Muscle Recovery

Improving muscular recovery following exercise is an area of great interest to many clinicians and athletes.

Theoretically LLLT should be able to achieve this, however, most clinical lasers have been small units unable to cover a large enough area (in a suitable time frame) to achieve the goals of increased muscle recovery.

More recently larger devices have become available and once again devices now vary as to the light they emit.

In 2015 Leal-Junior et al. performed a review of the available literature on LLLT and recovery from exercise. They found the most significant and consistent results were with red or infrared wavelengths and phototherapy application before exercises, power outputs between 50 and 200 mW and doses of 5 and 6 J per point (spot). They concluded that phototherapy (with lasers and LEDs) improves muscular performance and accelerates recovery mainly when applied before exercise.

Photobiomodulation therapy (PBMT) studies (with both low-level laser therapy and light-emitting diode therapy) have demonstrated positive scientific evidence to suggest its use in both anaerobic and aerobic activities.

De Paiva et al. (2016) looked at skeletal muscle recovery after eccentric contractions of knee extensors. In a RCT they tested exercise performance (maximum voluntary contraction (MVC)), delayed onset muscle soreness (DOMS), and muscle damage (creatine kinase (CK)). They looked at baseline; immediately after, and at 1, 24, 48, 72, and 96 hours after exercise. They used a combination LLLT (905 nm super-pulsed laser and 875-nm and 640-nm light-emitting diodes (LEDs)).

They found that LLLT alone was optimal for post-exercise recovery with improved MVC, decreased DOMS, and decreased CK activity (p < 0.05) from 24 to 96 hours compared to placebo, cryotherapy, and cryotherapy + LLLT. 

They conclude that LLLT used as single treatment is the best modality for enhancement of post-exercise restitution, leading to complete recovery to baseline levels from 24 hours after high-intensity eccentric contractions.

In 2017 De Marchi et al. found similar results in another RCT, with LLLT beating cryotherapy in recovery.

So do we need really powerful LLLT?

For muscle recovery De Oliveira et al. (2017) said not. In fact, in a 810nm based system they found LLLT increased MVC and decreased DOMS and levels of biochemical markers (p < 0.05) with the power output of 100 and 200 mW, with better results for the power output of 100 mW. So lower appears to better (but would take longer as they recommended 10J overall)

So LLLT appears to work in anaerobic training. What about aerobic?

Miranda et al.  (2017) looked at LLLT in recovery after long distance running. They used 17 sites on each lower limb, using a cluster of 12 diodes: 4 × 905 nm super-pulsed laser diodes, 4 × 875 nm infrared LEDs, and 4 × 640 nm red LEDs, dose of 30 J per site either before and/or after exercise over a 12 week period (3x training per week). They performed assessments pre trial and after 4, 8, and 12 weeks of training. The outcomes assessed were time until exhaustion, oxygen uptake and body fat.

LLLT applied before and after aerobic exercise training sessions significantly increased (p < 0.05) the percentage of change of time until exhaustion and oxygen uptake compared to the group treated with placebo before and after aerobic exercise training sessions (placebo before + placebo after group) at 4th, 8th, and 12th week. Body fat improved compared to the group treated with placebo before and after aerobic exercise training sessions (placebo before + placebo after group) at 8th and 12th week. The LLLT group had increased the time-to-exhaustion and oxygen uptake and also decrease the body fat in healthy volunteers when compared to placebo irradiation before and after exercise sessions.

They concluded that the outcomes show that LLLT applied before and after endurance-training exercise sessions leads to improvement of endurance three times faster than exercise only.