ABSTRACT

Humanmovements and their results depend on various factors. One of these is the work of muscles making a dynamic structure of movement act (Brown, 2000). The second one is the fact that isometric contraction is present in every movement or every physical action. A man is always aware of movement regulation with the help of the only directly regulating force –muscle dynamic force. However, muscle co-ordination mainly depends on muscle tension co-ordination, which occurs in separate muscle group tension and action duration control, which leads to the most optimal execution of movement. The aim of this research was to investigate the differentiation of isometric contraction – how the ability to evaluate muscle tension at the load of 25 per cent, 50 per cent and 75 per cent of the maximal training load changes in different movements (flexion and extension) in 12-15year-old boys and girls. Separate muscle groups (upper arm and forearm, trunk, thigh, calf flexors and extensors) were analysed.