The factors affecting mechanical properties of skeletal muscles in the relaxed and tense state under the influence of the exercise stress (ES) were studied by a computer-assisted experimental tool (Vibratory Viskoelastometr (VVEM-05)). ES consisted of 35 jump up in place. 34 students from soccer specialization of NSU of P.F. Lesgaft participated in an experiment. The mechanical properties (elasticity and viscosity) were studied in a tense and relaxed muscle before and immediately after the ES. Factor analysis (principal component analysis) revealed three latent factors that explain 92.4% of the total sample variance. The first factor (56.4%) is bound to implication with the processes of excitation manifestation in the muscle, and with the muscle control by the nervous system. The second factor (23.2%) represents the viscosity of the skeletal muscle, and the third factor (12.7%) - skeletal muscle elasticity. Based on these results, we can conclude that mechanical properties of the evaluation must be made in the muscle relaxed state to eliminate the influence on the elasticity and viscosity indices by the nervous system.