We studied the effects of oral treatment with extracts from Rhodiola rosea (50 mg/kg) and Rhodiola crenulata (50 mg/kg) roots on the duration of exhaustive swimming and ATP content in mitochondria of skeletal muscles in rats. Treatment with R. rosea extract significantly (by 24.6%) prolonged the duration of exhaustive swimming in comparison with control rats and rats treated with R. crenullata. R. rosea extract activated the synthesis or resynthesis of ATP in mitochondria and stimulated reparative energy processes after intense exercise. Experiments proved different pharmacological characteristics of R. rosea and R. crenulata: R. rosea is most effective for improving physical working capacity.