Does blood-flow restriction training work, and who can it help?
Blood-flow restriction training has almost as many applications and names as it has uses.
Some call it occlusion training; others, hypoxic training. Bands, cuffs, and even ACE bandages have been used in attempting to utilize the benefits of the training for a number of desired outcomes.
Yet just about everyone agrees on one point – the practice is gaining popularity due to its effectiveness.
First things first: no matter what name you choose to use, let’s clarify how it works. People, for any number of reasons, may be unable to lift heavier weights or do extensive strength training for a period of time. Whether it’s an injury or another condition, blood-flow restriction training allows the patient to lift lighter weights while receiving benefits similar to people lifting heavier.
“They can gain strength and hypertrophy without having to work at a particularly high intensity,” explained Pieter de Smidt, PT, DPT, Cert. MDT, MTC, who is the president and owner of Reset-Wellness Physical Therapy in Houston, TX. “That makes it ideal for physical therapy patients.”
De Smidt’s explanation is as follows: the accepted standard is that in order to gain strength or hypertrophy, a person must be able to lift weights that are at least 65 percent of the person’s maximum capacity for that exercise. For example, if you can lift 100 pounds, you must lift at least 65 pounds in order to see tangible benefits in added strength.
Of course, for people coming off of recent injury or surgery, this is an impossible task. It becomes challenging for the physical therapist to allow these patients to strengthen themselves because of the reduced capacity for exercise and lifting. “I can’t make you work hard enough for the body to adapt,” explained de Smidt.
With blood-flow restriction training (BFRT), however, that same patient who is unable to lift 65 pounds while recovering or while injured can suddenly see benefits while lifting only, say, 20-25 pounds.
How? Say you want to work your upper body. You wrap a pressure cuff or similar restrictive instrument around the upper portion of that limb, reducing the ability of blood to flow out of the working muscle. When properly performing blood-flow restriction training, blood is able to enter the muscle via arterial flow, but the veins are restricted so that blood is partially prevented from leaving the working muscle.
“That’s the ideal scenario for repairing the tissues,” de Smidt explained. “But by lifting lighter weights, you’re not providing any mechanical stress or doing mechanical damage to your muscles. Everything you do goes toward growth.
It’s a great way to gain that strength safely, while slowly progressing toward your ability to lift those weights normally. It’s a temporary solution – you don’t need to be doing it forever, just until you’ve safely regained strength and the patient is able to lift heavier items again.”
De Smidt was originally attracted to blood-flow restriction training not only by its ability to create hypertrophy, but by the potential for utilizing the training for prevention in a passive state. “If I restrict your blood flow without anything else,” he explained, “while you’re, say, in a cast, you will not lose your muscle mass or strength if you do this training during immobilization. Otherwise, strength loss and atrophy can occur very quickly.”
Post-injury, post-surgical, post-immobilization – they’re all strong indicators for the potential benefits of blood-flow restriction training. “It works for anyone who has a reason why they’re unable to perform typical, high-intensity exercises can benefit,” said de Smidt. “But it can also be used in your athletic population.”
De Smidt outlined a pair of uses for BFRT in athletes – in-season training, when coaches and trainers are leery of players hitting the weights too hard, or use it as the finishing touch at the end of the workout to maximize the benefit of strength training. “You can reduce the mechanical stress component,” de Smidth said of the first example.
De Smidt cautioned against using the method with post-surgical patients before consulting with the surgeon. It’s also important to account for any cardiovascular restrictions, such as hypertension, before proceeding with blood-flow restriction training. PTs should avoid utilizing BFRT in areas with open wounds or impacted by lymphedema. ANy area with clotting risks or limbs with a dialysis port should also be avoided.
Years ago, patients would undergo surgery for vascular necrosis of the hip. These patients were too young for a total hip replacement, so the chosen procedure would require six months non-weight bearing, It’s easy to imagine the atrophy and loss of strength that would take place over that time.
“Initially, we started those patients on a passive protocol, followed by an aerobic protocol, and finally strength training,” de Smidt recalled. “Using BFRT, we saw significant differences in the strength loss as opposed to in the past.
“That’s how I got into this – they were immobilized, they weren’t allowed to do many exercises because of that initial fragility. This allowed us, for a few weeks, to get ahead of the atrophy. Slowly, we made the patients more and more active, and it was nice to see how BFRT helped in that process.”
PTs, OTs, certified athletic trainers, and personal trainers can all benefit by utilizing BFRT similarly with their patient populations. “As long as [the professionals] know how to use it, it can be very effective.”
De Smidt cautioned that each session shouldn’t exceed 10-20 minutes, and that this strategy should not be used as a primary strength-building approach. “If you’re healthy, and able, the research shows you should be lifting heavier weights to gain strength and hypertrophy,” he urged. “Once, twice a week in a healthy person, this can provide a different kind of stimulus because you fatigue much more quickly. You can use it as the finishing touch to a regular workout.”
BFRT is great for strength training, hypertrophy, aerobic endurance – it can be used to increase a patient’s VO2 max in a short amount of time – and can be performed actively or passively. But by using it at the beginning of a session, de Smidt says you can reduce the patient’s pain, expanding their capacity for exercise throughout the session. After injury, the patient can start day one, while post-surgical patients tend to wait 1-2 weeks before starting through a slow progression.
Lastly, a few safety precautions: de Smidt says the gold standard is usage of a Doppler to determine lymph occlusion pressure. “Say, at 200, we have no more pulse shown, we work at about 50 percent of that. We don’t want maximum occlusion –the key is doing this safely to maximize its potential.
With several decades of research behind the method, de Smidt says BFRT should likely be used more liberally within the clinical setting, but some practitioners have concerns about safety…
If you would like to learn more from de Smidt himself, sign up for one of his seminars by following this link.