By Dev K. Mishra, M.D.
President, Sideline Sports Doc
Clinical Assistant Professor of Orthopedic Surgery, Stanford University
- Blood flow restriction (BFR) is a new type of low load lower extremity strength training
- BFR training has the potential for strength gains equivalent to traditional methods but without the knee pain often felt with traditional strength training
Orthopedic surgeons will commonly recommend lower extremity strengthening for any of their patients with chronic painful conditions and almost everyone who’s had knee surgery. Strength gains and strength symmetry are necessary for proper function but individuals who have one of these conditions frequently report one common drawback: the exercises needed to increase muscle strength often lead to significant knee pain.
Blood flow restriction (BFR) training is becoming increasingly popular as a means of strengthening using low loads and without the same type of risk of increased joint pain found with traditional methods of strength training.
There is a growing body of scientific knowledge showing the effectiveness of blood flow restriction training. If you need to gain strength due to an ongoing knee condition or recent knee surgery, I would recommend that you have a close look at this new and effective training method.
BFR training has been around for a few decades but like many things in the world of fitness, early use was limited to a relatively small number of hard-core believers. As word spread the number of users increased, and then folks started correctly asking the right types of questions. Does it really work? Is it safe? How exactly does it work?
For anyone interested in having a look at the available published literature specific to knee injuries and chronic knee conditions here is a nice recent review article. I recommend BFR for my patients with these very common conditions:
- Patellofemoral pain in young athletes
- Active adults with knee osteoarthritis
- Recovery after knee surgery such as ACL reconstruction, meniscus surgery, and knee replacement
Let’s take a look at some of the questions I’ve noted above.
Traditional thinking about strengthening shows that you’d need to work out at about 60% to 70% of your one rep max to increase strength, and 70% to 85% of your one rep max for muscle hypertrophy. In BFR training, a strap similar to a tourniquet is applied to the upper thighs and the upper arms, and the user exercises at about 30% of their one rep max.
The quality of the available scientific studies varies widely, and much additional research is needed, however there is good evidence showing increased strength gains with BFR comparable to those achieved with traditional training protocols. Certainly there is a vast amount of individual anecdotal evidence about its effectiveness.
Regarding safety, there are remarkably few reports in the published literature about problems using BFR. Having said that, this is very new technology to most people and almost everyone will be unfamiliar with how to do this technique. For that reason I recommend to all of my patients considering BFR that they work with a skilled physical therapist who has knowledge in this technique specific to knee conditions and can guide them in appropriate and safe usage.
The exact reasons behind the effectiveness of BFR are not fully known at this point. Here are some of the reasons that have been postulated by scientific researchers:
- Hormonal effects. The BFR appears to increase naturally occurring growth factors such as HGH and VEGF.
- Changes in local oxygenation/lactate buildup. These changes are helpful in gaining muscle strength and with BFR they happen at much lower resistance loads.
- With lower loads a knee joint has a lower chance of becoming painful during exercise, so people are more likely to stick with the exercise.
- There may be local nerve-related pain reduction taking place with BFR compared to traditional training.
This new training technique is very exciting and I believe it has the potential to benefit many individuals with different types of knee conditions. I would strongly recommend that you discuss this with your orthopedic surgeon, sports medicine specialist, and physical therapist.