalyse den Kennwert PIT bei Rumpfextension als besten Prädiktor für die mechanische Arbeit bei Anriss-Bewegung im Stand (46,9 %). Bei der Anriss- mit Eindrehbewegung konnte PIT der Rumpfrotatoren auf die Hubarmseite als bester Prädiktor für die mechanische Arbeit (69,4 %) ermittelt werden. Schlussfolgerung: Die Ergebnisse zeigen, dass die Rumpfkraft, insbesondere bei der Rumpfrotationsbewegung, mit Variablen der judospezifischen Leistungskennwerte bei der Anriss- mit Eindrehbewegung assoziiert ist. Dies impliziert, dass vor allem durch rumpfrotationskräftigende Übungen Einfluss auf die Anriss- mit Eindrehbewegung (d. h. Morote-seoi-nage) genommen werden könnte. KW - combat sport KW - athletic performance KW - Morote-seoi-nage KW - Kampfsport KW - sportliche Leistung Y1 - 2020 U6 - https://doi.org/10.1055/a-0677-9608 SN - 0932-0555 SN - 1439-1236 VL - 34 IS - 1 SP - 18 EP - 27 PB - Thieme CY - Stuttgart 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 - Gebel, Arnd A1 - Lehmann, Tim A1 - Granacher, Urs T1 - Balance task difficulty affects postural sway and cortical activity in healthy adolescents JF - Experimental brain research N2 - Electroencephalographic (EEG) research indicates changes in adults' low frequency bands of frontoparietal brain areas executing different balance tasks with increasing postural demands. However, this issue is unsolved for adolescents when performing the same balance task with increasing difficulty. Therefore, we examined the effects of a progressively increasing balance task difficulty on balance performance and brain activity in adolescents. Thirteen healthy adolescents aged 16-17 year performed tests in bipedal upright stance on a balance board with six progressively increasing levels of task difficulty. Postural sway and cortical activity were recorded simultaneously using a pressure sensitive measuring system and EEG. The power spectrum was analyzed for theta (4-7 Hz) and alpha-2 (10-12 Hz) frequency bands in pre-defined frontal, central, and parietal clusters of electrocortical sources. Repeated measures analysis of variance (rmANOVA) showed a significant main effect of task difficulty for postural sway (p < 0.001; d = 6.36). Concomitantly, the power spectrum changed in frontal, bilateral central, and bilateral parietal clusters. RmANOVAs revealed significant main effects of task difficulty for theta band power in the frontal (p < 0.001, d = 1.80) and both central clusters (left: p < 0.001, d = 1.49; right: p < 0.001, d = 1.42) as well as for alpha-2 band power in both parietal clusters (left: p < 0.001, d = 1.39; right: p < 0.001, d = 1.05) and in the central right cluster (p = 0.005, d = 0.92). Increases in theta band power (frontal, central) and decreases in alpha-2 power (central, parietal) with increasing balance task difficulty may reflect increased attentional processes and/or error monitoring as well as increased sensory information processing due to increasing postural demands. In general, our findings are mostly in agreement with studies conducted in adults. Similar to adult studies, our data with adolescents indicated the involvement of frontoparietal brain areas in the regulation of postural control. In addition, we detected that activity of selected brain areas (e.g., bilateral central) changed with increasing postural demands. KW - balance KW - postural control KW - EEG KW - Theta KW - Alpha-2 KW - ICA KW - youth Y1 - 2020 U6 - https://doi.org/10.1007/s00221-020-05810-1 SN - 0014-4819 SN - 1432-1106 VL - 238 IS - 5 SP - 1323 EP - 1333 PB - Springer CY - New York ER -