Does Blood Flow Restriction Training Benefit Muscles Proximal to the Cuff?

7 min read. Posted in Exercise Prescription
Written by Zenia Wood info

Substantial evidence supports the numerous benefits of Blood Flow Restriction Training (BFRT) on muscles distal to the cuff placement, but this begs the follow up question:

“Are there any benefits of using BFRT for areas proximal to the cuff, like the shoulders and glutes?”

While BFRT has been around since the 1960s when it was known as KAATSU training in Japan, it’s popularity in the literature has only begun to make headway in the last decade (1). As a result, the effects of BFRT on areas proximal to the cuff as well as systemically are still widely unknown.

Before we explore this topic, first let’s recap what BFRT is, and its known benefits distal to the cuff.

 

What is BFRT?

The occlusion of blood flow (both arterial and venous restriction) with a tourniquet during exercise with the intention to improve muscle growth in both size and strength, while simultaneously allowing significantly lighter loads to be lifted (2,3).

While the mechanism of BFRT is not completely understood, the general consensus is that BFRT causes hypertrophy through a combination of muscle cell swelling and metabolic stress (4).

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What do we know about the impacts of BFRT distal to the cuff?

  • BFRT has the ability to slow and can even negate the negative impacts of muscle atrophy (5)
  • BFRT increases metabolic stress without the same increase in mechanical tension from the lighter loads which results in reduced joint stressors (6).
  • Low-load BFRT provides similar muscular hypertrophy to heavy loads without BFRT (6).
  • There is conflicting evidence as to whether low-load BFRT increases muscular strength to the same degree as heavy resistance training (7).

Initially, BFRT was popular among those looking to purely increase muscle strength and size. However, due to the growing evidence around its widespread uses, BFRT has sparked interest in the rehab community as a unique and attractive injury rehabilitation tool as well.

 

Are there any benefits to BFRT in muscles proximal to the cuff?

Upper Extremities

Interestingly, most studies found positive effects in support of BFRT over non-restricted training (7,8,9). However, Yasuda and colleagues (2011) found a non-significant increase in chest muscle hypertrophy. They compared bench press using BFRT at 30% 1RM with non-BFRT at 70% loads. The lean muscle development with BFRT was nearly 50% less than regular heavy resistance training. The researchers proposed that the large inter-individual muscle activation variability was the cause of this isolated result (7).

The general consensus among the literature is that BFRT, even at cuff pressures of just 50%, produce greater increases across a range of outcomes. These include isometric strength, hypertrophy (both distal and proximal to the cuff) and reduced repetitions to failure (8,9).

Greater increases in EMG of both distal and proximal muscles have been observed during BFRT in some studies (8) but not in others (10). The theory for those in support of increased EMG is that as the distal muscles approach failure faster, the requirement of proximal synergistic muscles increases. This leads to a subsequent increase in fast twitch fiber recruitment of the proximal musculature, resulting in higher recruitment levels overall. This mechanism is known to promote both hypertrophy and strength improvements (7).

Meanwhile Brumitt, Hutchison and Kang (2020) observed similar increases in both strength and tendon thickness of the rotator cuff musculature for upper limb occlusion, however noted no difference in whether BFRT was or was not used when exercising to failure* (11).

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Lower Extremities

Unfortunately, very few studies using lower limb occlusion focus on exercises targeting proximal muscles (e.g. gluteals), however the preliminary research results are in favour of BFRT.

There was only one high quality study found of this nature. It showed an increase in gluteal muscle cross sectional area (MCSA) of 4.4% following 12 weeks of bi-weekly leg extensions and leg press* with BFRT when compared to without BFRT (12).

Conversely, slow walking with BFRT for 20 minutes, 5 days per week for 6 weeks in older adults only increased distal (quadricep) but not proximal (gluteal) MCSA. It was suggested that gluteal loading was insufficient for changes in this region. (13)

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What can we conclude from this?

The large majority of studies on proximal benefits of BFRT reported positive effects on muscle mass, with most also reporting improved strength. Additional benefits included reduced repetitions to fatigue which practically means less time spent training when lighter loads are used (8,9). With respect to the upper limbs, BFRT also demonstrates its beneficial effect at relatively low occlusion pressures (7).

All studies with proximal muscle benefits also reported distal improvements to the same, if not a greater extent. This aligns with the theory by Abe and colleagues (2005) that the minimum exercise intensity for muscle hypertrophy could be as little as 10% of maximal voluntary isometric contraction (MVIC) for muscles distal to the cuff, and approximately 20% of MVIC for those proximal (14)

We must also be aware that volume-matched exercise in the absence of BFRT does not elicit beneficial muscle adaptations. Low-load BFRT (20-30% RM) does however, provide a greater increase in strength and size in both proximal and distal muscles of the upper extremity when compared to low-load without BFRT when both are trained to failure (15). Similar results were found when performing exercise at a 7-8 rating of perceived exertion (RPE) as well (9).

 

What about the systemic benefits of BFRT?

Systemic benefits of BFRT have also been suggested to impact proximal musculature positively. Increased muscle activation in the trunk was believed to occur as a compensation strategy for reduced force output (16), supporting this hypothesis.

Anabolic hormonal levels, such as growth hormone and testosterone, have been proven to acutely rise post BFRT (14) and other systemic growth factors such as muscle cell swelling that are obvious in distal muscles, have now shown to be present to a lesser degree in proximal muscles as well during BFRT (7).

Even grip strength in the non-BFRT extremity of single arm exercise showed a significant increase in grip strength when compared with regular resistance training, indicating a potential systemic effect (9).

While all of these results appear promising, the long term effects of BFRT are still yet to be uncovered.

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Implications for rehab

While we know strength and size are pivotal in their support of injury prevention and management, BFRT as a method of pain reduction has not been studied. There is one paper titled “Blood Flow Restriction Training in Patients With Shoulder Pain” which may provide some preliminary insights, however these results are yet to be released (17).

 

Take-home messages

While there is some evidence of little to no benefit, the majority of the research is promising in the support of BFRT for muscles proximal to cuff placement. We know that low-load BFRT leads to an acute increase in size and often strength in muscles both distal and proximal to the tourniquet (14). Additionally, when using the same loads and not working to failure BFRT outperforms non-BFRT (11).

Low-load BFRT (20-30% RM), especially for proximal muscles, is not shown to be greater than heavy resistance training (60-90% RM) without BFRT. In saying this, it is not known whether there are additional benefits to utilising BFRT in conjunction with heavy resistance training or for rehabilitative purposes.

If you found this useful and want to learn more about the practical applications of BFRT, then check out this great Masterclass by Dr Luke Hughes.

*Note: Most studies reviewed in this article used bi-weekly training with 1-4 exercises involving the occluded limb(s). Study durations lasted between 6-12 weeks, with all subjects performing 4 sets of 30,15,15,15 repetitions or repetitions of 30,15,15,failure.

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