Should We Adjust Cuff Pressure Over the Course of an Intervention? Part 1

There are some things that are well-established in the scientific literature, like how smoking is bad for you, exercising is good for you, and N’SYNC is better than Backstreet Boys in every possible way.  Still, other things are not so well-established in the scientific literature, like the nuances of pain, how to prevent injury, and why my father chooses to drive to a gas station that is 20 minutes out of the way to save 9 cents per gallon.  When there are questions, there are researchers we want answers.  

In their 2021 paper titled, “Blood Flow Restriction Training: To Adjust or Not Adjust the Cuff Pressure Over an Intervention Period?,”  Cerqueira and colleagues set out to answer an important question about cuff pressure during blood flow restriction training.  It is known that BFR pressure (BFRP) needs to be individualized and adequate to partially limit arterial blood (Patterson et al., 2019), however there are no clear recommendations for BFRP prescription (Clarkson et al., 2020) and no specific recommendation of whether BFRP should be adjusted.

Neuromuscular adaptations induced by BFR are widely studied, however cardiovascular changes throughout training intervention with BFR and their possible relationship with BFRP are less understood. These cardiovascular changes include central and peripheral hemodynamics, ischemic reperfusion-> sheer stress, and the exercise pressor reflex, which is the exaggerated cardiovascular response to exercise, specifically the exercise pressor reflex (EPR).  As quoted from one of my previous blogs titled, The Exercise Pressor Reflex: Should We Be Concerned? Part 1, “The EPR has two functional components: the muscle metaboreflex (reduction oxygen/blood flow to muscle tissue and the accumulation of metabolites) and the muscle mechanoreflex (mechanical distortion of group III afferents due to tissue compression during skeletal muscle contraction (Kaufman, 1984) in direct proportion to the intensity of the exercise (Adreani, 1997, Kaufman, 1983,  (Boushe, 2010, McCloskey, 1972, Mitchell, 1983).  Both components act to increase sympathetic nerve activation (SNA) during exercise.  

Let’s dig a bit deeper into the cardiovascular adaptations associated with BFR exercise.  Cerqueira and colleagues highlight the many inconsistencies across the literature: 

• Adjust pressure or not? Why?

• Cuff pressure

• Cuff width

• Time under BFR

• Training protocol: modality, sets, reps, frequency, overall volume, # of weeks (duration)

Structural adaptations in the vascular tree can occur due to metabolic changes elicited by hypoxia, mechanical stretch, shear stress, and increased growth factors, such as vascular endothelial growth factor (VEGF) (Hudlicka and Brown, 2009).  Furthermore, the reactive hyperemia occurring after BFR can stimulate capillarization (Evans et al., 2010) as well as improve arterial compliance, stiffness, and arterial diameter (Ozaki et al., 2011; Hunt et al., 2013).  Keep in mind that the accumulation of metabolites (metabolic stress) and the exercise pressor reflex increase heart rate, blood pressure, and cardiac sympathetic modulation (Junior et al., 2019; Cristina-Oliveira et al., 2020).  

Adaptations in resting HR and BP following BFR training are inconsistent across the literature, with 35% of the studies adjusting cuff pressure during treatment.  There were also inconsistencies in cuff width, amount of pressure used, and justifications as to why.  Although literature is inconsistent, there is evidence to support that BFR training may reduce HR and BP and increase HR variability and arterial diameter.

Had enough yet?  Or are ya thirsty for more?  Stay tuned for Part 2 of this beast of a blog where I will explain the results, conclusions, and practical applications if this information.  See you then!

References

Adreani CM, Hill JM, Kaufman MP. Responses of group III and IV muscle afferents to dynamic exercise. J Appl Physiol 82: 1811–1817, 1997.

Clarkson, M. J., May, A. K., and Warmington, S. A. (2020). Is there rationale for the cuff pressures prescribed for blood flow restriction exercise? a systematic review. Scand. J. Med. Sci. Sports 30, 1318–1336. doi: 10.1111/sms.13676

Cristina-Oliveira, M., Meireles, K., Spranger, M. D., O’Leary, D. S., Roschel, H., and Peçanha, T. (2020). Clinical safety of blood flow-restricted training? a comprehensive review of altered muscle metaboreflex in cardiovascular disease during ischemic exercise. Am. J. Physiology-Heart Circulatory Physiol. 318, H90–H109. doi: 10.1152/ajpheart.00468.2019

Evans, C., Vance, S., and Brown, M. (2010). Short-term resistance training with blood flow restriction enhances microvascular filtration capacity of human calf muscles. J. Sports Sci. 28, 999–1007. doi: 10.1080/02640414.2010.485647 

Hudlicka, O., and Brown, M. D. (2009). Adaptation of skeletal muscle microvasculature to increased or decreased blood flow: role of shear stress, nitric oxide and vascular endothelial growth factor. J. Vasc. Res. 46, 504–512. doi: 10.1159/000226127 

Hughes, L., & Patterson, S. D. (2020). The effect of blood flow restriction exercise on exercise-induced hypoalgesia and endogenous opioid and endocannabinoid mechanisms of pain modulation. Journal of applied physiology (Bethesda, Md. : 1985), 128(4), 914–924. https://doi.org/10.1152/japplphysiol.00768.2019

Hunt, J. E. A., Galea, D., Tufft, G., Bunce, D., and Ferguson, R. A. (2013). Time course of regional vascular adaptations to low load resistance training with blood flow restriction. J. Appl. Physiol. 115, 403–411. doi: 10.1152/japplphysiol. 00040.2013 

Junior, A. F., Schamne, J. C., Perandini, L. A. B., Chimin, P., and Okuno, N. M. (2019). Effects of walking training with restricted blood flow on HR and HRV Kinetics and HRV recovery. Int. J. Sports Med. 40, 585–591. doi: 10.1055/a- 0942- 7479 

Kaufman MP, Longhurst JC, Rybicki KJ, Wallach JH, Mitchell JH. Effects of static muscular contraction on impulse activity of groups III and IV afferents in cats. J Appl Physiol 55: 105–112, 1983.

McCloskey DL, Mitchell JH. Reflex cardiovascular and respiratory responses originating exercising muscle. J Physiol 224: 173–186, 1972. 

Mitchell JH, Kaufman MP, Iwamoto GA. The exercise pressor re- flex—its cardiovascular effects, afferent mechanisms, and central path- ways. Annu Rev Physiol 45: 229–242, 1983.

Ozaki, H., Miyachi, M., Nakajima, T., and Abe, T. (2011). Effects of 10 weeks walk training with leg blood flow reduction on carotid arterial compliance and muscle size in the elderly adults. Angiology 62, 81–86. doi: 10.1177/  0003319710375942  

Patterson, S. D., Hughes, L., Warmington, S., Burr, J., Scott, B. R., Owens, J., et al. (2019). Blood flow restriction exercise: considerations of methodology. application, and safety. Front. Physiol. 10:533. doi: 10.3389/fphys.2019.00533 

Sundblad, P., Kölegård, R., Rullman, E., and Gustafsson, T. (2018). Effects of  training with flow restriction on the exercise pressor reflex. Eur. J. Appl. Physiol. 118, 1903–1909. doi: 10.1007/s00421-018-3911-3912

****Remember, the decision to use BFR, or any treatment for that matter, should be based on the pillars of evidence-based practice.

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