The textbook was prepared on the basis of the standard program of sports biochemistry approved by the Ministry of Higher and Secondary Specialized Education of the Republic of Uzbekistan and the Ministry of Culture and Sports of the Republic of Uzbekistan. It includes the following sections: biochemistry of muscle and muscle contraction; bioenergetic processes in muscle work; dynamics of biochemical processes in muscle work; biochemical foundations of fatigue; biochemical foundations of athletes' speed-strength qualities, endurance and methods of their development; laws of biochemical adaptation in the process of sports training; biochemical foundations of athletes' nutrition and biochemical control in sports. The textbook is intended for undergraduates and young teachers of physical education institutes. However, this textbook can also be a useful guide for students of physical education faculties of other educational institutions, all sports trainers and doctors working in the field of sports.