The scientific and clinical communities have embarked on a never ending quest to determine the optimal prescription of exercise in healthy and pathological populations. That search carries over into the application of Blood Flow Restriction (BFR). It seems to be well accepted now that BFR can amplify the effects of low intensity exercise.(1–3) While the recent position stand paper provided important guidance for BFR exercise prescription in healthy persons, questions abound as to how best to apply BFR in clinical scenarios.(4) Key topics warranting continued investigation include, but are not limited to risks / contraindications, pressure selection, size and type of cuff, as well as typical exercise parameters of intensity, duration and frequency.
A recent publication out of the University of Texas attempted to contribute to this discussion by examining exercise responses to walking with wide-rigid cuffs (WR), narrow-elastic cuffs (NE), or a no restriction control group.(5)
|Details||WR Cuffs (18cm)||NE Cuffs (5cm)||No BFR Control|
|Mean Systolic BP||116mmHg (standing)||116mmHg (standing)||115mmHg (standing)|
|Pressure Used||BFR – 160mmHG||BFR – 300mmHg||N/A|
|Walking Intervals||2 min||2 min||2 min|
|Rest Intervals||1 min||1 min||1 min|
|Pace||0.9 m/s||0.9 m/s||0.9 m/s|
|Total work time||10 min||10 min||10 min|
The authors used 160 mmHg for the wide cuff condition and 300 mmHg for the narrow cuff condition. Regarding their choice of pressures they state, “These same standard pressures were used for all individuals for comparative purposes.” This assertion contrasts rather strongly with papers that have demonstrated clearly that cuff width, in addition to a subject’s individual characteristics, provide for variances in both acute and chronic study results.(6–8) Additionally, their subject pool included both men and women. Men are known to have higher limb occlusion pressures than women, thus providing yet another reason why in order to compare conditions they would need to individualize the pressures used.(9)
The results of the study were generally not surprising when considering all the variables either accounted for or not by the design. They found that the wide cuff condition significantly elevated HR, SBP, DBP, MAP, lactate, RPE, and double product (a surrogate for the amount of work the heart is doing) compared to the other conditions. Within their discussion they raise concern regarding these findings, suggesting that if a WR cuff is used in a clinical setting it could present a safety concern. In so doing, they ignore some rather important pieces to that puzzle. For one, they did not look at any other pressures with the WR cuff they used; either individualized or not. This means they can only draw a conclusion based on the singular cuff pressure condition that they examined with the WR cuff. A blanket statement regarding cuff design based on these findings is at minimum short-sighted.
Considering the width of the WR cuff, and the pressure used in relation to the mean resting systolic pressure (116mmHg) of that group, it is highly likely that at 160 mmHg more than one of the subjects was exercising at full occlusion. Exercise at full occlusion in at risk populations is not something we’ve seen anyone advocate for in the BFR space, nor is it something anyone has studied or advocated for in healthy persons. While they do report significant hemodynamic differences between the WR group and the other two groups, they fail to discuss the magnitude of these responses. Systolic BP was ~35 mmHg greater than control, DBP was ~20 mmHg greater, HR was at most 5 bpm greater and lactate increased 2 fold. The magnitude of these differences is not particularly concerning, especially when one considers the extremely well established fact that in order to elicit any sort of adaptation in human skeletal muscle, or cardiovascular function, increases such as these are likely at the low end of that threshold.(10)
Unfortunately, this article doesn’t contribute valuable information toward the continued pursuit of optimal BFR exercise prescription in healthy persons, much less in clinical settings. By applying BFR in an arbitrary fashion, the authors neglected years of research and guidance on current best practices for BFR. (4) They suggest that the findings of this study indicate there may be safety concerns with the application of wide rigid cuffs, and that narrow-elastic cuffs would be the safer alternative, but their study wasn’t designed to draw such a conclusion. The only conclusion that can be drawn from this study is that the application of 160 mmHg with 18 cm wide cuffs did something different than walking under the other two conditions. However, it does reinforce the need for researchers and clinicians in the BFR space to consider and control for as many variables as they can when prescribing BFR exercise. This certainly includes consideration of the characteristics of the individual and the exercise parameters needed to provide adequate stress for the desired adaptation.
1. Slysz J, Stultz J, Burr JF. The efficacy of blood flow restricted exercise: A systematic review & meta-analysis. J Sci Med Sport. 2016;19(8):669-675.
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):1849-1859.
3. Centner C, Wiegel P, Gollhofer A, König D. Effects of Blood Flow Restriction Training on Muscular Strength and Hypertrophy in Older Individuals: A Systematic Review and Meta-Analysis. Sports Med. October 2018. doi:10.1007/s40279-018-0994-1
4. Patterson SD, Hughes L, Warmington S, et al. Blood Flow Restriction Exercise Position Stand: Considerations of Methodology, Application, and Safety. Front Physiol. 2019;10:533.
5. Stray-Gundersen S, Wooten S, Tanaka H. Walking With Leg Blood Flow Restriction: Wide-Rigid Cuffs vs. Narrow-Elastic Bands. Front Physiol. 2020;11:568.
6. Loenneke JP, Fahs CA, Rossow LM, et al. Effects of cuff width on arterial occlusion: implications for blood flow restricted exercise. Eur J Appl Physiol. 2012;112(8):2903-2912.
7. Loenneke JP, Fahs CA, Rossow LM, et al. Blood flow restriction pressure recommendations: a tale of two cuffs. Front Physiol. 2013;4:249.
8. Mouser JG, Mattocks KT, Buckner SL, et al. High-pressure blood flow restriction with very low load resistance training results in peripheral vascular adaptations similar to heavy resistance training. Physiol Meas. March 2019. doi:10.1088/1361-6579/ab0d2a
9. Jessee MB, Buckner SL, Dankel SJ, Counts BR, Abe T, Loenneke JP. The Influence of Cuff Width, Sex, and Race on Arterial Occlusion: Implications for Blood Flow Restriction Research. Sports Med. 2016;46(6):913-921.
10. Garber CE, Blissmer B, Deschenes MR, et al. American College of Sports Medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Med Sci Sports Exerc. 2011;43(7):1334-1359.