TY - JOUR A1 - Albert, Justin Amadeus A1 - Owolabi, Victor A1 - Gebel, Arnd A1 - Brahms, Clemens Markus A1 - Granacher, Urs A1 - Arnrich, Bert T1 - Evaluation of the Pose Tracking Performance of the Azure Kinect and Kinect v2 for Gait Analysis in Comparison with a Gold Standard BT - A Pilot Study JF - Sensors N2 - Gait analysis is an important tool for the early detection of neurological diseases and for the assessment of risk of falling in elderly people. The availability of low-cost camera hardware on the market today and recent advances in Machine Learning enable a wide range of clinical and health-related applications, such as patient monitoring or exercise recognition at home. In this study, we evaluated the motion tracking performance of the latest generation of the Microsoft Kinect camera, Azure Kinect, compared to its predecessor Kinect v2 in terms of treadmill walking using a gold standard Vicon multi-camera motion capturing system and the 39 marker Plug-in Gait model. Five young and healthy subjects walked on a treadmill at three different velocities while data were recorded simultaneously with all three camera systems. An easy-to-administer camera calibration method developed here was used to spatially align the 3D skeleton data from both Kinect cameras and the Vicon system. With this calibration, the spatial agreement of joint positions between the two Kinect cameras and the reference system was evaluated. In addition, we compared the accuracy of certain spatio-temporal gait parameters, i.e., step length, step time, step width, and stride time calculated from the Kinect data, with the gold standard system. Our results showed that the improved hardware and the motion tracking algorithm of the Azure Kinect camera led to a significantly higher accuracy of the spatial gait parameters than the predecessor Kinect v2, while no significant differences were found between the temporal parameters. Furthermore, we explain in detail how this experimental setup could be used to continuously monitor the progress during gait rehabilitation in older people. KW - motion capture KW - evaluation KW - human motion KW - RGB-D cameras KW - digital health Y1 - 2020 U6 - https://doi.org/10.3390/s20185104 SN - 1424-8220 VL - 20 IS - 18 PB - MDPI CY - Basel ER - TY - GEN A1 - Albert, Justin Amadeus A1 - Owolabi, Victor A1 - Gebel, Arnd A1 - Brahms, Clemens Markus A1 - Granacher, Urs A1 - Arnrich, Bert T1 - Evaluation of the Pose Tracking Performance of the Azure Kinect and Kinect v2 for Gait Analysis in Comparison with a Gold Standard BT - A Pilot Study T2 - Postprints der Universität Potsdam : Reihe der Digital Engineering Fakultät N2 - Gait analysis is an important tool for the early detection of neurological diseases and for the assessment of risk of falling in elderly people. The availability of low-cost camera hardware on the market today and recent advances in Machine Learning enable a wide range of clinical and health-related applications, such as patient monitoring or exercise recognition at home. In this study, we evaluated the motion tracking performance of the latest generation of the Microsoft Kinect camera, Azure Kinect, compared to its predecessor Kinect v2 in terms of treadmill walking using a gold standard Vicon multi-camera motion capturing system and the 39 marker Plug-in Gait model. Five young and healthy subjects walked on a treadmill at three different velocities while data were recorded simultaneously with all three camera systems. An easy-to-administer camera calibration method developed here was used to spatially align the 3D skeleton data from both Kinect cameras and the Vicon system. With this calibration, the spatial agreement of joint positions between the two Kinect cameras and the reference system was evaluated. In addition, we compared the accuracy of certain spatio-temporal gait parameters, i.e., step length, step time, step width, and stride time calculated from the Kinect data, with the gold standard system. Our results showed that the improved hardware and the motion tracking algorithm of the Azure Kinect camera led to a significantly higher accuracy of the spatial gait parameters than the predecessor Kinect v2, while no significant differences were found between the temporal parameters. Furthermore, we explain in detail how this experimental setup could be used to continuously monitor the progress during gait rehabilitation in older people. T3 - Zweitveröffentlichungen der Universität Potsdam : Reihe der Digital Engineering Fakultät - 3 KW - motion capture KW - evaluation KW - human motion KW - RGB-D cameras KW - digital health Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-484130 IS - 3 ER - TY - JOUR A1 - Arazi, Hamid A1 - Asadi, Abbas A1 - Khalkhali, Farhood A1 - Boullosa, Daniel A1 - Hackney, Anthony C. A1 - Granacher, Urs A1 - Zouhal, Hassane T1 - Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players BT - A Preliminary Study N2 - This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r²) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season. KW - training load KW - rate of perceived exertion KW - rolling averages KW - weighted moving averages KW - football Y1 - 2020 U6 - https://doi.org/10.3389/fphys.2020.00608 SN - 1664-042X VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Arazi, Hamid A1 - Asadi, Abbas A1 - Khalkhali, Farhood A1 - Boullosa, Daniel A1 - Hackney, Anthony C. A1 - Granacher, Urs A1 - Zouhal, Hassane T1 - Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players BT - A Preliminary Study JF - Frontiers in Physiology N2 - This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r 2) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season. KW - training load KW - rate of perceived exertion KW - rolling averages KW - weighted moving averages KW - football Y1 - 2020 U6 - https://doi.org/10.3389/fphys.2020.00995 SN - 1664-042X VL - 11 PB - Frontiers Research Foundation CY - Lausanne ER - TY - GEN A1 - Arazi, Hamid A1 - Asadi, Abbas A1 - Khalkhali, Farhood A1 - Boullosa, Daniel A1 - Hackney, Anthony C. A1 - Granacher, Urs A1 - Zouhal, Hassane T1 - Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players BT - A Preliminary Study T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe N2 - This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r 2) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 666 KW - training load KW - rate of perceived exertion KW - rolling averages KW - weighted moving averages KW - football Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-482330 SN - 1866-8364 IS - 666 ER - TY - GEN A1 - Arazi, Hamid A1 - Asadi, Abbas A1 - Khalkhali, Farhood A1 - Boullosa, Daniel A1 - Hackney, Anthony C. A1 - Granacher, Urs A1 - Zouhal, Hassane T1 - Association Between the Acute to Chronic Workload Ratio and Injury Occurrence in Young Male Team Soccer Players BT - A Preliminary Study T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe N2 - This study aimed to investigate the relationship between the acute to chronic workload ratio (ACWR), based upon participant session rating of perceived exertion (sRPE), using two models [(1) rolling averages (ACWRRA); and (2) exponentially weighted moving averages (ACWREWMA)] and the injury rate in young male team soccer players aged 17.1 ± 0.7 years during a competitive mesocycle. Twenty-two players were enrolled in this study and performed four training sessions per week with 2 days of recovery and 1 match day per week. During each training session and each weekly match, training time and sRPE were recorded. In addition, training impulse (TRIMP), monotony, and strain were subsequently calculated. The rate of injury was recorded for each soccer player over a period of 4 weeks (i.e., 28 days) using a daily questionnaire. The results showed that over the course of the study, the number of non-contact injuries was significantly higher than that for contact injuries (2.5 vs. 0.5, p = 0.01). There were also significant positive correlations between sRPE and training time (r = 0.411, p = 0.039), ACWRRA (r = 0.47, p = 0.049), and ACWREWMA (r = 0.51, p = 0.038). In addition, small-to-medium correlations were detected between ACWR and non-contact injury occurrence (ACWRRA, r = 0.31, p = 0.05; ACWREWMA, r = 0.53, p = 0.03). Explained variance (r²) for non-contact injury was significantly greater using the ACWREWMA model (ranging between 21 and 52%) compared with ACWRRA (ranging between 17 and 39%). In conclusion, the results of this study showed that the ACWREWMA model is more sensitive than ACWRRA to identify non-contact injury occurrence in male team soccer players during a short period in the competitive season. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 644 KW - training load KW - rate of perceived exertion KW - rolling averages KW - weighted moving averages KW - football Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-472961 SN - 1866-8364 IS - 644 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 - GEN A1 - Chaabene, Helmi A1 - Lesinski, Melanie A1 - Behm, David George A1 - Granacher, Urs T1 - Performance- and healthrelated benefits of youth resistance training T1 - Leistungs- und gesundheitsbezogene Wirkungen von Krafttraining mit Heranwachsenden T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe N2 - There is ample evidence that youth resistance training (RT) is safe, joyful, and effective for different markers of performance (e.g., muscle strength, power, linear sprint speed) and health (e.g., injury prevention). Accordingly, the first aim of this narrative review is to present and discuss the relevance of muscle strength for youth physical development. The second purpose is to report evidence on the effectiveness of RT on muscular fitness (muscle strength, power, muscle endurance), on movement skill performance and injury prevention in youth. There is evidence that RT is effective in enhancing measures of muscle fitness in children and adolescents, irrespective of sex. Additionally, numerous studies indicate that RT has positive effects on fundamental movement skills (e.g., jumping, running, throwing) in youth regardless of age, maturity, training status, and sex. Further, irrespective of age, sex, and training status, regular exposure to RT (e.g., plyometric training) decreases the risk of sustaining injuries in youth. This implies that RT should be a meaningful element of youths’ exercise programming. This has been acknowledged by global (e.g., World Health Organization) and national (e.g., National Strength and Conditioning Association) health- and performance-related organizations which is why they recommended to perform RT as an integral part of weekly exercise programs to promote muscular strength, fundamental movement skills, and to resist injuries in youth. N2 - Die aktuelle Literatur zum Krafttraining mit Kindern und Jugendlichen zeigt eindrücklich, dass ein altersgerechtes und fachlich angeleitetes Krafttraining eine sichere, freudvolle und effektive Maßnahme für die Leistungsentwicklung (z. B. Muskelkraft, Schnellkraft, Sprintgeschwindigkeit) und Gesundheitserhaltung (z. B. Verletzungsprävention) von Heranwachsenden darstellt. Einerseits ist es das Ziel dieses narrativen Übersichtsartikels, die Relevanz der Muskelkraft für die körperliche Entwicklung von Heranwachsenden zu diskutieren. Andererseits sollen aktuelle Befunde zur Effektivität von Krafttraining auf die muskuläre Fitness (Maximal-/Schnellkraft, Kraftausdauer), elementare Bewegungsfertigkeiten (z.B. Springen, Rennen, Werfen) sowie die Verletzungsprävention bei Kindern und Jugendlichen beschrieben werden. Die aktuelle Literatur belegt, dass Krafttraining die Muskelkraft, die Schnellkraft und die Kraftausdauer von Kindern und Jugendlichen unabhängig vom Geschlecht verbessern kann. Weiterhin zeigen Studien, dass trainingsbedingte Verbesserungen der muskulären Fitness auf elementare Bewegungsfertigkeiten transferieren. Diese Wirkungen sind unabhängig vom Alter, der biologischen Reife, dem Trainingsstatus und dem Geschlecht der Trainierenden. Zudem verringert regelmäßiges Krafttraining das Verletzungsrisiko der Heranwachsenden unabhängig von Alter, Geschlecht und Trainingsstatus. Aufgrund dieses breiten Wirkungsspektrums sollte Krafttraining ein elementarer Bestandteil des Trainings von Heranwachsenden darstellen. Nationale (National Strength and Conditioning Association) sowie internationale (Weltgesundheitsorganisation) gesundheits- und leistungsorientierte Standesgesellschaften haben die positiven Wirkungen von Krafttraining erkannt und in ihre Bewegungsempfehlungen für Kinder und Jugendliche übernommen. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 730 KW - muscle strength KW - muscle power KW - strength training KW - children KW - adolescents KW - Maximalkraft KW - Schnellkraft KW - Widerstandstraining KW - Kinder KW - Jugendliche Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-526912 SN - 1866-8364 IS - 3 ER - TY - JOUR A1 - Chaabene, Helmi A1 - Lesinski, Melanie A1 - Behm, David George A1 - Granacher, Urs T1 - Performance- and healthrelated benefits of youth resistance training T1 - Leistungs- und gesundheitsbezogene Wirkungen von Krafttraining mit Heranwachsenden JF - Sports Orthopaedics and Traumatology N2 - Performance- and healthrelated benefits of yoThere is ample evidence that youth resistance training (RT) is safe, joyful, and effective for different markers of performance (e.g., muscle strength, power, linear sprint speed) and health (e.g., injury prevention). Accordingly, the first aim of this narrative review is to present and discuss the relevance of muscle strength for youth physical development. The second purpose is to report evidence on the effectiveness of RT on muscular fitness (muscle strength, power, muscle endurance), on movement skill performance and injury prevention in youth. There is evidence that RT is effective in enhancing measures of muscle fitness in children and adolescents, irrespective of sex. Additionally, numerous studies indicate that RT has positive effects on fundamental movement skills (e.g., jumping, running, throwing) in youth regardless of age, maturity, training status, and sex. Further, irrespective of age, sex, and training status, regular exposure to RT (e.g., plyometric training) decreases the risk of sustaining injuries in youth. This implies that RT should be a meaningful element of youths’ exercise programming. This has been acknowledged by global (e.g., World Health Organization) and national (e.g., National Strength and Conditioning Association) health- and performance-related organizations which is why they recommended to perform RT as an integral part of weekly exercise programs to promote muscular strength, fundamental movement skills, and to resist injuries in youth.uth resistance training N2 - Die aktuelle Literatur zum Krafttraining mit Kindern und Jugendlichen zeigt eindrücklich, dass ein altersgerechtes und fachlich angeleitetes Krafttraining eine sichere, freudvolle und effektive Maßnahme für die Leistungsentwicklung (z. B. Muskelkraft, Schnellkraft, Sprintgeschwindigkeit) und Gesundheitserhaltung (z. B. Verletzungsprävention) von Heranwachsenden darstellt. Einerseits ist es das Ziel dieses narrativen Übersichtsartikels, die Relevanz der Muskelkraft für die körperliche Entwicklung von Heranwachsenden zu diskutieren. Andererseits sollen aktuelle Befunde zur Effektivität von Krafttraining auf die muskuläre Fitness (Maximal-/Schnellkraft, Kraftausdauer), elementare Bewegungsfertigkeiten (z.B. Springen, Rennen, Werfen) sowie die Verletzungsprävention bei Kindern und Jugendlichen beschrieben werden. Die aktuelle Literatur belegt, dass Krafttraining die Muskelkraft, die Schnellkraft und die Kraftausdauer von Kindern und Jugendlichen unabhängig vom Geschlecht verbessern kann. Weiterhin zeigen Studien, dass trainingsbedingte Verbesserungen der muskulären Fitness auf elementare Bewegungsfertigkeiten transferieren. Diese Wirkungen sind unabhängig vom Alter, der biologischen Reife, dem Trainingsstatus und dem Geschlecht der Trainierenden. Zudem verringert regelmäßiges Krafttraining das Verletzungsrisiko der Heranwachsenden unabhängig von Alter, Geschlecht und Trainingsstatus. Aufgrund dieses breiten Wirkungsspektrums sollte Krafttraining ein elementarer Bestandteil des Trainings von Heranwachsenden darstellen. Nationale (National Strength and Conditioning Association) sowie internationale (Weltgesundheitsorganisation) gesundheits- und leistungsorientierte Standesgesellschaften haben die positiven Wirkungen von Krafttraining erkannt und in ihre Bewegungsempfehlungen für Kinder und Jugendliche übernommen. KW - muscle strength KW - muscle power KW - strength training KW - children KW - adolescents KW - Maximalkraft KW - Schnellkraft KW - Widerstandstraining KW - Kinder KW - Jugendliche Y1 - 2020 VL - 36 IS - 3 PB - Elsevier CY - Amsterdam 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 - 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 - 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 - TY - GEN 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 T2 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 741 KW - internal load KW - heart rate KW - linear sprint KW - aerobic power KW - football Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-540440 SN - 1866-8364 SP - 1 EP - 12 PB - Universität Potsdam CY - Potsdam 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 - 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 - 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 - GEN A1 - Jebabli, Nidhal A1 - Granacher, Urs A1 - Selmi, Mohamed Amin A1 - Al-Haddabi, Badriya A1 - Behm, David George A1 - Chaouachi, Anis A1 - Haj Sassi, Radhouane T1 - Listening to preferred music improved running performance without changing the pacing pattern during a 6 minute run test with young male adults T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe N2 - Several studies have investigated the effects of music on both submaximal and maximal exercise performance at a constant work-rate. However, there is a lack of research that has examined the effects of music on the pacing strategy during self-paced exercise. The aim of this study was to examine the effects of preferred music on performance and pacing during a 6 min run test (6-MSPRT) in young male adults. Twenty healthy male participants volunteered for this study. They performed two randomly assigned trials (with or without music) of a 6-MSPRT three days apart. Mean running speed, the adopted pacing strategy, total distance covered (TDC), peak and mean heart rate (HRpeak, HRmean), blood lactate (3 min after the test), and rate of perceived exertion (RPE) were measured. Listening to preferred music during the 6-MSPRT resulted in significant TDC improvement (?10%; p = 0.016; effect size (ES) = 0.80). A significantly faster mean running speed was observed when listening to music compared with no music. The improvement of TDC in the present study is explained by a significant overall increase in speed (main effect for conditions) during the music trial. Music failed to modify pacing patterns as suggested by the similar reversed “J-shaped” profile during the two conditions. Blood-lactate concentrations were significantly reduced by 9% (p = 0.006, ES = 1.09) after the 6-MSPRT with music compared to those in the control condition. No statistically significant differences were found between the test conditions for HRpeak, HRmean, and RPE. Therefore, listening to preferred music can have positive effects on exercise performance during the 6-MSPRT, such as greater TDC, faster running speeds, and reduced blood lactate levels but has no effect on the pacing strategy. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 696 KW - RPE KW - work-rate distribution KW - blood lactate KW - aerobic exercise Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-471884 SN - 1866-8364 IS - 696 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 - GEN 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 T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 662 KW - biological maturation KW - reliability KW - validity KW - performance KW - physiology KW - maturity KW - injury KW - talent Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-480268 SN - 1866-8364 IS - 662 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 -