Up to the 1990s, several national and international scientific associations (e.g., American Academy of Pediatrics), researchers, and medical doctors were critical with regards to the application of strength training in youth. It was suggested that due to low levels of circulating androgens (e.g., testosterone) strength training is not effective in inducing strength gains in particularly prepubertal children. Furthermore, it was argued that strength training may cause damage to epiphysis or growth plates and may thus hinder maturational processes. Of note, the epiphysis is particularly vulnerable in the juvenile skeleton because the resilience of cartilage to external encumbrances is lower compared to the resilience of bone. Therefore, it was argued that damage of the cartilage area might cause the epiphysis to fuse, resulting in limb deformity and/or cessation of limb growth. With the advance of research, there was evidence that a properly designed and professionally supervised strength training program is effective in inducing significant performance enhancements in proxies of physical fitness in youth. Today, the importance of strength training for long-term athlete development in general, and sport-specific performance enhancement, motor skill learning, and injury prevention in particular has been acknowledged by coaches, practitioners, and researchers. However, there is only limited evidence-based information available in the literature with regards to the effectiveness of strength training in youth athletes.
A few years ago, the German Federal Institute of Sport Science (BISp) recognized this void in the literature by inviting experts in the field of exercise and movement sciences to two conferences on the topic strength training in youth athletes. Three years later, expert reviews (Behringer et al., 2010; Hartmann et al., 2010) were published. In 2012, a position stand entitled Strength Training in Youth Athletes was published by a number of renowned researchers in the field and supported by different scientific associations (i.e., Deutsche Gesellschaft für Sportmedizin und Prävention, Deutsche Vereinigung für Sportwissenschaft, Gesellschaft für orthopädisch-traumatologische Sportmedizin, Gesellschaft für pädiatrische Sportmedizin). Based on these activities, the German Strategic Assembly of the Scientific Athletic Association (“Strategieausschuss des Wissenschaftlichen Verbundsystems im Leistungssport [WVL]”) initiated in 2013 a call for proposals on Strength Training in Youth Athletes. In September 2014, the University of Potsdam (principal investigator: Prof. Dr. Urs Granacher, Division of Training and Movement Sciences) was announced as the leading authority that receives funding to conduct a 4 year research project on the effectiveness of Strength Training in Youth Athletes.
The respective study design comprises three work packages (see Figure 1) that will be investigated by an interdisciplinary consortium including scientific and non-scientific collaborators.
In the 1st work block (Monitoring of Training), a non-experimental design will be used to evaluate workload (e.g., duration, volume, frequency, and intensity of training) during strength training over a period of 2 years. This includes a) the documentation of training workload and athletic performance using a web-based data registration system, b) the assessment of expert knowledge on strength training in youth athletes, and c) a systematic literature search and meta-analysis on dose-response relationships following strength training in youth athletes (see Figure 1). Prepubertal and pubertal athletes in the long-term athlete development stages “Learning to Train” and “Training to Train“ will be investigated.
In the 2nd work block (Assessment of Training), a quasi-experimental design will be used a) to determine tolerance of training stress, b) to determine dose-response relations of strength training on strength and athletic performance, and c) to develop and validate strength tests that can be used in the field (duration: 2 years). This includes the application of quantitative performance assessments under field conditions (see Figure 1). Tests will be conducted 4 times per year in prepubertal (i.e., “Learning to Train” stage) and pubertal (i.e., “Training to Train” stage) athletes from different sport disciplines (i.e., ball games, combat sports, weight-lifting, gymnastics).
In the 3rd work block (Design and Evaluation of Training), an experimental design will be used to determine the effects of strength training on proxies of strength/power, motor skills, and sport-specific performance. Using the results from our systematic literature search and meta-analysis together with the findings from work packages 1 and 2, we will develop alternative long-term strength training programs (i.e., 2 years of training) and compare those to traditional training programs (see Figure 1). Strength training programs will be conducted with pubertal athletes in the long-term athlete development stages “Training to Train” and “Training to Compete” from four different sport disciplines (i.e., handball, judo, weight-lifting, gymnastics).
The German Federal Institute of Sport Science (BISp) funded the 4 year research project “Strength Training in Youth Athletes” with an amount of 1.6 million EURO. The principal investigator is Prof. Dr. Urs Granacher (Division of Training and Movement Sciences, University of Potsdam). The interdisciplinary scientific consortium consists of the following institutions and researchers (see Figure 2): Prof. Dr. Adamantios Arampatzis (Division of Training and Movement Sciences, Humboldt-University Berlin), Prof. Dr. Holger Gabriel (Department of Sports Medicine and Health Promotion, Friedrich-Schiller-University Jena), Prof. Dr. Ralf Brand (Division of Sport and Exercise Psychology, University of Potsdam), Prof. Dr. Georg N. Duda (Berlin-Brandenburg Center for Regenerative Therapies, Charité-Universitätsmedizin Berlin), Prof. Dr. Carsten Perka (Department of Musculoskeletal Surgery, Charité Universitätsmedizin Berlin, Prof. Dr. Albert Gollhofer (Institute of Sport and Sport Science, Albert-Ludwigs-University Freiburg), Prof. Dr. Wilfried Alt (Division of Sports Biomechanics and Sports Biology), and Dr. Antje Hoffmann (Division of Junior Elite Sports, Institute of Applied Training Sciences Leipzig). Additional non-scientific collaborators are: Sports Associations of the states Berlin, Brandenburg, and Thuringia, Olympic Centers, Federal Elite Sports (e.g., Bundesverband Deutscher Gewichtheber, Deutscher Handballbund, Deutscher Judo-Bund, Deutscher Kanu-Verband, Deutscher Turner-Bund), primary and secondary schools emphasizing on elite sports education and Ministries of the states Berlin, Brandenburg, and Thuringia.
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Hartmann, U., Platen, P., Niessen, M. et al. (2010). Krafttraining im Nachwuchsleistungssport unter besonderer Berücksichtigung von Ontogenese, biologischen Mechanismen und Terminologie (Wissenschaftliche Expertise des BISp; Bd. 1). Köln: Sportverlag Strauß.
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