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Blood Flow Restriction Training

Training with Injury

Are you going nuts because you’re injured and can’t train? Depending on your injury you may have been told by your physical therapist that you can’t put excessive stress on the affected joint/muscle, which essentially means your normal weights routine is out of the question. However, there is a way to train with an injury at a much lower intensity that has the potential to elicit the same physiological response as normal training. How you ask? The answer is called blood flow restricted training or BFR. In a nutshell, this novel form of training involves the use of a blood occlusion device strapped proximally to the working muscle to restrict blood flow while training at approximately 20-30% of your 1RM.

More detailed information on BFR is provided in an accompanying article: Muscle Building Tips, however, this article will focus specifically on how BFR training can help boost growth hormone and muscle hypertrophy, two very important factors that can help speed recovery following an injury. BFR exercise is well suited to athletes carrying an injury because it can be performed at much lower intensities than traditional weight training.

Effect of Blood Flow Restriction Training on Growth Hormone

One of the first studies to be published linking BFR resistance exercise with pronounced growth hormone release appeared in 2000. Conducted by Japanese researchers, it showed that following 5 sets of seated leg extensions (each set consisting of 14 reps performed at 20% 1RM) plasma growth hormone concentration reached a level ∼290 times as high as that of the resting level 15 min after the exercise1. Professor Jill Kanaley and her colleagues from the Department of Exercise Science at Syracuse University, New York, are another group to have established the dramatic impact that BFR exercise can have on growth hormone release and muscle growth. They published a study in 20062 showing that five sets of knee extension resistance exercise at 20% maximal isometric strength with a thigh occlusion device resulted in an acute ninefold increase in serum GH. Likewise, a different group of researchers from Texas found that low-intensity resistance exercise at 30% 1RM with a blood flow restriction device lead to a fourfold increase in serum growth hormone, which was significantly more than that observed for higher-intensity (70% of maximal strength) resistance exercise without BFR3. With at least three independent groups of researchers around the world showing a positive link, BFR resistance exercise is a great tool to boost growth hormone levels to help speed repair and recovery following an injury.

Effect of Blood Flow Restriction Training on Muscle Growth

To add to the fascinating link between BFR resistance exercise and growth hormone release, studies have also found it can have a dramatic impact on muscle growth. The first study to highlight this was reported by Fujita and his colleagues from the University of Tokyo, Japan. They found that four sets of BFR knee extension resistance exercise resulted in a 46% increase in mixed muscle fractional synthetic rate, which is a measure of amino acid synthesis into protein4. To add to this, animal studies have shown increases in muscle cross sectional area with BFR protocols5. Numerous other studies have also confirmed that BFR exercise results in favourable changes at the molecular level, which relate to muscle growth. These include nitric oxide synthesis, myostatin expression and levels of heat shock proteins; molecules known to play a significant role in muscle protein formation19.

Blood Flow Restriction Training Regimes

Most studies examining the effects of BFR resistance exercise have used exercise protocols that typically involve the use of multiple sets performed until volitional fatigue with short rest periods of 1-2 minutes between sets. For the most part, these studies have used simple single-joint exercises such as knee extension2, 15, 16, calf raises3, 17, leg curls14 and bicep curls3, however, some studies have also shown increased muscle growth when using more complex multi-joint exercise such as bench press6, 18 and squat14 in conjunction with BFR.

Even if you have an injury that doesn’t allow you to put any substantial force on your limbs, other than walking, BFR exercise can still be of benefit. A couple of studies have shown an increase in muscle size simply by using a BFR device when walking7-10. Who would have thought you could build muscle mass just by walking!

Blood Flow Restriction for Injury Management (Rehabilitation)

Even if you happen to have an injury that won’t permit you to do any form of training, be it light weights or walking, BFR on its own can be used to help speed the process of recovery and minimise the loss of muscle mass associated with injuries that require immobilisation. As an example, one study has observed that applying BFR to patients following anterior cruciate ligament reconstruction surgery effectively diminished the post operation disuse atrophy of the knee extensors11. Yet another study found that by applying BFR to a cast immobilised limb not only attenuated decreases in muscle size but also muscle strength12. Lastly, a recent study was published showing that addition of BFR to a post-operative knee rehabilitation program resulted in significant acceleration of recovery for a 19-year-old female provincial level soccer player following hamstring tendon autograft anterior cruciate ligament arthroscopic reconstructive surgery.


Occlusion or BFR training is applicable for those who are unable to sustain high loads due to joint pain, postoperative patients, cardiac rehabilitation, athletes who are unloading, and even astronauts. This form of training allows you to still make gains using light weights, while giving your joints, ligaments, and tendons a break from heavy lifting.

1. Takarda U, et al. Rapid increase in plasma growth hormone after low-intensity resistance exercise with vascular occlusion. Journal of Applied Physiology. 2000;88(1):61-65.
2. Pierce JR, et al. Growth hormone and muscle function responses to skeletal muscle ischemia. J Appl Physiol. 2006;101:1588–1595.
3. Reeves GV, Kraemer RR, Hollander DB, et al. Comparison of hormone responses following light resistance exercise with partial vascular occlusion and moderately difficult resistance exercise without occlusion. J Appl Physiol. 2006;101:1616–1622.
4. Fujita S, Abe T, Drummond MJ, et al. Blood flow restriction during low-intensity resistance exercise increases S6K1 phosphorylation and muscle protein synthesis. J Appl Physiol. 2007; 103:903-910.
5. Kawada S & Ishii N. Changes in skeletal muscle size, fibre-type composition and capillary supply after chronic venous occlusion in rats. Acta Physiol. (Oxf). 2008;192:541-549.
6. Yasuda T, Fujita S, Ogasawara R, et al. Effects of low-intensity bench press training with restricted arm muscle blood flow on chest muscle hypertrophy: a pilot study. Clin Physiol Funct Imaging. 2010;30(5):338-343.
7. Ozaki H, Sakamaki M, Yasuda T, et al. Increases in thigh muscle volume and strength by walk training with leg blood flow reduction in older participants. J Gerontol A Biol Sci Med Sci. 2011b;66:257–263.
8. Ozaki H, et al. Effects of 10 weeks walk training with leg blood flow reduction on carotid arterial compliance and muscle size in the elderly adults. Angiology. 2011;62(1):81-6.
9. Abe T, et al. Muscle size and strength are increased following walk training with restricted venous blood flow from the leg muscle, Kaatsu-walk training. J Appl Physiol. 2006;100(5):1460-1466.
10. Abe T, et al. Effects of low-intensity walk training with restricted leg blood flow on muscle strength and aerobic capacity in older adults. J Geriatr Phys Ther. 2010;33(1):34-40.
11. Takarada Y, et al. Applications of vascular occlusion diminish disuse atrophy of knee extensor muscles. Med Sci Sports Exerc. 2000;32:2035-2039.
12. Kubota A, et al. Prevention of disuse muscular weakness by restriction of blood flow. Med Sci Sports Exerc. 2008;40:529-534.
13. Lejkowski PM, et al. Utilization of vascular restriction training in post-surgical knee rehabilitation: a case report and introduction to an under-reported training technique. J Can Chiropr Assoc. 2011;55(4):280–287.
14. Abe T, et al. Skeletal muscle size and circulating IGF-1 are increased after two weeks of twice daily ‘KAATSU” resistance training. Int J Kaatsu Training Res. 2005;1:6-12.
15. Takano H, et al. Hemodynamic and hormonal responses to a short-term low-intensity resistance exercise with the reduction of muscle blood flow. Eur J Appl Physiol. 2005;95:65–73.
16. Kacin A & Strazar K. Frequent low-load ischemic resistance exercise to failure enhances muscle oxygen delivery and endurance capacity. Scand J Med Sci Sports. 2011:21:e231–e241.
17. Suga T, et al. Effect of multiple set on intramuscular metabolic stress during low-intensity resistance exercise with blood flow restriction. Eur J Appl Physiol. 2012;112:3915–3920.
18. Yasuda T, et al. Combined effects of low-intensity blood flow restriction training and high-intensity resistance training on muscle strength and size. Eur J Appl Physiol. 2011;111:2525–2533.
19. Manini TM & Clark BC. Blood flow restricted exercise and skeletal muscle health. Exercise and Sport Sciences Reviews. 2009;37(2):78-85.

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