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Objective: Muscle power is essential for the activities of daily living. Muscle power production depends on numerous factors such as muscle size and length, muscle architecture and fiber type and varies with age during growth. The association between muscle power output during a jump and lower limb muscle volume and length in adolescents is largely unknown. This study determined the relationships between muscle power developed during a countermovement jump with lower limb muscle volume and length in adolescents aged between 16 and 19 years. Methods: Forty healthy adolescent males (n = 20) and females (n = 20) aged 16 to 19 years underwent a counter-movement jump (CMJ) test. Muscle power (MP) during the jump was calculated using the Gomez-Bruton equation. Lower limb muscle volume (MV) and length were calculated in both sexes using anthropometric methods. Pearson correlation was used to assess the associations between variables. Independent-sample t -tests were used to compare anthropometric and muscle performance data between males and females. Cohen's d was used to determine the size of the differences. Results: There were differences in all anthropometric variables between males and females (p < 0.001). CMJ height (d = 4.45; p = 0.001) and MP (d = 4.74; p = 0.001) were greater in males than in females (p < 0.001). These differences persisted when jump performance was normalized to the MV (d = 1.05; p = 0.01) and length (d = 4.07; p = 0.001). There were correlations between MV and MP for males and females, with a significant correlation between limb length and MP for males (r = 0.55; p = 0.002). Conclusions: This study indicates that MV and length are associated with MP production during a CMJ in adolescents aged between 16 and 19 years, suggesting that these factors may be important determining factors for vertical jumping performance during adolescence. The sex-differences in jump performance variables persisted after normalization by MV and length, suggesting that MV and length did not entirely explain the sex difference in muscle power output during a CMJ. [ABSTRACT FROM AUTHOR]

Obesity, which is characterized by excessive body fat, increases the risk of chronic diseases, such as type 2 diabetes, cardiovascular diseases, and certain cancers. Sarcopenia, a decline in muscle mass, is also associated with many chronic disorders and is therefore a major concern in aging populations. Body composition analysis is important in the evaluation of obesity and sarcopenia because it provides information about the distribution of body fat and muscle mass. It is also useful for monitoring nutritional status, disease severity, and the effectiveness of interventions, such as exercise, diet, and drugs, and thus helps assess overall health and longevity. Computed tomography, magnetic resonance imaging, and dual-energy X-ray absorptiometry are commonly used for this purpose. However, they have limitations, such as high cost, long measurement time, and radiation exposure. Instead, bioelectrical impedance analysis (BIA), which was introduced several decades ago and has undergone significant technological advancements, can be used. It is easily accessible, affordable, and importantly, poses no radiation risk, making it suitable for use in hospitals, fitness centers, and even at home. Herein, we review the recent technological developments and clinical applications of BIA to provide an updated understanding of BIA technology and its strengths and limitations., (© 2024 World Obesity Federation.)