There is a lot of talk around the use of blood flow restriction (BFR) for performance, there is a plenty of literature which discusses the benefits of use of BFR combined with exercise for hypertrophy and recovery from injury, even the prevention of muscle wastage from patients that are hospitalise and incapacitated due to the adaptations to skeletal muscle (Mattocks et al., 2018; Hughes, Paton, Rosenblatt, Gissane & Patterson, 2017; Abe, Kearns & Sato, 2005). When training for hypertrophy it is recommended that you work at 65-70% of your 1RM, it is stated that the use of occlusion allows the user to train at lower loads, 30% of 1RM and yet were able to yield hypertrophic adaptation to muscle mass. (Hughes et al., 2017; Loenneke & Pujol, 2009; Mattocks et al., 2018; Bjønsen et al., 2018) From the literature it has shown that the most effective use for the occlusion cuff is round the lower limbs due to the great concentration of muscle mass compared to that of the upper body. (Loenneke & Pujol, 2009)
What is blood flow restriction?
Originate in Japan and was known as KAATSU, BFR is the partial or full restriction of blood flow to a limb through the application of pressure via an occlusion cuff or wraps. The applied pressure not only reduces in the flow entering the muscle but prevents the blood leaving allowing it to pool in the muscles. One of the early studies by Abe and colleagues (2005) looked at the effect of Kaatsu training on walking and how this would be beneficial to strength gains or changes in muscle mass. Subjects were required to walk on a treadmill with occlusion cuffs attached at the proximal end of the legs, the study lasted 3 weeks with the subjects training twice a day for a total of 14 minutes each time, this consisted of 5 x 2 min walk with 1 min rest at a pace of 50m/min. The cuffs range from 5-18cm the study by Loenneke (2009) found that the wider cuffs (13.5cm) required less pressure to provide BFR compared to that of the 5cm, from the studies discussed it is possible to see a correlation between the amount of muscle growth and cuff width.
How does it work?
The manner in which the BFR works is by the release of growth hormones (GH) due to the increase in blood lactate, plasma lactate and muscle cell lactate due to the build-up of deoxygenated blood pooling in the muscles. (Bjørnsen et al., 2018) along with the production of heat shock protein 72 (HSP72) and nitric oxide synthesis -1 (NOS-1) which improves the CSA due to the reduction of myostatin (Loenneke & Pujol, 2009)
How does it promote muscle growth?
During ischemic conditions fast twitch fibres are recruited at a lower intensity, whereas they are normally recruited during high bouts of intensity training. (Loenneke & Pujol, 2009; Hughes et al., 2017) These ischemic conditions and hypoxia induce high levels of metabolic stress on the muscles and when this is combined with mechanical tension created from resistance training it has been claimed to be the main factor for hypertrophy. (Hughes et al., 2017)
Why would you use it?
Low intensity occlusion has shown to have benefits for athletes during a de-load phase due to the minimal risk of damage to the muscles. (Loenneke & Pujol, 2009) Not only has it show to have benefit for athlete but also the elderly, whom may not have the strength to train under high intensity but yet are able to undergo the effect of higher intensity training due to the BFR. (Mattocks et al., 2018) When training at 20% 1RM with the occlusion cuff elicits the same effect as 65% 1RM without the cuff. This is important for the elderly who often suffer from loss of muscle mass and bone density due to the ageing process (Abe, Kearns & Sato, 2005), the work by Hughes and colleagues (2017) investigated the effect of BFR had on musculoskeletal rehabilitation, specifically looking at the elderly at risk of sarcopenia and those that have suffered from knee problem such as ACL reconstruction or osteoarthritis (OA). For they knew that the loss of muscle strength due to injury can be life changing. So, they looked at the effects of quad strength have on knee OA and found that the increased strength reduced pain, improved function and offset the age-related muscle loss that often suffered.
The work done by Bjørnsen and colleagues (2018) on the effects of BFR on powerlifters found a significant increase in muscle size during a 6 week periodized plan when the cuffs where use for 2 1-week blocks. They found that the combination of traditional strength training and BFR training had the optimal effect of adapting both type I and II fibres in elite lifters.
How do you use it?
For standard hypertrophy it is recommended that you perform 2-4 sets of 8-12 reps at 70% 1RM, (Dankel et al., 2016) whereas the research suggest for BFR training you only need 3-5 sets performing 75 reps total (30, 15, 15, 15) at 20-30% 1RM with 30-60 second rest between sets, once all the sets and reps are completed then the cuff can be removed.
What are the risks?
People have feared that risks involved with using BFR and occlusion cuffs lead to blood clots, muscle damage and the potential for negative effects on cardiac muscles. (Mattocks et al., 2018) but these have been found to be unsubstantial, safety should always at the for front of every sport scientist mind when conducting research and the application of stimulus. The study performed by Mattocks and colleagues took an analytical approach in to what effect different band width, material (nylon and elastic) and pressure (50-300mm Hg) will have on the body. They found that the safety risks are dramatically reduced as long as the pressure applied should be relative to the width of cuff, i.e. the wider the cuff the lower the pressure needed. Also, the amount of pressure being applied should be relative to the individual and the limb circumference i.e. the larger the circumference the more pressure required rather than on pressure for all.
Conclusion
The occlusion cuff from the literature covered has proven to increase muscle mass in the limbs undergoing BFR, benefits have been seen in patients that have undergone knee surgery in the reduction of atrophy in thigh muscles due to the incapacitation. Not only have they helped prevent atrophy in injured athlete but there has been a positive effect in astronauts who experience weightlessness, via the application of the cuff for 5mins with 3mins rest for 4-5 sets. (Loenneke & Pujol, 2009; Mattocks et al., 2018) For greater muscle growth use a wider cuff, 13.5-18cm as these have been proven to promote the most adaptation in muscle cross sectional area. The study by Abe (2005) mentioned earlier showed increases in muscle CSA with 4 days of walking with the occlusion cuff on and by 2.3, 5 and 6% at the end of the 1st, 2ndand 3rdweek respectively. They also showed an increase in hamstring strength of 8.3% after the 3 weeks. Thus, showing how quickly the onset of hypertrophic adaptation occurs with the inclusion of BFR. To enable the tendons and ligaments to strength as well a combination of both BFR training and traditional strength training is suggested as the higher intensity will allow the adaptation to occur also will promote the greatest muscle adaptation due to both type I and II fibres will be developed.
Reference:
1. Abe, T., Kearns, C. F. & Sato, Y. (2005). Muscle size and strength are increased following walk training with restricted venous blood flow from leg muscle, Kaatsu-walk training. Journal of applied physiology.100,1460-1466.
2. Bjørnsen et al., (2018). Type 1 muscle fibre hypertrophy after blood flow restricted training in powerlifters, Medicine and science in sport and exercise.288-298
3. Dankel et al., (2016). Frequency: the over looked resistance training variable for inducing hypertrophy? Sports med.
4. Hughes, L., Paton, B., Rosenblatt, B., Gissane, C. & Patterson, S. D. (2017). Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta analysis. British journal of sports medicine. 0,1-11.
5. Loenneke, J. P. & Pujol, T. J. (2009) The use of occlusion training to produce muscle hyperttophy. Strength and conditioning journal. 00(0),1-8.
6. Mattocks, K. T et al., (2018). The application of blood flow restriction: Lessons from the laboratory. Current sports medicines reports.1704, 129-134.
7. Weatherholt, A., Beekley, M., Greer, S., Urtel, M. & Mikesky, A. (2012). Modified Kaatsu training: Adaptsations and subject perceptions. Medcine and science in sport and exercise. 952-962.