Low-Load Blood Flow Restriction Training for Patellofemoral Syndrome (PFS)

Chronic knee pain can be debilitating, forcing you to reduce your physical activity level, which in turn can lead to other health issues, including metabolic disease and weight gain. Many people turn to drugs and surgery as a first line of action to reduce knee pain, yet those approaches often fall short of eliminating pain and restoring function.

Patellofemoral pain syndrome, sometimes called “runner’s knee” refers to pain in the front of the knee and around the kneecap. The condition is common in athletes in sports that involve running and jumping, and in recreational runners. PFS is caused by overuse and misalignment of the structures of the knee, often due to imbalanced muscle tension or mechanical deficits.

Rehabilitation goals for PFS include

• reduced pain,
• increased quadriceps strength,
• and restored function.

Standard resistance training is a broadly accepted treatment approach for accomplishing those goals. In most cases, loading the quadriceps at 70 percent of one-rep-max (70%/1RM) is effective in strengthening the quads and increasing muscle size (1RM is the maximum load you can lift in one repetition). Most people are able to perform 10 to 12 repetitions at this training load. But for some people, loading at 70%/1RM causes excessive knee pain, ruling it out as a treatment option.

Low-load blood flow restriction (BFR) training is an innovative approach to PFS treatment for patients who cannot tolerate high training loads. The approach uses a blood pressure cuff or band to reduce blood flow to the quadriceps, and training loads are reduced to 30 percent of 1RM. Exercises are performed to volitional fatigue, meaning the exercise is continued until the patient cannot perform another complete repetition.

The mechanisms behind low load BFR training are not entirely clear, yet the approach appears to produce desirable results comparable to traditional resistance training at 70%/1RM.

A recent study by Lachlan et al. (2017) compared the effectiveness of standard resistance training (RT) to low-load BFR training for increasing strength and reducing pain in patients with PFS. Seventy-nine participants with patellofemoral pain were randomly assigned to either standard quadriceps training or low-load BFR. Exercises included one open-chain and one closed-chain exercise (bilateral knee extensions and two-legged leg presses), performed three times per week for eight weeks.

At the end of the training period, 93 percent of the low-load BRF group reported a greater reduction in pain than the standard RT group.