Blood flow restriction training, also known as BFR, has become popular in recent years. The question is, should you bother with it?

What is Blood Flow Restriction Training?

Blood flow restriction training is a form of training where you place cuffs around your limbs and lift light loads (typically 20 to 40 percent of your 1RM) for many repetitions (1). The purpose of these cuffs is to restrict blood flow from leaving your limbs, which offers some benefits. You should place the cuffs proximally (close to your body’s midline), such as right below your hips and shoulders for the legs and arms, respectively.

It’s worth noting that you shouldn’t restrict the arterial supply of blood to limbs because that is dangerous. Instead, the goal is to limit the venous return of said blood (1). As a result, more blood and metabolic byproducts accumulate inside your muscles.

The idea behind blood flow restriction training is to stimulate a hypertrophic response through light weights. According to some of the literature, BFR allows you to reap the benefits of heavy weight training to failure with much lighter loads (2).

Instead of lifting heavy weights for, say, 6 to 15 reps, BFR allows you to recruit a larger percentage of motor units and induce significant mechanical loading with weights as light as 20 percent of 1RM.

One reason for these effects is the fluid accumulation in the restricted muscles. If you’ve ever done BFR, you’ve likely experienced some of the most intense muscle pumps in your life. By limiting the blood flow out of your muscles, you induce more significant cellular swelling, which appears to stimulate muscle growth (3).

Further, BFR promotes the accumulation of metabolic byproducts (such as lactate and hydrogen ions). Researchers suggest that, aside from causing fatigue, such byproducts play a role in hypertrophic signaling (2).

Why Would Anyone Do Blood Flow Restriction Training?

One simple reason for doing BFR is that you don’t have access to heavy weights. For example, many people train at home, and not everyone has access to heavy dumbbells, barbells, weight plates, and similar. BFR allows you to work hard and exhaust your muscles with light weights.

Another reason for doing blood flow restriction training is if you’re dealing with an injury and you can’t train with heavy weights for the foreseeable future. The modality would allow you to stimulate your muscles without placing significant stress on your joints and connective tissues.

Blood flow restriction training can also be helpful if you’re traveling often and going to hotel gyms that don’t have much equipment.

Isn’t BFR Dangerous? It Seems Dangerous…

Trapping large amounts of blood in your limbs might seem dangerous, but research seems to suggest the opposite (4). A common concern people have regarding BFR is that the training modality might cause blood clots. Fortunately, researchers suggest that the risk of such an event is incredibly small (5).

Other than that, research doesn’t suggest any adverse effects or dangers from practicing BFR within reason.

With that said, I don’t feel comfortable recommending blood flow restriction training, especially online. You have to be careful with the pressure you apply, how long you keep the cuffs on, and more (1). If you do want to try BFR, it never hurts to consult your doctor and train under the supervision of a coach who understands the modality well.

Thank you for reading. Until next week,
Philip

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