Blood-Flow Restriction Training

Blood Flow Restriction, Beyond Just Muscle

Author: Johnny Owens, PT, MPT

Muscle tissue requires a stress input to adapt. The traditionally accepted standard for exercise prescription to target muscle size and strength is load based, with physiologic guidelines recommending 65% or more of a one-repetition maximum to create adaptation. It is thought that BFR works through similar physiological pathways and creates a “signal” that is similar to high-intensity exercise.  

But that is not where the benefits of BFR end. There is growing evidence that BFR stimulates tissue such as tendon, bone, and vasculature to adapt positively. There may also be acute physiological benefits in the ability to target analgesia or pain relief.

BFR and Effects on Pain

One of the most clinically relevant effects of BFR is its ability to manipulate pain. The effects of BFR on pain have been shown in healthy individuals, patients with anterior knee pain, and patients rehabbing after ACL reconstruction. The mechanisms driving BFR’s effects on analgesia may involve endogenous opioid release and conditioned pain modulation. Preliminary research has shown that higher relative BFR pressures are more effective than lower pressures, and the effects from a single exercise may last up to 24 hours.

BFR for Tendon and Bone

Tendon and bone are thought to be very load-dependent tissues that require a significant amount of mechanical stress to see beneficial effects. But do they? 

BFR with low-intensity resistance exercise has yielded similar increases in tendon cross-sectional area and stiffness when compared with high-intensity resistance exercise, a result discussed in this 2019 study from the Journal of Applied Physiology. Similarly, physiological markers for bone adaptation increase with BFR and high-intensity exercise, and recent evidence has demonstrated a sparing effect of bone loss if BFR is used after surgery.

BFR and Vasculature

For positive effects to be seen in tissue such as muscle, there has to be a corresponding positive effect on the vasculature. BFR has already been shown to stimulate improvements in blood flow in healthy, older individuals and in clinical populations. Similar to the effects on pain, BFR at higher relative pressure may be most effective for angiogenesis or vascular adaptation, since one of the primary drivers for vascular change is hypoxia.