Is red light therapy beneficial for exercise performance and recovery?

Due to its suspected ability to increase cellular energy production, red light therapy has been investigated as an ergogenic aid, with studies typically exposing the working muscle to light immediately before exercise.

Red light therapy has been shown to slightly increase the number of repetition to failure on eccentric exercises (e.g., bicep curls and knee extensions), although this finding is based in large part on studies involving young male volleyball players performed by a single research group.^[1]

Only a couple of long-term studies have looked at whether red light therapy can increase strength and muscle gains when added to regular resistance training. One study in young men found red light therapy before strength training led to greater increases in muscle size and strength,^[2] whereas a study in older men found it had no benefit.^[3] Finally, one study on older women found red light therapy after strength training did not increase muscle strength (muscle size was not reported).^[4]

Red light therapy before exercise has sometimes been found to increase performance on predominantly anaerobic activities (e.g., cycling or running to exhaustion)^[5][6][7][8] However, this is not a consistent finding.^[9][10][11]

Lastly, red light therapy does not seem to reliably reduce muscle soreness in the days following a workout.^{[12][13][14][14]}