Abstract

The aim of the study was to find if a level of hormones influenced relaxation of skeletal muscle force during menstrual cycle. Fifteen physical education students having a regular menstruation without any use of contraceptive pills were tested in ovulatory and luteal phase of menstrual cycle. Relaxation from maximal voluntary contraction was measured during knee extension and flexion using Biodyna dynamometer. The level of estradiol and progesteron were assessed using cheminoluminescent method. The following rates were calculated: early (GWR), late (GPR), most late (GKR), and maximal relaxation ratę (MGR). The estradiol and progesteron level was higher in luteal phase than in ovulatory phase. None of the relaxation indices were statistically different between ovulatory and luteal phase. During knee flexion there was a positive correlation between GKR and estradiol level (r= 0.715), and a negative between GKR and progesterone (r= -0.91). Moreover, there was a negative correlation between MGR and progesterone level (r= -0.705). For knee extensors, there was not found any significant correlation. The result suggest that although there was no changes in relaxation indices between ovulatory and luteal phase of menstrual cycle, the level of progesterone and estradiol might influence the different phases of relaxation indices during knee flexion, but not extension. Verf.-Referat