Effects of Ostarine and Endurance Training on Some Functional, Hematological, and Biochemical Parameters in Male Rats

Background: Non-steroidal Selective Androgen Receptor Modulators (SARMs) are currently a group of drug candidates with anabolic effects, tissue selectivity, and the potential to improve the therapeutic process in a number of socially significant diseases. There is insufficient data on their effects during exercise and on their adverse side effects. Objectives: Our objective was to examine the role of selective androgen receptor modulators for the physical working capacity of the body, hematological and biochemical parameters, and to evaluate any side effects of SARMs. We studied the effects of ostarine (S-22, MK-2866, GTx-024, Enobosarm) alone or in combination with submaximal training in sexually mature male Wistar rats. Methods: The rats used were divided into a treadmill-trained group and a sedentary group. Half of each group received either ostarine or vehicle for 8 weeks (n = 10 each). We performed functional tests and blood analysis at the end of the experiment to analyze clinical chemistry and hematological indicators. Results: Ostarine did not affect maximal sprint speed, VO2max, and running economy, while submaximal training increased these parameters. Ostarine increased total plasma cholesterol and energy expenditure and decreased plasma glucose concentration. Neither treatment changed the oxygen-carrying capacity of the blood, the respiratory quotient, the concentration of triglycerides and LDL-cholesterol, or creatine kinase. Combined treatment neutralized the negative effect of ostarine on plasma total cholesterol levels. Conclusions: Ostarine did not affect the examined hematological and physical working capacity parameters, but it changed some clinical chemistry indicators. Training improved the physical working capacity but did not affect the clinical chemistry and hematological parameters. Further research is needed to clarify other aspects of the influence of non-steroidal SARMs on the physical working capacity and possible side effects during long-term use, as their administration, along with physical activity, is becoming popular among healthy adult bodybuilders in gyms.