Under Pressure: What's New on BFR & Compression Gear? Of Swollen Legs, Arterial Stiffness & Improved Bone Health

Is it all about pressure? Compression stocking and BFR cuffs revisited.
You will remember that I've covered the use of #BFR, i.e. blood-flow restriction in several articles over the past years. The number of posts on #compression stockings, on the other hand, is limited with only one dealing with the acute anti-heavy-leg effect of 'oma's socks' in the evening.

Today's special will address both, the latest research in everything tight... ;-) Ok, before the ambiguity gets out of hand, let's check out some of the latest studies:
BFR and Hypoxia Training are different from training w/ compression garments

BFR, Cortisol & GH Responses

BFR - Where are we now?

BFR as Add-On to Classic Lifts

BFR for Injured Athletes

BFR B4 Workouts = WIN!?

BFR + Cardio = GainZ?
  • In healthy young women, compression stockings may have acute beneficial effects on lower leg swelling and muscle stiffness (Sugahara 2018): While previous trials have often yielded ambiguous results, the latest paper by scientists from Japan Women's University claims to "suggest that even for a short period of application, compression stockings have some positive effects against lower leg swelling" (ibid)... but there's more than the problem with the absence of a real control group of which the scientists say that "it is highly unlikely that the lack of control condition seriously affects the significance of our findings" (ibid) and claim:
    Prolonged standing may be as problematic as sitting | more.
    "Rather, the study design did not take into account the preventive effect of wearing compression stockings on leg fluid accumulation that could be induced by even a 20–30 min of sitting, although this was not the primary concern of this study" (Sugahara 2018).
    If that was actually the case, wearing some 'sexy' compression stockings at work may help you ameliorate the circulatory problems triggered by prolonged sitting (and as recently demonstrated even standing).

    Before we make further assumptions, though, let's briefly see what those "acute benefits" the Japanese researchers observed actually were.

    Figure 1: Volumes of foot (a), calf (b) and total lower leg (c) measured before and after an application of compression stockings. In each panel, small grey circles = individual data, whereas a large black circle = the group mean. The right panel shows the percent change expressed as mean and SD (n = 20 | Sugahara 2018).
    As previously pointed out, the study involved healthy young women. The N=20 ladies in the age of 18–23 years wore below‐knee graduated compression stockings after returning home in the evening. They were not allowed to lie down, but rested in a seated position for 30 min.

    Before and after the application of stockings, maximum calf, volume, circumference, extracellular water resistance (RECW) and muscle stiffness of the right lower leg were determined by tape measure, water displacement volumetry, segmental bioelectrical impedance spectroscopy and ultrasound shear‐wave elastography, respectively.

    Unlike the foot volume, the calf volume, and the total lower leg volume, as well as the muscular stiffness of the medial gastrocnemius muscle which only tended to decrease, the maximum calf circumference (vs. volume) decreased significantly (but probably not visibly | -0.35 cm) after the application of the stockings.

    In conjunction with the reciprocal of RECW (an index of extracellular fluid volume), it thus seems likely that compression stockings can a least partially reverse the accumulation of fluids in the legs that will occur not just in heart-diseased subjects, but also in healthy individuals.

    Obviously, the study at hand cannot provide hard evidence (=real-world outcomes) in terms of the downstream effects on our CVD risk. So, does that even matter?

    In view of the small (-1.0% or 0.35cm) reduction in calf circumference, the absence of significant effects on the total lower leg volume, and the lack of correlation between changes in the different parameters the scientists measured, the authors themselves cannot exclude that the stockings simply "pressed" the lower legs into a new shape:
    "More specifically, a brief application of compression stockings on swollen legs may result in greater compression pressure on more swollen part of the leg, affecting the fluid distribution within the lower leg before accelerating the fluid shift from the lower leg to the thigh. This possibility is particularly relevant to our experimental protocol, e.g. participants wore below‐knee stockings and rested in a seated position during the 30‐min application" (Sugahara 2018).
    If that was actually the case, though, we must, unfortunately, assume that using the sexy "compression lingerie" at the end of a workday for only 30 minutes will probably do very little for your risk for common circulatory disorders or other CVD risk factors. What it may help with, however, are tightly wound calf-muscles in the evening... and, we shouldn't forget that wearing them preventively at work may be the more relevant intervention, anyway.
This image from my article about the post-set application of BFR (learn more) shows how reliable BFR cuffs can look like - fundamentally different from the blood pressure cuffs at the doctor's office. You can learn more about BFR in the SuppVersity archives - please klick on "older articles" at the bottom to dig deeper into the archives.
BFR cuffs - The broader the better? Ok, that was not exactly the research question Mouser et al. (2018) tried to answer, but, I guess, you'll still get the idea. In their study, the scientists from the The University of Mississippi tested the effects of cuffs with a width of 10 and 12 cm, respectively, in 17 male and 14 female subjects on two separate occasions using ultrasound measures of blood flow, mean blood velocity, peak blood velocity and artery diameter from the posterior tibial artery at rest and during the application of 10% increments of the aortic pressure.

The results were quite unequivocal: "As long as relative pressures are applied, cuff width appears to have little to no effect on the blood flow stimulus during blood flow restriction at rest" (Mouser 2018). That doesn't mean, though, that you can achieve the same effect with parcel strings or the small and fragile cuffs docs use to get your blood for the lab.

Why 10 and 12 cm? I guess that's what you're asking yourself now. Well, it's worth mentioning that the scientists have already published a paper on the effects of cuff width in 2012 -  a paper with an IMHO practically more relevant comparison of 13.5cm and 5cm cuffs (Loenecke 2012). And while 5cm is still much wider than the previously mentioned cuffs at the doctor's office the scientists did find a significant difference due to the 8.5 cm difference - namely that broader cuffs can achieve the same reduction of arterial blood flow at much lower inflation pressures... for further details on choosing the optimal cuff width and material, pressure, arm circumference, sex, etc, I suggest you read Loenecke's free 2013 paper in Frontiers in Physiology and a 2016 follow-up study that was published in Sports Medicine (Jessee 2016).
  • Small arteries stay stiff for a longer period following vibration exercises in combination with  blood flow restriction (Karabulut 2018): Aortic stiffness is, according to a 2012 paper in the Journal of Cardiovascular Translational Research (Tomiyama 2012), a potential trigger and perpetuator of (pre-)hypertension. What is particularly nasty is that the increased blood pressure will only worsen arterial stiffness and the consequent vicous cycle can lead you from
    'pre- to post-hypertension' (=death due to pressure-induced CVD).

    In view of the association of arterial stiffness with the onset and progression of hypertension, the study at hand sounds like bad news for you or your clients who use similar blood flow restricted vibration training regimen.

    The latter, i.e. using BFR as an adjunct to vibration training was exactly what the eight male subjects did in the study at hand: They performed static upper body (UB) and lower body (LB) exercises on a vibration platform with and without BFR. During the BFR sessions, BFR cuffs were placed on the arms or legs and inflated to a target pressure. Exercises consisted of eight 45‐s sets for UB, and ten 1‐min sets for LB. Arterial elasticity and hemodynamic variables were assessed before, at 10 min and 40 min postexercise. Repeated measures ANOVA was used to test the mean differences in related variables.
    Figure 2: Changes in large arterial elasticity values following (a) lower and (b) upper body static exercises. Values reported as Mean ± SE (Karabulut 2018)
    As previously hinted at,  the scientists found a significant difference between the BFR versus no‐BFR trials for the subjects' small arterial elasticity (P<0·05). As Figure 2 goes to show you, the result differed slightly for lower and upper body but a significant reduction in small artery elasticity was observed in both body parts.
Kaatsu, the Japanese version of BFR, with a rich tradition has an excellent safety profile (Nakajima 2018).
What about the general safety of #BFR? As Nakajima et al. point out in their 2006 review, blood flow restriction in form of the Japanese KAATSU training doesn't just have a long tradition but is still applied to all generations - from very young (<20 years old) to very old (>80 years old).

That alone does yet not warrant the conclusion that it's safe and side-effect free. Accordingly, the scientists questioned the "KAATSU leaders" or instructors in a total of 105 out of 195 facilities where KAATSU training has been adopted.

Based on survey results, 12,642 persons had received KAATSU training (male 45.4%, female 54.6%). Interestingly enough, the most popular purpose of KAATSU training in the study was to strengthen muscle in athletes and to promote the health of subjects, including the elderly. Approximately 80% of the facilities are satisfied with the results of KAATSU training with only small numbers of complications reported.

The incidence of side effects was as follows; venous thrombus (0.055%), pulmonary embolism (0.008%) and rhabdomyolysis (0.008%) - see Figure. "These results indicate that the KAATSU training is a safe and promising method for training athletes and healthy persons, and can also be applied to persons with various physical conditions," Nakajima et al. (2006) conclude.
  • The obvious question now is: How bad is the impaired restoration of the blood flow in the small arteries? And the answer will hopefully calm you down: Probably not too bad. After all, the systemic effects (not shown in Figure 2) were not affected by BFR and, after plummeting at the 10-minute mark, returned to normal at the 40-minute mark in both the BFR and control trial - a delayed recovery you can see in Figure 2 for the small arteries was absent.

    Moreover, we cannot exclude the possible occurrence of an augmentation of the training effects and corresponding (positive) adaptations of the vasculature due to the increased physical demand of combined training (the scientists observed a significantly higher heart rate in the BFR trial. Needless to say that this does not apply for pre-existing vascular disease. They are probably better off if the stay away from BFR and/or perform it only under medical supervision.
  • Logical, but also true? Intense exercise, especially weight-bearing exercise, has been shown to be a potent bone builder. BFR has been shown to augment the adaptive response to light(er) exercise. Does this mean BFR training can also build bone? Scientists from the Federal University of Paraíba tried to figure that out in their recent review of the literature (Bittar 2018) - albeit with moderate success.

    Bittar et al. searched for studies that analyzed the effect of low‐intensity (LI) exercises with blood flow restriction (BFR) on bone metabolism and compared it to the proven benefits of high‐intensity (HI) exercises without BFR. Two researchers, independently and blindly, selected the studies based on established inclusion and exclusion criteria.

    There are all sorts of different BFR regimen. In this study from the SuppVersity archives, the cuffs were applied before (3x5 minutes), not during the exercise and still: the increase in the putative marker of muscle damage, creatine kinase, was significantly ameliorated.
    While the initial electronic and manual searches had located 170 articles published in English, only four studies survived the screening process. The good news is that they seem to support the initially proposed rationale "that BFR training increases the expression of bone formation markers (e.g. bone‐specific alkaline phosphatase) and decreases bone resorption markers (e.g. the amino‐terminal telopeptides of type I collagen)" not just in response to strength training, but also "after both aerobic [...] exercise across several populations". Still, in the absence of methodological standardization of the samples, exercise type, intervention frequency or duration - more research will be necessary to quantify the effect size in a meta-analysis.
Meta-analysis suggests: Gymgoers may benefit most from wearing compression garments.
Bottom line: While the research investigating the health and performance effects of #compressionGarments and #stockings is still more-or-less in its infancy, the number of studies which probe the efficacy and safety of different types of #bloodFlowRestriction has increased rapidly over the past decade.

In that, one has to be careful, though, to avoid getting too excited about the pro-anabolic effects of blood flow restricted (low intensity) training and/or getting too anxious over the previously discussed transient ill effects on arterial stiffness.

Needless to say that the same applies to the performance and or health effects compression garments, too. For them, the latest meta-analysis concludes that "LLCGs [lower-limb compression garments is] not associated with improved performance in VJ [vertical jump], VO2max, VO2submax, Lactate, or RPE during high-intensity exercise" (da Silva 2018). This result clearly relativizes the measured, bu often small benefits in individual studies and reminds me to refer you to a more comprehensive review I blogged about last year - a review that seems to suggests that gymrats not endurance athletes, who made up the majority of the subjects in the studies reviewed by da Silva et al., may benefit most from the strategically timed use of compression garments | Comment!
  • Bittar, S. T., Pfeiffer, P. S., Santos, H. H. and Cirilo‐Sousa, M. S. "Effects of blood flow restriction exercises on bone metabolism: a systematic review." Clin Physiol Funct Imaging, 38 (2018): 930-935. doi:10.1111/cpf.12512
  • da Silva, César Augusto, et al. "Association of Lower Limb Compression Garments During High-Intensity Exercise with Performance and Physiological Responses: A Systematic Review and Meta-analysis." Sports Medicine (2018): 1-15.
  • Jessee, Matthew B., et al. "The influence of cuff width, sex, and race on arterial occlusion: implications for blood flow restriction research." Sports Medicine 46.6 (2016): 913-921.
  • Loenneke, Jeremy P., et al. "Effects of cuff width on arterial occlusion: implications for blood flow restricted exercise." European journal of applied physiology 112.8 (2012): 2903-2912.
  • Loenneke, Jeremy P., et al. "Blood flow restriction pressure recommendations: a tale of two cuffs." Frontiers in physiology 4 (2013): 249.
  • Mouser, J. G., Dankel, S. J., Mattocks, K. T., Jessee, M. B., Buckner, S. L., Abe, T. and Loenneke, J. P. "Blood flow restriction and cuff width: effect on blood flow in the legs." Clin Physiol Funct Imaging, 38 (2018): 944-948. doi:10.1111/cpf.12504
  • Reed, Katharine E., et al. "The effects of lower-body compression garments on walking performance and perceived exertion in adults with CVD risk factors." Journal of science and medicine in sport 20.4 (2017): 386-390.
  • Sugahara, I. , Doi, M. , Nakayama, R. and Sasaki, K. "Acute effect of wearing compression stockings on lower leg swelling and muscle stiffness in healthy young women." Clin Physiol Funct Imaging, 38 (2018): 1046-1053. doi:10.1111/cpf.12527
  • Tomiyama, Hirofumi, and Akira Yamashina. "Arterial stiffness in prehypertension: a possible vicious cycle." Journal of cardiovascular translational research 5.3 (2012): 280-286.
  • Vlachopoulos, Charalambos, Konstantinos Aznaouridis, and Christodoulos Stefanadis. "Prediction of cardiovascular events and all-cause mortality with arterial stiffness: a systematic review and meta-analysis." Journal of the American College of Cardiology 55.13 (2010): 1318-1327.
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