Training with blood flow restriction. Mechanisms, gain in strength and safety.

Blood flow restriction training has proven to be effective, but it is not well known and is limited by initially producing discomfort. Blood flow restriction (BFR) induces hypoxia and metabolic effects, as well as reduction of proteolysis and induction of anabolic processes. Growth hormone levels are regularly increased. Controversies exist concerning neuromuscular effects. Twenty-eight of 30 studies, showed an increase in strength usually associated with muscle hypertrophy in both men and women, although data for women are sparse. Initial reports exist on positive effects on bone health after measuring rises in bone markers. A gain in strength has also been reported in non-occluded muscles after BFR training. BFR without training can lead to a rise in strength and reduce atrophy in knee extensor muscles during immobilisation. Controversial results have been observed concerning changes in aerobic capacity. Up to now no standard BFR training guidelines exist. Occlusion pressure, intensity of training, number of sets and duration of a training unit remain unclear. Presently, an occlusion pressure of 150 mmHg may be recommended with an intensity of 20 % 1-repetition maximum (1 RM), and wider cuffs are more efficient than narrow ones. Between training sets BFR should be continued. Rheologic investigations after BFR have shown no evidence for increased risk of thrombosis, when studying possible contraindications. Safety aspects for older patients must be more thoroughly addressed. The low-intensity needed may establish this training method in cardiac and pulmonary patients after future research.