What is blood flow restriction training? In essence, this training method is exactly what it sounds like: restricting blood flow to the muscles during exercise. This is usually done using special equipment, such as a blood flow restriction (BFR) cuff.
What caught people’s attention were the reported benefits, with claims of BFRs stimulating impressive muscle growth and strength gains from resistance training at lower weights.
It is also recommended that the BFR can be used during low-intensity aerobic activity – such as a session in one of the best walking treadmill (opens in a new tab) – to prevent muscle atrophy or loss in deconditioned people, such as the elderly population and those with injuries.
To separate fact from fiction, we spoke with Jeremy Loenneke, a professor of exercise science at The University of Mississippi, and blood flow restriction training authority.
Jeremy Loenneke is director of the Kevser Ermin Laboratory of Applied Physiology at the University of Mississippi and the main focus of his research group is on adaptation of skeletal muscle to exercise with and without the application of blood flow restriction. He is a Fellow of the American College of Sports Medicine and a Fellow of the American Physiological Society.
What is blood flow restriction training?
As outlined above, BFR involves restriction of blood flow to the working muscle. Loenneke offers this summary. “Blood-flow restriction training involves applying a cuff or wrap to the limb being worked on (for example on the top of the leg or the top of the arm) to partially restrict blood flow to that limb.
“This restriction is combined with low-weight or low-intensity resistance training aerobic exercise (opens in a new tab) to produce similar benefits with high-load or higher-intensity exercise.”
For example, the BFR can be used when doing bicep curls. While doing this exercise, you will place and tighten the cuff around the proximal part of the arm (near the body) to limit blood flow to the working muscle (biceps). Through this, says Loenneke, you can lift lighter weights while experiencing the same thing hypertrophy (opens in a new tab) and the strength benefits of training with heavier weights.
How blood flow restriction training works
How restricting blood flow increases muscle size isn’t completely known, says Loenneke, but it’s likely similar to traditional resistance training.
In other words, when a muscle contracts, it initiates a signal that activates growth-promoting pathways (e.g. mTORC1) in the activated muscle fiber. As the exercise becomes more difficult, more fibers are activated.
“Application of blood flow restriction makes the muscles work harder than normal, leading to higher levels of muscle activation. This means more fibers are signaled to grow, even when the load being lifted is very light (20-30% of maximum strength). “
What equipment is needed?
A cuff or wrap is required to perform blood flow restriction training. And, with the practice’s increasing popularity, many of these products are available commercially – in stores and online. These cufflinks are available in two main styles: inflatable, like B. Strong cuff (opens in a new tab) down and practical.
“There are a number of commercial options available for those interested in implementing blood flow restriction,” says Loenneke. “Main components include the cuff and a device for inflating the cuff.
“Many commercial devices available today also allow for personalized regulation of limb pressure – that is, a pressure that takes into account the cuff being used and the size of the extremity the cuff is using (eg of the pressure required to completely cut off blood flow).
“Another method is to apply a practical restriction of blood flow through an elastic wrap or cuff. This method is called ‘practical’ because elastic wrap is easy to find and inexpensive. The downside of this method is that it doesn’t have a device to regulate pressure, therefore it’s impossible to know how much restriction is being applied.”
What are the benefits?
At first glance, the benefits of restricting blood flow may seem too good to be true: namely, increased hypertrophy and increased strength while lifting lighter weights, thereby lowering the risk of injury for the exerciser and enabling the unconditioned individual to train with greater efficiency. However, there is literature to support this claim.
“Most of the work [studying BFR] has focused on changes in muscle size and strength,” says Loenneke. “Blood flow restriction in combination with low weight resistance training increases muscle size and strength.
“Changes in muscle size are similar to high weights (70% of the heaviest weight a person can lift). However, the change in max power is often lacking – strength is still increasing, just not to the same extent.”
A 2010 study published in Clinical Physiology and Functional Imaging The journal assigned 10 youths to complete four sets of bench presses for a total of 75 repetitions at 30% of the heaviest weight they could lift for one repetition. They did this twice daily, six days a week, for two weeks, with one group using elastic cuffs placed proximally on both arms for BFR and the remaining subjects performing the exercise without the cuff.
After two weeks, the BFR group saw a 6% increase in their maximum bench press, an 8% increase in their triceps muscle thickness and a 16% increase in their pectoralis major muscle thickness (the largest chest muscle).
In contrast, the bench press of the one-rep max control group decreased by 2%, and the thickness of their triceps and pectoralis major muscles remained almost unchanged (-1% and 2 percent, respectively).
This may be partly due to the ability of the BFR to affect the endocrine system. A 2016 study published in European Journal of Applied Physiology (opens in a new tab) found that four weeks of low-intensity resistance training with restriction of blood flow led to a significant increase in growth hormone levels.
The ability to reap similar results from resistance training and other forms of exercise, while using lower weights and reducing stress on the body as a result, could benefit individuals or groups who are unable to participate in more intense activities, Loenneke said.
“There are certain populations who may be able to increase muscle size and strength through slow walking or cycling with restricted blood flow, but the greatest changes occur when blood flow restriction is combined with resistance-type exercise.
“Several studies have shown that applying blood flow restriction by itself may slow the loss of muscle size and strength with bed rest. However, the data for it is very limited.”
Who should do it?
It may not be a mainstream practice among casual sportsmen, but Loenneke says restricting blood flow is something that everyday gym goers looking to increase their strength and muscle mass can use. However, he suggests incorporating it into your workout routine, rather than sticking it at the end of an already full workout schedule.
“[Gym-goers] may use it as part of their normal training program or they may choose to apply it when they are injured or are looking to add some variety to their training,” says Loenneke. “Some like to include it towards the end of the workout after they’ve done some of their traditional training.
“This can be effective, but it’s important to realize that muscles can only respond so much to a given training session. If you’ve already done several sets of several exercises for certain muscle groups, it’s unlikely that adding another exercise with restricted blood flow will add anything extra.
Is blood flow restriction training dangerous?
While all sports have associated risks, many fears about BFR are unfounded, says Loenneke. However, more research is needed.
“Two common concerns are the risk of muscle breakdown and blood clots. Available literature suggests that adding blood flow restriction to exercise does not appear to increase the risk of either. This, of course, assumes that the stimulus is used appropriately. ”
The existing literature supports this. 2021 systematic review of studies into the subject, published in International Journal of Sports Physical Therapy (opens in a new tab), stated: “It appears that the greatest advantage of BFR is its ability to safely increase exercise intensity in healthy, comorbid individuals. However, more research is needed before fully determining the long-term systemic effects of BFR.”