Yet again I am really pleased to give you another guest blog on 'The Sports Physio'. This time its on Blood Flow Restriction, or 'occlusion' training. This method of strength training has been used in the body building community for a long time, with users swearing that it 'pumps up' the guns and legs immensely. However this method of training is also becoming more and more popular in the rehab world, and I must admit I have been reading up on this a lot lately, and I do find it intriguing, although I am skeptical, as usual, of its practicality and clinical utility in some populations, and if it really does what we think it does.
However, today I will let Paul Head go through the prinicples of Blood Flow Restriction training with you. Paul has just completed his MSc in Physiotherapy at Kings College London in which his thesis and research project was on occlusion training. Prior to this Paul worked as a Sports Therapist in various professional sports, and is now looking to jump ship soon and go and work over in New Zealand, their gain, our loss! So without further ado, I will pass you over to Paul.
Can we increase muscle strength with half the effort?
Improving someone’s muscular strength and size is extremely important and a key focus for physiotherapists as it is lost quickly due to inactivity but takes a very long time to come back. In my opinion one of life's biggest discrepancies!
The current ACSM guidelines for increasing strength recommend lifting loads of over 60% of your one rep max (1RM) (1). For physically challenged populations, including the elderly, arthritis sufferers and those post surgery, this load is not possible, one reason is down to pain. We are therefore left with a bit of a dilemma?!
Everybody loves an easier option and fortunately a novel method of resistance training has become prominent in the research world over the last decade which utilises loads of 20-30% of 1RM that achieves similar, significant improvements in strength as lifting 60% of 1RM (2). It is called blood flow restriction training (BFRT) also known as occlusion or kaatsu training.
It basically involves decreasing blood flow from a muscle (occluding veins) by the application of a pneumatic wrapping device around the proximal part of the target muscle. In this way, blood goes into the muscle but can't escape. It has been hypothesised that BFRT increases muscular strength and hypertrophy through a variety of mechanisms including metabolic accumulation, fast-twitch muscle fiber recruitment, increased protein synthesis and cell swelling (3,4). I wrote about this in more detail a couple of years ago here.
A big issue with this type of training is that using pneumatic wrapping devices (ie modified blood pressure cuffs) is expensive and not accessible or practical to use outside of a laboratory environment. The effectiveness of practical BFRT (PBFRT) using inexpensive elastic wraps has been researched over the last 3 years which introduces a new concept for rehabilitation for physiotherapists.
Yamanaka et al (5) and Luebbers et al (6) assessed the effectiveness of PBFRT (20% of 1RM) on muscular strength assessed by 1RM change in collegiate athletes (n=16 and n=62 respectively). Yamanaka et al (5) participants performed four sets of bench press and squat exercises and showed bench press 1RM (5.2kg; p60% of 1RM) was supplemented with PBFRT (20% of 1RM), 1RM squat measurement significantly increased compared to HIRT combined with supplementary training (20% of 1RM) without PBFRT (p
Wilson et al (7) assessed young males (n=12) performing leg press at 30% of 1RM for four sets using different PBFRT conditions. These were control= 0/10 or moderate pressure= 7/10 subjective perceived wrap tightness. The amount of PBFR was quantified by ultrasonography and at a moderate perceived wrap tightness (7/10) complete venous occlusion occurred but not arterial and at a perceived wrap tightness of 0/10 no BFR occurred. Their results showed that blood lactate, quadriceps cross-sectional area (MRI) and knee extensor muscle activity measured by EMG (mV) significantly increased in the moderate tightness (7/10) PBFRT group, with no change in the control group (0/10). This 7/10 perceived wrap tightness PBFRT application was also used by Lowery et al (8) who performed a crossover study (n=20) using PBFRT for the elbow flexors at 30% of 1RM for 30 repetitions (7/10 tightness) or 60% of 1RM for 15 repetitions (0/10 tightness) for four weeks, for a combined 8-week training duration. They showed that PBFRT and HIRT both led to significant increases in bicep hypertrophy (ultrasonography). Showing that PBFRT (30% of 1RM) resulted in the same hypertrophy gains as HIRT (60% of 1RM) without PBFR.
My critique of the above studies is that exercise technique, ie range of motion or contraction speed, was not described or standardised. This could effect some subjects having varied times under tension which in turn effect the strength gains observed. This frustrates me in a lot of intervention studies I read! Also, blinding of the outcome assessors only occurred in the Lowery study which could lead to added encouragement given to the PBFRT subjects especially during maximal strength testing, possibly effecting the results.
For my Masters I performed a study, which is currently awaiting acceptance for publishing . It looks at the effect of PBFRT during a bodyweight single leg squat exercise to fatigue on muscular strength assessed by dynamometry and attempted to improve upon the previous mentioned flaws in methodology. The exercise technique and speed was standardised and controlled and the outcome measure assessor were blinded to group allocation. One group performed the exercise with elastic wraps at a tightness of 7/10 with the controls performing the same exercise with wraps on at 0/10 tightness. The only difference we found between groups was a significant increase in quads concentric strength after 6 weeks of training in the PBFRT group but there was no difference between groups.
Place the elastic wrap as high above the target muscle as possible (eg thigh if training lower limb or arm for thr upper limb) a subjective tightness of 7/10 is the most evidence based and effective application at the moment.
The research to date that uses bodyweight exercise alone during BFRT in my opinion shows that it is not effective at increasing strength (although some papers say otherwise). However loads of 20-30% of 1RM, 15-30 reps with 30-60 sec rest between sets, has been supported by meta analytical data (2) and evidence
based training guidelines (9) to significantly increase strength from the elderly to elite athletes.
The current research on PBFRT suggests that it could provide a similar benefit to using pneumatic expensive cuffs but is certainly not definitive yet (5-8). However it is still a possible option for elderly and also post surgical patients who cannot tolerate heavy loads to aid in increasing their strength and ultimately function due to it being implemented sooner in their rehab process and possibly speeding up their recovery.
'Is it safe' I hear you cry?
Well, when I first heard about this I thought that it can't possibly be safe to cut off your blood supply! It goes against everything logical in anatomy and physiology. Quite rightly safety of BFRT has also been prevalent in the research community. A survey of over 1800 people performing BFRT reported the most common side effects to be subcutaneous haemorrhage and numbness, which were experienced by 13.1 and 1.3% of participants, respectively (10). However, these symptoms are often dissipate as the individual becomes more accustomed to this training modality. Reviews by Loenneke et al (11,12) have shown BFRT to be a safe and produce similar responses on blood pressure, blood coagulation, delayed onset of muscle soreness (DOMS) and oxidative stress that has been observed during regular resistance training. Contraindications include a history of deep-vein thrombosis, pregnancy, varicose veins, high blood pressure and cardiac disease (11,12).
Summary
Numerous studies on BFRT and the current research on PBFRT show substantial increases in muscle strength and growth when low-load lifting (20-30% 1RM) is combined with flow restriction (2,5-8). Gains are often on par with traditional heavy-load training and sometimes even greater. BFR research performed during bodyweight exercise only, suggests this load of exercise is insufficient to increase muscular strength.
Although future PBFRT research needs to perform rigorous and standardised methodologies to substantiate previous findings and a wrap tightness of 7/10 being the most effective. Clinical guidelines have been based on much less substantial evidence in the past! This method of training is easy and cheap to implement with the wraps bought for the study I performed costing £3 a pair on ebay!
It could prove to be a huge benefit for the elderly, arthritic and also post op patients to improve their strength and ultimately function in a faster way, and requiring less than half the effort of traditional resistance training methods.
I'd appreciate any feedback, comments and I’m very happy to answer any questions.
Happy occluding.
Paul Head
Blog: www.paulhead.co.uk
Twitter: @phsportsinjury
Facebook: Page
References
1, American College of Sports Medicine. Guidelines for Exercise Testing and Prescription (8th ed). Philadelphia, PA: Lippincott Williams & Wilkins, 2009. 65–66.
2, Loenneke JP, Wilson JM, Marín PJ, Zourdos MC, Bemben MG. Low intensity blood flow restriction training: a meta-analysis. Eur J Appl Physiol, 2012. 112(5): 1849-59.
3, Loenneke JP, Wilson GJ, Wilson JM. A mechanistic approach to blood flow occlusion. Int J Sports Med, 2010. 31:1–4.
4, Loenneke JP, Fahs CA, Rossow LM, Abe T, Bemben MG. The anabolic benefits of venous blood flow restriction training may be induced by muscle cell swelling. Medical Hypotheses, 2012. 78: 151–154.
5, Yamanaka T, Farley RS, Caputo JL. Occlusion training increases muscular strength in division IA football players. The Journal of Strength and Conditioning Research, 2012. 26: 2523-2529.
6, Luebbers PE, Fry AC, Kriley LM, Butler MS. The Effects of a Seven-week Practical Blood Flow Restriction Program on Well-trained Collegiate Athletes. J Strength Cond Res, 2014. 28(8): 2270–2280.
7, Wilson JM, Lowery RP, Joy JM, Loenneke JP, Walters JA, Amsden CE. Practical blood flow restriction training increases acute determinants of hypertrophy without increasing indices of muscle damage. J Strength Cond Res, 2013. 27(11): 3068–3075.
8, Lowery RP, Joy JM, Loenneke JP et al. Practical blood flow restriction training increases muscle hypertrophy during a periodized resistance training programme. Clin Physiol Funct Imaging, 2014. 34(4): 317-21.
9, Scott BR, Loenneke JP, Slattery KM, Dascombe BJ. Exercise with Blood Flow Restriction: An Updated Evidence-Based Approach for Enhanced Muscular Development. Sports Med, 2014 (epub ahead of print).
10, Nakajima T, Kurano M, Iida H. Use and safety of KAATSU training: results of a national survey. Int J KAATSU Train Res. 2006. 2 (1): 5–13.
11, Loenneke JP, Wilson JM, Wilson GJ, Pujol TJ, Bemben MG. Potential safety issues with blood flow restriction training. Scand J Med Sci Sports, 2011. 21: 510-518.
12, Loenneke JP, Thiebaud RS, Abe T. Does blood flow restriction result in skeletal muscle damage? A critical review of available evidence. Scand J Med Sci Sports, 2014. 25(4): 521-534.
Really interesting piece Adam/Paul, thanks very much. I’m surprised that there was no significant difference between the groups, but I suppose there are a number of considerations that immediately spring to mind:
1. Were the subjects regularly performing resistance training/SL squats before the intervention? I’m sure your paper identifies whether this is the case, but it would be interesting to know for readers of this blog.
2. Why did you choose the SL squat? It’s a good exercise that is used in many scenarios, but in this application where subjects are performing it to fatigue, how was this point of fatigue dentified? I’d imagine truncal stability and hip/knee frontal plane deviations may become evident before any loss in sagittal ROM (if this was used as identification of a fatigue cut-off?). Was it a subjective report of fatigue, and if so what were the implications for the technique used?
3. With a fatiguing SL squat what muscle groups are fatiguing quickest and possibly leading to termination of the set? With the greater stability demands evident in SL squatting compared to bilateral squatting or leg press, could it be that the majority muscles being fatigued are proximal to the cuff position? This is purely guesswork as understandably you’ve had to omit much of the methodology for the purpose of writing this blog post but again if it was the case, then the proposed benefits of BFR training wouldn’t be realised. This may then possibly lead to more equal increases in strength (and the apparent lack of hypertrophic changes).
4. How was hypertrophy measured? It would come as a surprise I think for most athletes training if they performed an exercise to fatigue, regularly, and found no changes in muscle mass. That’s not even taking into account dietary requirements and other factors that may influence anabolic changes. So if neither groups found any improvement in muscle size were they already very highly trained, was there insufficient stimulus (possibly the same thing), or was it a methodological issue?
Just to confirm, I really liked the blog post and agree that there are still a number of limitations in the current literature base, particularly regarding the training methods used. The topic of BFR training, I find, is fascinating and there appears to be massive potential for it’s application to rehab, especially in the populations you mentioned above. I supervised an undergraduate study last year performing BFR at the calf muscle in trained individuals, with the suggested training protocols from the literature base, and using ultrasound to measure hypertrophy. The student found significant between group differences in both hypertrophy, muscular endurance, and 1RM strength from what I can remember. Apologies for the long comment, I hope it’s of some interest.
Eoin
Hi Eoin
You make some valid points here regarding Pauls study and I will let him answer all them in detail. My comments would be that a single leg squat is a good exercise option for a patient who doesnt have access to a leg press or knee extension machine and avoids bilateral limb use which can compensate. There are studies that show effects of BFR are both proximal and distal to the tourniquet so this could confound the results and hypertrophy has been seen in low load fatigue training without BFR so I agree it is unsual that Paul didnt find it, but as you say it could be measurement error or just beyond the minimal detectable change.
Thanks for your comments
Cheers
Adam
Hi Eoin, thanks for the comment and I hope I can answer them fully for you:
1, All the subjects were male and female adults aged 23-30 and were performing physical activity (aerbic / strengthening gym based) 3-6 x week. The SL squat exercise was definitely new for some of them but none specifically had SL squats as a consistent part of their fitness sessions. We recorded their activity level prior to the study commencing but we did not control or restrict what they did outside of the supervised 2 sessions a week for 6 weeks for the duration of the intervention, which is a limitation.
2, We decided to choose the single leg squat instead of a bilateral squat because it produces it provides a stimulus to both limbs in isolation so that a dominant limb might not compensate for a weaker with a transfer in BW to their strong side etc. It is a exercise that requires no equipment and is practical to be performed anywhere. It was standardised by the target limbs foot being 10 cm away from a plinth placed behind them that was adjusted to match the angle that we required for the knee and each participant lightly touched the plinth with their backside before rising back up. The speed was controlled as 2 secs down and 2 secs up by a metronome. A subject was encouraged and supervised by 2 trainers who encouraged them to go to fatigue and this was deemed when a subject did 3 errors. This included too long a pause on the plinth, not maintaining the speed of movement or touching their contralateral foot on the floor. When a subject did 3 errors their set was ceased. We chose to go to fatigue because in the literature subjects have reported that the repetition amount commonly used of 30,15,15,15 was either too easy or too difficult for them to achieve each set so going to fatigue we maximised the volume for each individual.
3, BFR has been shown to increase metabolic accumulation above as well as below the wrap/cuff placement shown here: http://onlinelibrary.wiley.com/doi/10.1111/j.1475-097X.2012.01126.x/full. This could have affected results as you say. We progressed the knee angle from 70 -90 degrees over the training period but when at 90 degrees the glutes could have been a limiting factor and could have shown changes in strength or hypertrophy that were not measured. The SL squat also shows high EMG for the quads above 80% MVC which could have seen the no sig differences in strength when comparing groups.
4, Hypertrophy was secondary outcome for the study with strength measured by isokinetic dynamometry (because everyone does 1RM and is more accurate) nd hypertrophy was a secondary outcome and was only measured by thigh girth measurement. I know this not accurate but was used in Yamanaka (5) and Luebbers (6) studies and we did not have ultrasonagraphy or MRI available to us. We concentrated on strength changes because a lot of BFR and PBFR research focuses on hypertrophy changes but for me changes in strength are more relevant. Diet was not controlled in the study which again is a limitation. The subjects were generally active and strength changes were seen pre to post in PBFR group but not when combined. This could have been because we used isokinetic dynamometry the SD when calculating peak torque were very high making it more difficult to get significant differences and also for me BW alone unless they are very deconditioned or elderly is not enough load for significant increases in strength and muscle size, and that is backed up by the current literature if you actually read the full texts rather than take the researchers word for it.
Hope that helps any more questions just fire away. I too see a large potential especially immediate post op for this type of training.
Many thanks
Paul
Thanks Paul and Adam for the responses.
Have to agree 100% with your reasoning for the SL squat, far too many studies employ methodologies that are completely unrealistic to replicate in practice for the majority of clinicians. It’s just a pity that there may be a few too many confounding variables at play in this instance to make the results reliable. I’d love to see a similar protocol but with more focus on the technique of the SL squat. There are so many strategies one can take to complete a rep and most patient’s I see tend to rely in trunk flexion when range or fatigue become a challenge (I’m sure you’ll have seen the same).
It would also be great to see some results using BFR where an individual doesn’t have to complete 15-30reps to see a benefit over not using BFR. I’d imagine most post-op ACL pts would struggle to complete 15 SL squats initially, when that phase of rehab comes around. So could people in this situation perform shorter sets, without needing to increase the %1RM, and be confident it was more beneficial than no BFR?
If the results can be found in other exercises, using similar muscle groups with low loads (even bodyweight – I’m sure you have some of the papers regarding BFR providing results with 20mins walking,) then there doesn’t seem to be any reason why we wouldn’t see some difference between groups with this exercise, as long as the protocol is watertight. I suppose this is why so many studies up to now have looked at ‘simpler’ exercises, such as leg press, as it can be much easier to control.
Definitely a few really interesting studies could come of all this that would give us further insight into the scope of application for BFR. Thanks for the discussion gentlemen.
Eoin
Paul,
What was the isokinetic testing
Protocol used??
I completely disagree with using elastric wraps/bands as a means to achieve vascular occlusion due to high levels of variability in elasticity, applied tension etc. BFR should be performed utlizing a pneumatic device designed for such use with occlusion pressure monitored by someone who knows what they are doing.
Hi Garry
I can understand your point of view, so I wont argue much against it, however I think using a self perceived sensation of tightness with these elastic wraps seems to be comparable in the few studies I have read, and as Paul presents here. Also does the exact pressure matter, the effects will still be variable from person to person even with a pneumatic device due to a lot of other factors, such as sub cutaneous body fat for one.
I think Paul is trying to demonstrate a simple home based version of BFR that can be used without the need of expensive kit or close supervision, yes safety is important but as Paul shows there are minimal risks seen (at the moment) and of course clear instructions and parameters need to be given and taught before training commences, such as total time under occlusion etc, and also remember this has been going on for years in gyms up and down the country in the body building community without major issues as I am aware!
I’m sure Paul will have some comments as well
Cheers
Adam
Hi Garry,
I understand your comment about the high variability in elastic wraps. But it has been shown that a perceived wrap tightness of 7/10 achieves vascular occlusion that is measured by real time ultrasonography http://www.ncbi.nlm.nih.gov/pubmed/23446173. On the first session once a subject has achieved a perceived wrap pressure of 7/10 then the wrap measurement can be recorded which standardises how tight it is each session? The evidence for using elastic wraps instead of pneumatic cuffs is increasing but is no way definitive but evidence form the studies presented in this blog are promising. Also the variability as Adam mentions in mmhg pressure applied with pnuematic cuffs shows it is effective in pressures from 80mmhg up to 260mmhg it meta analytical data here: http://www.ncbi.nlm.nih.gov/pubmed/21922259 and thats quite a large range of variability and tension don’t you agree?
Any BFR programs need to be designed appropriately and the people need to be screened and checked for any contraindications or risk factors for the exercise by health care professionals before commencing. I wrote about contraindications in this blog and also in a previous one which shows the english institute of sports pre training questionnaire for BFR training here: http://paulhead.co.uk/occlusion-training-bloody-effective-at-improving-strength/.
The use of pneumatic cuffs is very expensive and the use of elastic wraps although not conclusive yet is promising and can be used a wider range of settings to possibly help benefit the largest of amount of people and patients which for me is very encouraging indeed.
Many thanks
Paul
As much as weight training raises BP, I have found since I started it my BP average is much much lower. I was given a book called Reduce Blood Pressure Through Weight Training and since then I have taken it all in and it has really worked for me. I hope I can get to the point where I can try the restriction methods, looks like they work great! That book is by Ronald Deblois, might be worth a look for those that train with high bp.
I’m currently reconditioning with the guidance of an SEM adviser and practical BFR (graded blood pressure cuffs progressing to wraps) is part of that (SLAP and meniscal tear inter alia). BFR is part of the strategy to assist me with avoiding the recommended surgery as I don’t have the time for that without it having an adverse impact on work/general life and I’m reluctant to embrace heroic intervention when something like this (in combination with mobility work) might facilitate me attaining my goals.
[I’ve removed a too long comment on why I think the cost is a substantial barrier because there is no avenue that allows for ‘trying this out’ without a huge upfront investment that might be value over time but there is no way of evaluating that at present in the UK.]
Sports Physio,
Awesome discussion! I had a question as to clinically how would you obtain a 1RM for a patient who is maybe post-op/arthritic? As was presented, it is difficult for a patient of these conditions to work at 60% of a 1RM then how could we expect to perform a maximal rep without hurting the patient?