Strengthening the Forces: What is blood flow restricted training?


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By Dr. Darrell Menard OMM MD, Dip Sport Med

Q: I enjoy weight training and have made significant gains since joining the Forces. I’m always looking for new training strategies. While deployed, I was introduced to blood flow restricted training. Have you heard of this type of training? Could you comment if it works and if it’s safe? – Sergeant Strong

A: Dear Sgt Strong, blood flow restricted (BFR) training is also called occlusion or Kaatsu training, and has been around for many years. Its claim to fame is allowing people to make training gains through low-resistance exercise, yet there is cause for concern.

BFR training involves using a tourniquet to restrict blood flow to the arms or legs. The pressure to the limb must be strong enough to stop the return of venous blood from the constricted limb, but not strong enough to stop arterial blood flow. This can be difficult to achieve, as the desired pressure can be different for everyone. With the limb constricted, the person does resistance exercises at up to 20 to 30 percent of their one repetition maximum. People typically do three sets of 20 to 30 repetitions at this low resistance. The theory is that doing low-intensity training with restricted blood flow allows people to reach the same training gains they would get from high-intensity training.

Does BFR training work?

Research clearly shows that BFR training offers no advantage for people who can do higher-intensity training, and may even be less effective. Some rehabilitation programs have used BFR training, and found it helpful for those who can’t do higher-intensity training with their arms or legs due to disease or disability.

Is BFR training safe?

Very little research has been done regarding the safety of BFR training, but there are some significant concerns:

  1. Reducing blood flow to working muscles activates a reflex that can put people with high blood pressure, heart disease and poor circulation at increased risk of abnormal heart rates, heart attack, stroke and sudden death. This is concerning because many people have these medical conditions and aren’t aware of them.
  2. We have no idea if there are potential health risks from the long-term use of BFR training.
  3. There is no standardized way to determine the ideal constricting pressure, and using excessive pressure could damage blood vessels, muscles and tendons. It could also cause life threatening blood clots.
  4. This training approach is not recommended for people with the following conditions: pregnancy, a history of blood clots, poor arm and leg circulation, varicose veins, high blood pressure, heart disease, limbs that have had their lymph nodes removed, abnormal heart rates, and people who are on medication that increases the risk of clotting.

The bottom line: BFR training may be a waste of time, and we are uncertain about its safety. The potentially dangerous cardiovascular responses to this technique are such that further research is needed to determine if it can safely be used by those who can’t do high-intensity training due to disease or disability. Train smart.

Exercise is medicine!

Dr. Menard is the Surgeon General’s specialist advisor in sports medicine and has worked extensively with athletes from multiple sports. As part of the Strengthening the Forces team, he works on injury prevention and promoting active living.

Strengthening the Forces is the Canadian Armed Forces (CAF) healthy lifestyles promotion program providing expert information, skills and tools for promoting and improving CAF members’ health and well-being.

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