Abstract
The relationship between structural and functional of parameters of skeletal muscles in young athletes needs further observations. The analyses of their age-group differences, sexual dimorphism, asymmetry characteristics in body regions, in sports having different pattern of physical loading could serve important information in this topic. 175 elite Hungarian handball players aged between 14 and 21 years were examined in 2023. Muscle mass component of the body segments was estimated by DEXA method and muscle thickness of the anterior mid-thigh region was measured by a new ultrasonic technique. The strength of knee extensor muscles was assessed by using an isokinetic protocol (Kineosystem dynamometer). A strong association between muscle robusticity and strength in the thigh region was confirmed in males, but not in females. Asymmetry in muscle mass reflected in the asymmetry in the knee extensor strength. A new predictive equation of muscle mass in the jumping leg and the total body from the muscle thickness in the anterior mid-thigh region of jumping leg was introduced. The exploration and understanding of asymmetric structural and functional adaptations can help athletes and trainers in planning the training and training interventions to reduce the risk of injuries.