Whether you’re a newbie to the gym or a seasoned pro that’s been around the block, the sports science around us is constantly evolving. New methods of training and techniques seem to pop up around every corner. I first saw what I learned was BFR training on social media when I saw a friend working out at their gym with straps positioned around their upper leg. Of course, I had to google it. Turns out, BFR training was a method of training that’s been studied extensively and is shown to be helpful for many aspects of training, including injury recovery!
BFR training, as the name suggests, restricts blood flow to the working muscles or muscle groups during a workout. It is similar to (but different from) KAATSU training which originated in Japan in 1966 to fight muscle atrophy. BFR is specifically useful for people with chronic illnesses or weaknesses and even older adults who may be unable to perform high-load resistance exercises. BFR helps stimulate the muscles while keeping the workload minimal and doable.
Intrigued, we researched BFR training, its uses, benefits, and disadvantages, and how it is linked to injury recovery. So, read on and learn how blood flow restriction promotes greater muscle hypertrophy without overloading your muscles!
Blood Flow Restriction Training
Blood flow restriction to the muscle is achieved using a tourniquet of some sort. It could be a strap, a rubber band, or a piece of cloth. Blood pressure cuffs are used in the scientific studies linked in this article. The tourniquet is worn around the top of the muscle (e.g., the upper part of your biceps) to limit blood flow. This technique is not meant to completely isolate the muscle from receiving its blood supply but instead limit the flow of blood exiting the muscle by constricting the veins. Keeping blood in the muscles will stimulate growth and increase the size of the muscle cells. This is known as hypertrophy.
The Science Behind BFR Training
So how exactly does holding blood in your muscles benefit you? There were a number of studies conducted that have established a few benefits of BFR training, which we will take a look at below!
1. Hormonal Responses and Hypertrophy
As you may know, hormones are the chemical messengers needed to bring about changes in our bodies. One of the most studied effects of BFR training is the production of hormones that stimulate muscle growth. Simply put, when the blood is kept from exiting the muscle, clearing metabolic by-products like lactic acid, adenosine, and other ions is slowed, which triggers the GH response in the body.
In addition to the build-up of by-products (namely, lactic acid), hypoxia or low oxygen due to reduced blood circulation also promotes various chemical changes in and around muscles. These two factors result in an acidic pH which brings about hormonal responses.
The primary hormones that are increased due to the concentration of acidic content are growth hormones, IGF-1 (peptide hormone), and testosterone or anabolic hormones. In general, these hormones turn on the growth genes that result in hypertrophy!
Of course, all these things occur as a result of regular training and exercise as well. The critical part of what makes BFR so great is that, compared to regular exercise, BFR causes an increased number of these metabolites in your muscles. The muscle will be stimulated enough to induce hypertrophy even at a lower weight load. In fact, some studies found that BFR training produced even greater muscle hypertrophy than regular exercise!
And, when it comes to injury recovery or muscle recovery following a disease, BFR gives a tremendous advantage. More hormonal signaling can be achieved by using a minimal load and higher rep range, leading to greater muscle growth and recovery. Since people with injuries may be unable to lift too heavy, this allows them to have safer and more substantial results while fighting muscular atrophy.
2. Intracellular signaling and Hypertrophy
Intracellular signaling, as it relates to muscular hypertrophy, refers to the molecules released or synthesized due to muscle stimulation. These molecules activate or ramp up certain pathways, especially the muscle protein-building pathways. This process is similar to the hormonal responses we discussed above!
The heightened concentration of post-exercise metabolites (e.g. lactate, hydrogen ions, and phosphate) are responsible for increased intracellular signaling activity. BFR training has been seen to increase the anabolic signaling mTOR pathways 3 hours post-BFR exercise, which is directly responsible for muscle growth
These increased intracellular signaling pathways are equal to heavy load resistance training. So, if you can’t curl 100 pounds, with BFR you will be able to achieve similar hypertrophy with 20 pounds!
3. Muscle fiber type recruiting (fast vs slow)
A ton of research has been devoted to understanding which type of muscle fibers are recruited as a result of BFR training. Our bodies house two types of muscle fibers, the fast (white) and slow (red) muscle fibers. The fast muscle fibers are used for powerful, jerky movements (e.g. a bicep curl, bench press, or squat). They reach their point of fatigue early and make up most of the resistance training muscle hypertrophy. Fast muscle fibers show more hypertrophy relative to the slow muscle fibers. Slow fibers, on the other hand, are endurance muscle fibers that stay contracted for long periods of time without getting fatigued. These include your erector spinae (muscle erecting the spine) and calf muscles, enabling you to walk miles before fatiguing. Evidence from various research shows that BFR training incorporates fast (white) muscle fibers.
Blood Flow Restriction Training Applications
Since the 1960s, BFR has been utilized by many trainers to increase muscle size, strength, and endurance. Some common uses of BFR training include:
- For hospitalized patients - hospitalized patients feel constantly weak, especially patients combating cancer. Adding in the muscle atrophy due to chemotherapy, they generally feel very low-energy and down. BFR, along with hormonal supplementation, has shown promising results in muscle retention in such patients.
- Muscle and injury recovery - the accumulation of metabolites in muscles via BFR ramps the muscle growth signals, leading to a faster recovery. In this regard, it outweighs the benefits of regular training. Even low-impact activities like walking with blood flow restriction has shown to improve muscle girth and strength in patients with muscle atrophy.
- Increasing performance and endurance – with the decreased supply of energy and oxygen and extra metabolites, the muscles get taxed and fatigued. This training method is effective for lightweight work; adding it to heavyweight work (70-80% of your 1RM) puts your muscles through quite the strenuous ride. Naturally, this increases the endurance and stamina of your muscles.
Disadvantages of BFR Training
Just as with any form of physical activity, there will be pros and cons. The cons of BFR training are similar to that of regular training. There is increased strain on the muscles when doing lesser strenuous activity, which can make exercise feel more intense or uncomfortable. Bruising and numbness may be common, but it is only temporary. Regarding additional risks resulting from BFR training itself, there is no conclusive evidence that it carries the risk of injury or problems. However, as with all new training methods, it is advised to follow professional advice when integrating BFR training into your regime. And of course, it is recommended for those with injuries or conditions to perform blood flow restriction therapy under the watchful eye of an experienced practitioner.
So as we’ve now found, BFR is an effective training method with many benefits, especially in those battling against muscle atrophy or in recovery from a sudden injury or prior condition! It definitely provides a remarkable opportunity to increase muscle hypertrophy with minimal weight resistance. As little as 20% of your 1 rep max with BFR can deliver equal (if not more) muscle growth! It’s no wonder it’s been utilized and studied as extensively as it has been since the 1960s.
For those only looking to increase muscle endurance and hypertrophy, it’s also rather inexpensive to employ this training method. Another quick google search has found plenty of inexpensive bands for BFR training on the market. However, the gear ranges from adjustable bands all the way to actual pressure cuffs that sync to your phone with an electronic reading of your blood pressure.
We would love to hear your thoughts or experience with BFR training, whether it’s for muscle growth or injury recovery! Feel free to leave a comment about either below.
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