In the gym world, blood flow is believed to be one of the key drivers of muscle growth. There are whole programs designed around increasing blood flow to muscles and a myriad of supplements aimed at doing the same. This is where throwing around a term like blood flow restriction (BFR) training gets people's defences up. But hear me out.
Blood transports vital nutrients and oxygen crucial for our muscles to grow, so it's understandable to think at first utterance BFR sounds counterproductive. But what if I told you that restricting blood flow is a very useful technique for growing muscle and there is a lot of science to support this assertion? Let's take a look at what it is, how it works and how to incorporate it into your training.
Blood Flow Restriction Training: What Is It?
In short, BFR is restricting blood flow (obviously) to the muscle you are training. This is usually done with a tourniquet of some kind (see photo below), most commonly an elastic knee wrap or one that has been cut in half (although some fancier implements exist these days).
BFR is predominately utilised on muscles such as biceps, triceps, quad's, hamstrings and calves. As BFR involves restricting the blood flow to muscles below a joint, for obvious reasons it cannot work on muscles on the back or chest.
The goal of BFR is to restrict the venous blood flow (which is blood that is flowing back to the heart) while not impeding arterial blood flow (blood that is flowing into the muscle you are training). This means blood can enter the muscle, but can't escape, causing it to pool.
How Does It Work?
There are a number of ways that BFR training can aid muscle growth, one of these is through targeting specific muscle fibers. As you are probably aware, muscles are made up of different fibers. When we perform resistance training with heavy loads our body recruits fibers in a certain order. Firstly, slow twitch fibers that use oxygen are recruited to move the weight. Near the end of our set when we do our final reps, and the slow twitch fibers fail, we recruit our fast twitch fibers.
Fast twitch fibers have the most potential for muscle growth. When we perform BFR training we inhibit oxygen's ability to get to the muscle. This means that slow twitch fibers fail a lot quicker and our fast twitch fibers are forced to pick up the load under much less weight and intensity. This means that you can achieve a similar effect to training heavy, training with much lighter loads.
Another way that BFR stimulates growth is through metabolic by-products. If you aren't aware, metabolic by-products produced by training play an important role in muscle growth. As mentioned, BFR largely stops venous blood from escaping the muscle you are training. This means that the metabolic by-products that would normally escape, pool in the muscle allowing you to reap the benefits to a much largely degree.
How To Do It!
By now you should have a basic idea of what BFR is and how it works. Now we are going to have a look at how to actually do it.
As mentioned previously BFR involves the use of a tourniquet to impede blood flow to the muscle you are training. Knee wraps are the most commonly used implement, but anything can be used, as long as it can be wrapped around the muscle several times. The tourniquet should be wrapped as close to the joint as possible. For example, if you were using it on the arms you would wrap it at the top of the arm, just below your shoulder.
The goal is to still allow arterial blood flow while restricting venous blood flow. This is best achieved by wrapping the tourniquet at around 70% of maximum. On a scale of 1-10, 10 being maximum tightness, you want to aim to be around 7.
How To Use It In Your Training
The benefit of BFR is it achieves similar effects on muscle growth as heavy training, using much lighter loads and intensities. This is not to say that it should replace heavy training altogether, but it can be a handy supplement.
If you have an injury that prevents you from training heavy, BFR can be a great option. It is also great to incorporate at the end of workouts when energy is running low. But don't let the lighter loads deceive you, BFR is one of the most painful and brutal training protocols around.
BFR is most commonly used on single joint exercises like leg extensions, leg curls, biceps curls and triceps extensions. When choosing a weight it is recommended you use around 30-50% of your one rep max on that exercise. Perform around 3-5 sets of the exercise to failure with around 30-40 seconds rest in between, keeping the muscle wrapped the entire time and only removing it after the final set. If you've done it right, removing the tourniquets should be one of the most relieving feelings on the planet!
BFR can be an extremely useful tool in your training. It allows you to reap the benefits of heavy training without the physical and mental fatigue. It's important to adhere to the correct protocol as restricting blood flow can be problematic if it's done for excessive amounts of time.
Be prepared for a world of pain, though.