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Strength training had long been regarded as a pastime for enthusiasts looking to increase their strength and muscle mass but we now know that methodical, structured, and measured strength training not only strengthens muscles but also keeps you physically fit and healthy. It strengthens the muscles, improves general and athletic motor skills, reduces the risk of injury, and has a positive effect on common diseases such as back pain, diabetes, and obesity. Competitive athletes can improve their overall motor skills through strength training – such as jumping, speed, and agility – as well as sport-specific skills like the power of their soccer shot or their serve speed in tennis. Until the 1990s, it was debated, however, whether strength training was beneficial for children and adolescents or whether it posed a health risk. A joint research project of the University of Potsdam with partners from science as well as athletes and coaches themselves are expected to determine the effectiveness of “Strength Training in Youth Athletes (KINGS)” and to derive specific training recommendations. The collaborative project is funded by the German Federal Institute of Sport Science (BISp) under the auspices of the research program of the German Strategic Assembly of the Scientific Athletic Association (WVL).
“The topic ‘Strength Training in Youth Athletes’ has long been neglected in research,” says Prof. Urs Granacher, PhD. The University of Potsdam exercise scientist heads the KINGS study. He argues that beginning strength training at an early age helps young athletes build up long-term resources that will develop the motor skills and constitution necessary to cope with the demands of training and competition down the road. “The precise effects in terms of increased performance and physical stress tolerance – particularly for various age groups, developmental stages, and sports – are still largely unresearched. The KINGS study is to change that,” says Granacher.
A shift in thinking began in the mid-1990s, Granacher explains. At the 1988 Summer Olympics in Seoul, the two German states were still among the best, finishing 2nd (GDR) and 5th (FRG) in the medals count. They combined for more medals than the top performer, the Soviet Union. For this reason, expectations were high after reunification that a united Germany would dominate competitive sports for years to come, but things turned out differently. Germany continuously performed worse in the medals count at major events. It quickly became clear that sustainable success will only come by starting with the youth. “Strength training seemed to be a very promising way to increase youth athletes’ performance and ensure their physical stress tolerance,” Granacher says. “The German Federal Institute of Sports Science therefore initiated a series of projects to identify research deficits and launch appropriate studies.” In the subsequent call for proposals, the joint project of the scientific consortium led by Granacher was chosen. The project brings together researchers from Humboldt Universität zu Berlin, Charité Universitätsmedizin Berlin, Friedrich Schiller University Jena, the University of Freiburg, the Institute of Applied Training Sciences Leipzig, the University of Stuttgart, and the University of Potsdam. They will spend four years evaluating training data, developing feasible procedures for measuring strength, and elaborating on and validating appropriate training programs – geared to age, gender, and sport.
This is only possible through an extensive network of sports practitioners, who will take part in collecting the necessary data and testing the training programs. Among them are state sports federations, Olympic training centers, selected top sports federations, elementary schools emphasizing sports, elite sport schools, and the Brandenburg Ministry of Education, Youth, and Sports. Only once we had all of these partners on board did important doors open for us,” Granacher explains, "because the transparent handling of training data is naturally a very sensitive issue.” It was therefore necessary to convince one or another partner and explain the project’s long-term benefit, particularly for actual implementation on the field or court.
The KINGS study is divided into three blocks: In the first, the researchers record and analyze the training data in online databases as well as expertise on strength training in competitive youth athletics. In the second block, they measure the training of young athletes in the field at specific points in the training year to deduce the dose-response relationship from their own data, the literature, and the training documentation. The third part combines the findings of the first two. The project basically develops and evaluates new gender-specific, age-specific, and sport-specific strength training programs, and the findings from all blocks are transferred directly to athletes and coaches.
The expert knowledge of coaches is the most important source for the first block of the study. “Our project proceeds from a “best practice model”. Proven experts and successful coaches in youth athletics are employed at elite sport schools, elementary schools emphasizing sports as well as professional sports associations,” says Granacher. “We initially want to collect data about the specific knowledge of coaches on ‘strength training in youth athletes’.” This is the point where the sports psychologist Prof. Ralf Brand, also from the Department of Sport and Health Sciences, comes into play. He reconstructs the expert knowledge on strength training among top coaches in a multi-part process, a so-called “Delphi study”. Conducting individual telephone interviews with coaches of various sports is the first step. The results are summarized in an interview sheet and resubmitted to experts. Finally, everyone comes together for a guided panel discussion at the University of Potsdam. “The aim is for coaches to reach a consensus on more successful and less successful measures in strength training,” says Brand.
In addition to the Delphi method, which is well established in psychology, training data are documented via an online database during the first research block. The database was originally commissioned by the Ministry of Education, Youth, and Sports of the Federal State of Brandenburg, and its content will be further developed as part of the KINGS study with regard to strength training by the Leipzig Institute of Applied Training Sciences. The athletes can enter training data themselves under the guidance of their coaches. As a result, the project is able to collect not only important data from the actual training that allow researchers to draw conclusions on what training measures generate positive effects but also to capture the variety of data and to correlate them. Age, gender, biological development, and the type of sport – the interaction of these factors ultimately determines which forms of strength training are reasonable.
This is exactly the substantial backlog Granacher’s working group has proven with a systematic analysis of the literature on previous national and international research projects. “We systematically searched the literature and conducted a meta-analysis from 1975-2015,” explains Melanie Lesinski, a PhD student involved in the project. “Past studies have proven that strength training is an effective way to increase motor skills and sport-specific performance in youth athletes.” Individual results, however, also show that their efficiency varies a lot. The examinations confirm the obvious assumption that strength training significantly increases muscle strength, but only moderately affects important variables like vertical jump, speed, agility, and sport-specific performance. A lot remains to be done in the KINGS study in terms of age, gender, and sport-specific sub-analyses. “Only very few studies have looked at the effect of strength training on young female athletes, established the biological age, and examined athletes from technical-compositional sports and combat sports,” Lesinski summarizes.
While the first block provides a baseline study on existent forms and success of youth athletic strength training, the exercise scientists are starting the experimental second work package of the project. During this part, they will be closely collaborating with colleagues from Humboldt-Universität zu Berlin, Charité Universitätsmedizin Berlin, Friedrich Schiller University Jena, and the University of Stuttgart. “We will be visiting the athletes ‘in the field’ on four selected dates in the training year to collect our own data,” Granacher explains the next steps. “We will be measuring general motor skills and sport-specific performance.” This will also involve validating field-based measurement systems with the help of comparative laboratory measurements. The goal is to develop tools for coaches to use for on-site measurements, which would allow them to draw conclusions for training.
Such a tool is the so-called “strength training watch”. It was developed by the sports scientist and biomechanic Prof. Wilfried Alt and his team at the Institute of Sport Science at the University of Stuttgart. Sensors attached to an athlete’s leg or a dumbbell count the number of repetitions and the level of exhaustion during training. The KINGS study will be creating an interface between the watch and the online training database, which will enable automatic and exact training documentation.
Based on the data from the first two blocks, the researchers will develop new training programs during the project’s third part – and test them in action. “We will introduce interventions and document them over a prolonged period, i.e. of at least two years,” Granacher explains the procedure. “We want to observe not only the change in athletic performance but also examine the various causes – such as how nerves, muscles, and tendons adapt to strength training. We will also be looking at several long-term training effects.” Project partners like Humboldt Universität zu Berlin will investigate, among other things, the effects of training on the muscle-tendon system. Specialists at Friedrich Schiller University Jena will use immunological markers to examine the influence of strength training on athletes’ susceptibility to infection. Orthopedic examinations will be performed at Charité Universitätsmedizin Berlin to be able to make concrete statements about the stress tolerance of strength training in youth athletes and determine, for example, the effects of training on joint stiffness.
"We want to develop an alternative type of strength training for youth athletes – geared to age, developmental stage, and sport”, Granacher describes the ambitious goal. This is not at all easy, as the exercise scientist explains, “If you want to help young athletes become top athletes, the training must take into account and support their biological maturity.” This means it is important to lay the foundation and develop the repertoire of movement in young athletes before beginning long-term athletic development. Sport-specific training comes later. Strength training has also to accommodate this principle and offer various movements by using a variety of methods. “The training, therefore, sometimes may not look like strength training as you imagine it, but rather very playful and suitable for children. Little equipment is used; a lot of exercises utilize their own body mass. It is also important to train the correct exercise technique, for example, using a broomstick instead of a bar,” says Granacher. “This is why we will also develop sport-specific measures together with experienced athletes and their coaches.”
This “synergy" of science and athletes and their coaches is of top priority in the KINGS study. Just as the participating research institutions can gain insight into and explore – and even develop and evaluate – current training programs thanks to the athletes and coaches involved, can also athletes and coaches benefit from the project’s results. “We strive to give regular feedback on the study’s progress and results,” says Granacher. “We report about the project on the website and provide consultation hours as well as advanced education courses on strength training for coaches.” In addition, the researchers will present their findings at meetings, in newsletters, and in scientific publications.
“The project offers a unique opportunity to boost the sometimes inadequate exchanges between sports science and athletes and their coaches to achieve with a closer, long-term collaboration,” according to project assistant Thomas Mühlbauer. “This is necessary because only in exchange with the athletes and coaches will we be able to advance our knowledge.”
Who knows, perhaps the enhanced training of tomorrow’s athletes may produce an Olympic champion or two.
Prof. Urs Granacher, PhD passed the first and second state examinations in sports science, German, and English language and literature at the University of Freiburg and the Staatliches Seminar für Didaktik und Lehrerbildung Freiburg (State Institute for Didactics and Teacher Training) where he obtained his doctorate and habilitation. He has had teaching and research assignments at the universities of Basel and Jena as well as the Memorial University of Newfoundland, Canada. Since 2012 he has been Professor of Training and Movement Sciences at the University of Potsdam.
Department für Sport- und Gesundheitswissenschaften
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Prof. Ralf Brand studied psychology and sports science at the University of Konstanz. Since 2008 he has been Professor of Sports Psychology at the University of Potsdam.
Melanie Lesinski, M.Sc. studied sports therapy and prevention as well as sports science at the University of Potsdam. Since September 2014 she has been a research associate at the Division of Training and Movement Sciences at the University of Potsdam and a PhD student in the project “Strength Training in Youth Athletes”.
Dr. habil. Thomas Mühlbauer studied sports science, specializing in rehabilitation and sports therapy, at Leipzig University, followed by teaching and research assignments at the universities of Basel and Jena as well as Texas A&M University. Since 2012 he has been a research associate at the Division of Training and Movement Sciences of the University of Potsdam.
WVL Project “Strength Training in Youth Athletes: KINGS-Study"
Academic partners: Prof. Urs Granacher (University of Potsdam, lead); Prof. Adamantios Arampatzis (Humboldt-Universität zu Berlin), Prof. Ralf Brand (University of Potsdam), Prof. Georg N. Duda (Charité Universitätsmedizin Berlin), Prof. Holger Gabriel (Friedrich Schiller University Jena), Prof. Albert Gollhofer (University of Freiburg), Prof. Wilfried Alt (University of Stuttgart), Dr. Antje Hoffmann (Institute of Applied Training Sciences Leipzig) und Prof. Carsten Perka (Charité Universitätsmedizin Berlin)
Non-academic collaborators: Sports Associations of the States Berlin and Brandenburg, Olympic Training Centers Berlin, Brandenburg, professional sports associations (Bundesverband Deutscher Gewichtheber, Deutscher Handballbund, Deutscher Judo-Bund, Deutscher Turner-Bund), elementary schools emphasizing sports, elite sport schools and ministries in Berlin, Brandenburg, and Thuringia Funded by: German Federal Institute of Sport Science (BISp)
Text: Matthias Zimmermann, Translation: Susanne Voigt
Online-Editing: Agnes Bressa
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