Mechanisms of Blood Flow Restriction: The New Testament

Abstract

When restricting blood flow for the purpose of increasing or maintaining muscle fitness, the aim is to reduce the amount of arterial flow into the limb and restrict the venous flow out of the limb. Doing so has been shown to elicit positive adaptations with regards to skeletal muscle size, and strength, while some evidence also eludes to beneficial effects on vascular and bone tissue. Regarding skeletal muscle, the main benefits of blood flow restriction are the ability to stimulate increases in size and strength while avoiding the greater mechanical stress associated with traditional high-load resistance training, and the greater volumes required when exercising with low loads to failure. While the most robust benefits are observed following blood flow restriction during low-load resistance training, evidence suggests positive adaptations occur while restricting blood flow during low-intensity aerobic exercise, and perhaps even during periods of disuse in the absence of exercise. Although the exact mechanisms are unclear, most of the evidence seems to allude to cell swelling and metabolite-induced fatigue during exercise stimulating synthetic pathways that can lead to muscle growth. While the blood flow restriction stimulus has been shown to be relatively safe for participants, the practitioner should be cognizant of the relative pressure being applied to the underlying tissue. This is important as cuff type, cuff width, and limb circumference can all influence the restrictive stimulus. Therefore, to ensure a similar, safe stimulus all variables should be accounted for.