Joint mobility and the oscillation characteristics of muscle.

The aim of this study was to investigate which muscle characteristics of oscillation of the lower extremities have influence on trunk forward flexion and knee extension. The frequency and the decrement of damped oscillation of the muscles m. rectus femoris, m. biceps femoris, m. semitendinosus and t. semimembranosus in relaxed, contracted or stretched states were recorded by the myometer among the 22 first-year male students of the department of physical education. The subjects were divided twice into two groups according to: 1) the values of the trunk forward flexion, and 2) the values of the knee extension range of motion. The oscillation frequency of m. rectus femoris of the groups with high trunk forward flexion and high knee extension range of motion was lower than in groups with less range of motion. The similarity was followed in the decrement of m. semitendinosus. The difference between the decrements of the relaxed and stretched state of m. semitendinosus and the decrement of the relaxed state of the same muscle tendon correlated with the knee extension range of motion (r=0.46 and r=0.48, P<0.05). The relationship between the decrement of the relaxed state of m. biceps femons and the range of motion was r=-0.51 (P<0.01). The results of this study showed that the characteristics of the damped oscillation as indirect parameters of viscoelastic properties of the muscles were related to the joint mobility.