Using novel techniques to increase muscular strength: Hypoxia and blood flow restriction

Abstract

For decades high mechanical loading has guided exercise prescription that aimed to induce muscle hypertrophy resulting in strength gain. The American College of Sports Medicine recommends resistance training loads aimed at increasing strength should be at least 70% of 1 repetition maximum (1RM). Such recommendations have come about from the many studies over the years that have shown that high-load resistance exercise training results in skeletal muscle fiber hypertrophy, whereas no significant increase has been observed when training with low-load resistance. However, training at ≥70% 1RM is difficult for some (injured, post-operative or rehabilitating patients, elderly and chronic fatigue sufferers) and other avenues for successful resistance training are required. In the 1960’s a Japanese sport scientist by the name of Yoshiaki Sato found that strength training with the addition of pressure (variously named kaatsu, vascular occlusion or blood flow restriction training) produced similar results to traditional high-load resistance training. In 2000, a groundbreaking research study published by Sato’s group showed that low-load resistive training (30-50% 1RM) performed with blood flow restriction (110 mmHg) significantly increased muscle mass and strength similar to that observed when using traditional high intensity training (80% 1RM) without blood flow restriction. Apart from the increased risk that might develop from blood flow restriction to the skeletal muscles, an additional problem with this technique is that it can only be applied to the limb muscles. For this reason, our research group began to investigate whether performing resistance training in systemic hypoxia (via breathing hypoxic air) might provide similar training benefits for whole-body training sessions. This presentation will outline our recent research in the area of resistance training with blood flow restriction or hypoxia along with the proposed potential physiological mechanisms involved.