Optimization of training: New developments in safe strength training

The hypertrophic effect of strength training is known to be due to mechanical and metabolic stimuli. During exercises with the restricted blood supply of working muscles, i.e., under the conditions of intensified metabolic stress, the training effect may be achieved with much lower external loads (20% of one repetition maximum). The effects of 8 weeks of high-intensity (80–85% of one repetition maximum) strength training were compared to low-intensity (50% of one repetition maximum) training without relaxation. The high-intensity strength training resulted in higher increases in strength and size of the exercised muscles than training without relaxation. During high-intensity training, at the muscle cross section, an increase in the area occupied by type II fibers prevails; while, during training without relaxation, an increase in the area occupied by type I fibers prevails. An exercise session without relaxation leads to a more pronounced increase in the secretion of the growth hormone, insulin-like growth factor-1, and cortisol. The expression of gene regulating myogenesis (Myostatin) is changed in different ways after a high-intensity strength exercise session and after an exercise session without relaxation. Low-intensity strength training (50% of one repetition maximum) without relaxation is an efficient way for inducing increases of the strength and size of the trained muscles. This low-intensive type of training may be used in rehabilitation medicine, sports, and fitness.