Introduction: Kotz electrostimulation is one of the treatments used in Physical therapy, both to enhance muscle mass and muscle strength. Another method used for the same purpose is to perform isometric exercises. The two treatments can also be used to change the bioelectrical activity of the muscle.Aim of research: The aim of this study was to determine which of the methods: Kotz electrostimulation or isometric exercises, has a better infuence on the tension and weight gain of rectus femoris in healthy subjects.Material and methods: 30 individuals participated in the study. Group A (n=15) was subjected to a series of 10 Kotz stimulations, group B (n=15) to isometric exercises. Thigh girth, Strength test in the form of a „chair test” and rectus femoris muscle tension was assessed.Results: In both groups statistically signifcant decrease in muscle tension and the extension of the strength test was reported. There were no statistical signifcant changes in thigh girth. Conclusions: This research allows to confrm the validity of the use of Kotz stimulations and isometric exercises in healthy subjects.