Logo KINGS 1.0
Photo: ATB

Up to the 1990s, several scientific associations (e.g., American Academy of Pediatrics), researchers, exercise physiologists, and medical doctors were skeptical as to the effectiveness and safety of resistance training with children and adolescents. The general thought that spread at the time was that due to the low levels of circulating anabolic hormones (e.g., testosterone) resistance training does not the potential to induce strength gains, particularly, in prepubertal children [1]. Additionally, it was argued that resistance training may damage epiphyseal plates which could compromise growth [2, 3]. Intensified research efforts over the past three decades provided convincing evidence that youth resistance training is safe, joyful, and effective.

Nowadays, it is widely acknowledged that a properly designed and professionally supervised resistance training program has positive effects on muscular fitness (i.e., muscle strength, muscle power, and muscular endurance), fundamental movement skills (e.g., jumping, running, throwing), and sport-specific skills (e.g., ball kicking velocity, rowing ergometer performance) in youth [5-17], irrespective of age, sex, and maturity status [8]. Additionally, there is compelling evidence that regular exposure to resistance training decreases the risk of injuries, particularly in adolescent athletes [2, 8]. Therefore, national (e.g., National Strength and Conditioning Association) and international (e.g., World Health Organisation) organisations recommend to perform resistance training as a fundamental part of youth weekly exercise program to improve muscular fitness, fundamental movement, and sport-specific skills as well as to prevent injuries [2, 9, 11, 12].

benefits of resistance training
Photo: Chaabene et al., 2020, p.6
Benefits of youth resistance on markers of performance and health as well as established dose-response relations according to Frequency, Intensity, Time, and Type. # Training intensity is difficult to specify in multicomponent training programs which is why no information can be provided due to a lack of reported data. RM: repetition maximum

First funding cycle KINGS

During the first funding cycle of the KINGS project, many research questions on the effects of resistance training on measures of physical fitness in children and adolescents have been examined in a multidisciplinary research consortium. The applied studies generated relevant findings that showed positive effects of resistance training on markers of performance and health in youth athletes (Fig. 4) [18, 20-25]. Additionally, the influence of potentially moderating factors such as sex, biological maturation, and training type were studied [6, 20-33]. Further, patterns of muscle and tendon adaptations following resistance training were examined [34-42]. Finally, aspects of psychological health (i.e., fear, anxiety, or depression) in relation to biological maturation were analysed [43]. On the basis of many cross-sectional and longitudinal studies, the KINGS model was developed [18]. It represents a conceptual framework that assigns specific resistance training types to the different stages of longterm athlete development by considering biological maturation and individual resistance training skill competency [18]. Another key publication of the first KINGS funding cycle was the aggregation of data for a number of fitness tests from over 700 youth athletes representing different sports [44]. Normative values according to sex, age, and maturity status were computed that can be used by practitioners and strength and conditioning specialists for talent identification and development.

benefits of resistance training
Photo: Chaabene et al., 2020, p.6
Benefits of youth resistance on markers of performance and health as well as established dose-response relations according to Frequency, Intensity, Time, and Type. # Training intensity is difficult to specify in multicomponent training programs which is why no information can be provided due to a lack of reported data. RM: repetition maximum


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