The aim of this study was to investigate the effectiveness of mechanically activated complexes from plant substances to enhance athletes’ adaptability to intense physical activity. Methods: The object of the study was the dietary supplement Kladorod, which is based on the reindeer lichen Cladonia rangiferina and Rhodiola rosea in weight ratio of 10:1. To test the dietary supplement, we developed a special scheme for the experiment and selected 10 elite athletes (boxers and mixfighters). Athletes were divided into 2 groups and were under the same conditions (nutrition, medical monitoring, living conditions and training process). Athletes of the experimental group were given the dietary supplement Kladorod (capsule of 0.4 g by mouth between meals 4 times a day for 28 days). The control group was given placebo (Ringer-Locke powder) capsules in the same terms in a similar way. During the experiment, the athletes were medically examined 3 times: at the beginning, in the middle, and after the course of intervention. We measured muscle performance, fat mass, muscle mass, and serum concentrations of cortisol and total testosterone. Results: It was established that during the intensive training of boxers and mixfighters for rating fights, administration of the dietary supplement Kladorod for 28 days stabilized the absolute and relative muscle mass, preventing its reduction, in comparison with the placebo group. At the same time, indicators of fat mass decreased significantly in the experimental group. After administering the course of Kladorod, we did not observe a significant decrease in testosterone/cortisol ratio, compared to the control group Thus, the use of biologically active supplements based on lichen raw materials and complexes of lichen raw materials with different plant substances enables the body to increase its adaptive potential and physical capacity.