Laser exposure stimulates cell proliferation and tissue repair. Branched-chain amino acids (BCAA) are widely used in sports medicine as a stimulator of anabolic processes. However, there is no evidence of the effect of combined laser and BCAA application on skeletal muscle morphometric characteristics during exercise in the training process.Purpose: to study the effect of infrared laser exposure in combination with amino acid at myosatellitocytes and skeletal muscle myocytes during swimming training.Material and methods. The experiment was conducted on 30 Wistar rats: Group 1 – intact, Group 2 – dynamic control (trainings with endurance swimming), Group 3 – trainings and BCAA, Group 4 – trainings and laser exposure at hip muscles (970 nm, 1 W, 60 s), Group 5 – combined exposure to laser and BCAA. Trainings were three times a week for 6 weeks; laser session was after each training. Samples of the bipedal thigh muscle were fixed with formalin; histological sections were stained with hematoxylin-eosin. The morphometric analysis of the digital image of objects with statistical processing by Mann – Whitney method was made.Results. Laser exposure combined with BCAA during trainings increased the nuclei area and the number of myosatellites and myocytes; it also enlarged the cross section of muscle fibers which was more pronounced if to compare with isolated laser irradiation of the muscle or BCAA.Conclusions. Infrared laser exposure in combination with branched-chain amino acids effectively stimulates regeneration due to hyperplasia and hypertrophy of skeletal muscular tissue, thus providing physiological adaptation in the training process.