Hydrochloride of beta-phenylglutamic acid (RGPU-135, glutarone, neuroglutamine) administered in dosis 13 mg/kg and 26 mg/kg doses increases exercise performance of outbred mice in repeated forced dynamic load test, reduces the intensity of fatigue, and accelerates adaptation to loading. In contrast, beta-phenylethylamine (20 mg/kg) under the same conditions decreases the exercise performance and adaptation capacity and accelerates the development of fatigue. The RGPU-135 compound, similar to typical psychostimulants, in a dose of 26 mg/kg increases the spontaneous motion activity of inbred C57BL/6 mice with the active phenotype of stress response, but not in the BALB/c line mice with the passive phenotype. The RGPU-135 exhibits a psychostimulant activity without an "exhaustive" effect characteristic of psychostimulants.