Blood Flow Restriction Training and Blood Pressure: What You Need to Know
If someone told you to go do something that would do all of the below:
- Raise your blood pressure
- Increase systemic inflammation in your body
- Spike your blood sugar
- Trigger a sympathetic “fight or flight” response
- Raise your heart rate
What would your response be?
“No thanks.” Right?
Well it turns out, exercise does all of the above.
Yep, the behavior that’s widely understood to contribute to performance, longevity, and more favorable markers of health causes all of that (transiently) - and that’s perfectly fine in most cases!
It’s important to frame that before asking the question of whether or not BFR increases blood pressure, because a transient rise in blood pressure as a response to strenuous activity is not only expected, but necessary!
The more appropriate question is “Does BFR training increase blood pressure beyond what intensity-matched exercise does?”
To that, the answer is likely no.
Let’s unpack that.
Your blood pressure will generally temporarily increase in response to any moderate to intense exercise due to the increase in your heart rate.
What blood flow restriction can do is take a certain activity (resistance training, walking, aerobic capacity training, etc.) and make it more difficult.
Imagine walking on a treadmill for several bouts of 2 minutes at 2 miles per hour (2 minute walk, 60 seconds rest, repeat).
Pretty easy, right?
Now picture doing that same thing but with BFR cuffs around your legs. A bit more difficult.
If you understand what’s happening physiologically in this example, it’s much easier to understand the relationship between blood flow restriction training and blood pressure.
In the example without BFR cuffs, for most people, the intensity (speed) would just be too low to create any metabolic or circulatory burden.
The demand for oxygenated blood in your legs would be easily supplied with only a slight increase in heart rate, and metabolites like lactate wouldn’t have enough opportunity to accumulate (so you’d be unlikely to feel any “burn” in your legs).
On the contrary, with the BFR cuffs, there are two mechanisms by which your blood pressure could increase from this example training bout on the treadmill:
1. Exercise Pressor Reflex
Blood carries oxygen, and with pressurized cuffs around your legs, arterial flow is significantly reduced.
Less blood = less oxygen. Less oxygen available to the muscle tissue can lead to accumulation of metabolites like lactate.
As mentioned in a 2018 meta-analysis on the blood pressure response to BFR, this metabolic environment can increase the activity of the exercise pressor reflex.
The exercise pressor reflex is a natural physiological reflex to exercise that mediates your cardiovascular response.
In other words, when your body detects this lactate accumulation, it responds accordingly to adapt to the task at hand (exercise).
As discussed in a 2008 paper by Mitchell & Smith, the exercise pressor reflex “induces elevations in heart rate and blood pressure predominantly by increasing sympathetic nerve activity.”
We’ve illustrated this process in the image below.
The above image displays the chain of events that lead to exercise-induced blood pressure increases. Remember, these effects occur whether there’s BFR cuffs applied or not if the exercise intensity is sufficient enough!
In the case of walking on a treadmill though, the limited blood flow to your legs could increase the likelihood that that chain of events would occur despite the fact that the exercise intensity is so low.
In other words, BFR just makes the workout more difficult, leading to a similar blood pressure increase as an equally difficult workout without BFR.
2. Relative Decrease in Stroke Volume
To understand this portion, we have to understand the term cardiac output.
Cardiac output is the product of heart rate and stroke volume (heart rate x stroke volume). Stroke volume is the volume of blood pumped out from each heart beat.
Faster heart rate + larger stroke volume = greater cardiac output.
Let’s look at the impact BFR has on cardiac output.
In most cases, blood flow restriction training involves fully occluding venous flow (the blood leaving your limbs headed back towards your heart).
Consequently, stroke volume does not increase as much as it typically would since the BFR bands are preventing venous return.
With stroke volume slightly impeded, heart rate compensatorily increases.
This is well documented in the scientific literature - a 2021 systematic review on the systemic effects of blood flow restriction examined five studies that directly measured blood pressure responses to BFR. Regarding cardiac output, the authors stated:
“When evaluated together, these studies show the application of BFR does not change CO [cardiac output] but does decrease relative SV [stroke volume] amount and increase HR [heart rate] response accordingly to maintain appropriate CO.”
On the topic of blood pressure specifically, the authors noted:
“The studies included in this review suggest BFR using occlusion pressures less than approximately 200 mmHg does not lead to detrimental blood pressure responses in healthy adults. Rather, BFR under these parameters causes similar blood pressure responses as traditional exercise, when prescribed appropriately.”
This is a consistent theme in BFR literature. The added stimulus of blood flow restriction does not appear to elicit a supraphysiological rise in blood pressure in non-hypertensive adults, and any increases in blood pressure observed between BFR and traditional training can generally be attributed to the aforementioned mechanisms.
BFR Training Generally Involves High Rep, Limited Rest Bouts
In addition to the physiological mechanisms, the nature of blood flow restriction training often trends toward more cardiovascularly demanding workouts.
How do you feel after a heavy set of 5 reps on the back squat? Perhaps slightly winded, but overall it's not too taxing from a cardiovascular perspective.
What about a set of 20 - 30 reps?
If you’ve never tried it, you’re in for a treat! The sheer volume and length of time the set takes creates a significant demand for oxygen in the working muscles.
Generally, your heart rate is much higher after a set of 20-30 at 20-30% of your 1RM than a set of 5 closer to your 1RM.
As we know, a hallmark benefit of blood flow restriction training is that it can lead to strength and muscle gain adaptations while training at lighter loads (20 - 30% of your 1RM).
Consequently, much of the research done with BFR involves lighter loads, more reps, and shorter rest periods.
The 30-15-15-15 protocol is a good example: it involves one set of 30 reps, followed by three sets of 15 reps with 30 seconds rest in between sets.
This high rep, limited rest nature of BFR training can theoretically have a greater circulatory demand than traditional resistance training in some cases.
If Intensity is Matched, Blood Pressure Response is Similar
However, in most studies where the control group (traditional resistance training) trains at a high enough intensity (we will define this shortly), blood pressure increases match or even exceed the BFR group’s.
This was observed in a 2012 study by Ozaki et al. where 19 young men were split into two groups:
- High Intensity Training - 3x10 at 75% 1RM with 2-3 minutes rest between sets
- BFR - 30-15-15-15 rep scheme with 30 seconds rest between sets
The subjects performed the above protocol on bench press 3 x per week for 6 weeks.
During the final set of each training session, blood pressure was higher in the traditional resistance training group.
This reinforces the general premise that when exercise intensity is matched, BFR does not appear to elicit any additional increases in blood pressure compared to traditional resistance training in healthy adults.
Ultimately, science is a moving target and there is still much to learn about the science and practice of blood flow restriction training.
We will continue to provide analyses on emerging literature as the relationship between BFR and blood pressure is investigated further over time.
Until then, we hope this article provided clarity on a much-discussed and important safety consideration of BFR training.
Disclaimer: This article and all information on SAGA’s website is for informational or educational purposes only, and does not substitute professional medical advice or consultations with healthcare professionals.