Restriction to blood flow first emerged as a form of exercise training with Japanese bodybuilders in 1995, but is now more commonly referred to as Blood Flow Restriction (BFR) training. Over the past 3-4 years, BFR training has exploded in popularity amongst strength & conditioning coaches and physiotherapists alike. Early research identified the capability of BFR to stimulate hypertrophy and strength gains when combined with low-load resistance training but there was a distinct lack of research on how this was happening.
Nowadays, it’s suggested from clinical research that when BFR training is combined with low-load (20-40% 1 RM) strength training (approximately 75 reps over 3-4 sets), BFR can facilitate significant strength and morphological adaptations when compared to traditional methods (60-80% 1 RM). However, practical research suggests that a combination of both low-load BFR (2-3 times/week) and high load training will result in the best adaptations and sport-specific outcomes over a 6-10 week period.
whats occuring
BFR training involves the use of non-invasive inflatable cuffs being applied to the upper thigh. This allows partial restriction of arterial blood flow to the lower limb and full restriction of venous return to the target muscle group, as veins require less pressure to fully occlude than arteries. This reduced arterial blood flow creates a hypoxic environment – a lack of oxygen.
Whilst the cuff is inflated, this causes venous pooling of blood which results in metabolite rich blood. The continuous BFR then traps this blood in the muscles during the exercise period, and thus, creates a high degree of metabolic stress. Working the muscles into failure maximises this metabolic stress. The muscle is undergoing less mechanical tension due to the reduced weight through the limb in comparison to resistance training. This combination of increased metabolic stress and reduced mechanical tension are the primary factors for muscle hypertrophy in BFR training.
To date, the definitive mechanisms explaining adaptations to low-load BFR training have not been identified in a logical manner, however proposed mechanisms include: cell swelling, increased muscle fibre recruitment and increased corticomotor excitability. Physiologically, this results in:
- Increased Type-2 muscle fibre recruitment = greater potential for strength, speed and hypertrophy changes
- Increased local growth hormone and IGF-1 levels by 200-300%
- More rapid accumulation of metabolic by-products, such as lactate
- Enhanced stimulation of muscle protein synthesis by 45-55%
WHO MIGHT BENEFIT FROM BFR?
The use of BFR training has vast potential for numerous athletes as BFR can facilitate hypertrophic and strength responses in skeletal muscle in the absence of high mechanical loads. For example, an athlete is limited to low intensity strength training after hip/knee/ankle surgery, particularly when full range of motion is reduced through a joint. In the early stages post-surgery BFR training can still commence as exercises are undertaken at a lower intensity (sets/reps) and without the requirement for full range of motion.
Certain athletes are unable to complete high load resistance training due to lower limb joint pain or restriction. Research on patients who underwent Anterior Cruciate Ligament reconstruction reported less knee pain during the rehabilitation programme, when using light load BFR training versus traditional resistance training. Only last month has research emerged that BFR training reduced pain sensitivity up to 24 hours after single-leg press exercises in patients with acute and chronic lower limb pain. However, further research is required on larger cohorts to explore this concept further.
Likewise, research is ongoing to investigate the potential benefits of BFR enhancing the removal of metabolic waste products post-exercise. When the cuff is released after strenuous exercise, the enhanced muscle oxygenation resulting from the ischemic stimulus promotes a faster return to normal muscle function as there is reduced swelling and muscle soreness. Current proposals post exercise include inflating the cuff for 5 minutes, immediately deflating it for 3-5 minutes and this is repeated 4-5 times for 30-40 minutes in order to quickly restore maximal force production.
PRECAUTIONS
Consult your Strength and Conditioning Coach, Physiotherapist or Athletic Therapist before commencing any BFR Training. There is no robust evidence that BFR carries a safety-risk, however, the use of BFR training is not recommended if you suffer from any of the following:
- Ischaemic heart disease, severe aortic stenosis and hypertrophic obstructive cardiomyopathy
- Previous cerebral haemorrhage/stroke
- A history of blood coagulation problems
- Hypertension
RECOMMENDED READING
- BINNIE, M.J. 2017. Blood flow restriction techniques for exercise performance: a review of current research and practical applications. J Aust Strength Cond, 25(3): 62-70.
- COOK et al. 2014. Improving strength and power in trained athletes with 3 weeks of occlusion training. International Journal of Sports Physiology and Performance, 9: 166-172.
- COOK et al. 2018. Neuromuscular adaptations to low-load blood flow restricted resistance training. J Sports Sci Med, 17: 66-73.
- GILES et al. 2017. Quadriceps strengthening with and without blood flow restriction in the treatment of patellofemoral pain: a double-blind randomised trial. Br J Sports Med, 51: 1688-1694.
- HUGHES, L and PATTERSON, S.D. 2020. The effect of blood flow restriction exercise on exercise-induced hypoalgesia and endogenous opioid and endocannabinoid mechanisms of pain modulation. J Appl Phys,
- HUGHES et al. 2018. Comparison of the acute perceptual and blood pressure response to heavy load and light load blood flow restriction resistance exercise in anterior cruciate ligament reconstruction patients and non-injured populations. J Phys Ther Sport, 33: 54-61.
- HUGHES et al. 2018. Influence and reliability of lower-limb arterial occlusion pressure at different body positions. Peer J, 6: 4697.
- HUGHES et al. 2017. Blood flow restriction training in clinical musculoskeletal rehabilitation: a systematic review and meta-analysis.Br J Sports Med, 51: 1003-1011.
- INGRAM et al. 2017. The influence of time on determining blood flow restriction pressure. J Sci Med Sport, 20: 777-780.
- KORAKAKIS et al. 2018. Low load resistance training with blood flow restriction decreases anterior knee pain more than resistance training alone. A pilot randomised controlled trial. J Phys Ther Sport, 34: 121-128.
MARK GALLAGHER
PHYSIOTHERAPIST
Mark is a Musculoskeletal Physiotherapist who has worked in conjunction with AXSOM Sports and Mayo GAA since 2013 and regularly implement’s BFR training with specific players & athlete’s. Whilst studying for an MSc in Physiotherapy at Robert Gordon University, Mark worked with the Aberdeen Football Club’s Academy. He previously completed a part-time MSc in Sports Medicine and Biomechanics at the University of Dundee and a BSc in Athletic Therapy and Training at Dublin City University.
