Nowadays while training highly qualified boxers of different weight categories unified program of training is used. At the same time, the influence of the used physical loads on boxers' organism of different weight is not studied.Testing on bicycle ergometer in a graduated load "to the limit" revealed considerable differences of adaptation among boxers of different weight categories.The received results show the necessity to create individual programs for boxers with different body weight taking into account the characteristics of athletes' functional state. Keywords-highly qualified boxers; aerobic and anaerobic functions; training; the power of the load; lactate concentration in blood.