Introduction: What is blood flow restriction and how does it work?
– Blood flow restriction (BFR) involves the placement of a cuff around an arm or leg in an effort to prevent venous return, or the flow of blood through the veins of the limb back to the heart, while still allowing blood to flow from the heart to the limb through the arteries. By occluding blood flow, lighter weights and lower exercise intensities can be used to achieve similar benefits to those that would be achieved with higher intensity exercise without blood flow restriction. While the exact mechanisms are unclear, when used during exercise, blood flow restriction is thought to induce both short- and long-term changes in muscle characteristics, muscular development, and overall performance. Blood flow restriction is commonly used in older patients, patients recovering from an injury, and other patients who are unable to tolerate exercising with higher loads, but it has been shown to be beneficial to athletic populations as well. The objective of this literature review was to assess the evidence of acute and longer-term adaptive responses to exercise with BFR in trained athletes.
Methods
– The authors in this literature review identified twelve papers that fit their established inclusion criteria and assessed acute and adaptive responses to different types of exercise with BFR in various athletic populations, including track and field athletes, football players, netball players, rugby players, basketball players, and ice hockey players.
Summary of Evidence
– Training responses to BFR combined with low-load resistance exercise included:
o Decrease in metabolic stress imposed on muscles during exercise
o Increase in growth hormone concentration with a decrease in the concentration of chemical indicators of muscle damage
o Increase in squat, bench press, and leg press 1-RM (depending on activity during which BFR was applied)
o Decrease in sprint and acceleration times
o Increase in muscle strength
o Increase in muscle endurance
o Increase in muscle torque production
o Increase in muscle cross-sectional area and girth
o Improved performance on sport specific physical assessments
– Training responses to BFR combined with moderate-load resistance exercise included:
o Increase in squat and bench press 1-RM
o Improved jump and sprint performance
o Increase in levels of testosterone and cortisol
– Training responses to BFR combined with low-intensity cardio included:
o Improved aerobic capacity and anaerobic power
– It should be noted that many of these studies reported that training adaptations were sport specific and varied by athletic population (i.e. endurance-dominant athletes experienced different adaptations than strength-dominant athletes). Additionally, low intensity exercise with BFR has not been shown to produce significant changes in connective tissues. For this reason, authors stressed the importance of combining low-intensity BFR exercise training with high-intensity strength training without BFR to allow proportional changes to occur in the tendons and reduce the risk of tendon injury.
Conclusion and Clinical Applications:
– BFR can be used with low-intensity resistance training to produce changes in muscle and improvements in performance in higher-level athletes.
– Exercise training with BFR should be sport specific.
– It is important to combine low-intensity BFR training with high-intensity training without BFR to continue to stress the connective tissues and reduce the risk of tendon injury.
– BFR with low-intensity exercise can be used as an adjunct during de-loading weeks or during recovery from injury.
– Exercises done with BFR should still be progressed for continued improvements.
At Physical Therapy First, we treat a variety of patient populations including well-trained athletes, recreationally active patients, post-operative patients, and deconditioned patients, all of whom blood flow restriction has been shown to help. We offer individualized therapeutic exercise and home exercise routines. During your evaluation, your therapist can further discuss blood flow restriction and how it may help you recover from an injury and improve your function.
Reference:
Scott BR, Loenneke JP, Slattery KM, Dascombe BJ. Blood flow restricted exercise for athletes: A review of available evidence. Journal of Science and Medicine in Sport. 2016; 19(5):360-367. doi:10.1016/j.jsams.2015.04.014