When seeking any intervention to speed up recovery it is critical to have an understanding of how the intervention works, and what potential side effects exist. Photobiomodulation (PBM) has over a 50-year history with no reported nor demonstrated side effects. Equally important, it is critical to find out where any given intervention gets its claims, and from whom. Below are highlights from studies that use PBM before and after exercise, both aerobic and non-aerobic. The Light Lounge™ Resource Center sources its data and research from peer-review journals and unbiased, world-class research institutions. To read more, see what kind of studies have the greatest impact.
In a double-blind, randomized, and placebo-controlled experiment 20 competitive male cyclists (cycling around 162 miles and training more than 4 days per week) came into the lab 2 times over a 5 day period. All participants received either a PBM treatment (at 3 different intensities) or placebo. All participants were blinded with opaque goggles so they couldn't see if the unit was on or off. After the PBM treatment, the participants performed time-to-exhaustion tests (TTE) at their maximal power output (POmax). Essentially, the researchers measured each cyclist's maximal power output, and then each cyclist had to maintain that power output as long as they could.
The study found no changes in power output between the treatment and placebo groups, but the scientists did find a reduction in Oxygen (O2) deficit and an increase TTE in the PBM treatment group (across all intensities). The O2 deficit is the phenomenon where the body produces energy from non-oxygen sources at the beginning of aerobic exercise, eventually, oxygen becomes the sole source of energy. Since PBM acts upon the mitochondria, this study suggests that the cyclists in the treatment group were able to begin consuming oxygen more quickly than the placebo group. The researchers claim that this may have explained the performance-enhancing qualities of PBM which allowed the cyclists in the treatment group to perform longer at their maximal power output.
In another randomized, double-blind study 22 untrained men (20-25 yrs old) had either a PBM treatment or placebo applied to the quadriceps, hamstring, and calf muscles. 5 minutes after the treatment or placebo participants performed a progressive running protocol (increasing running speed) until exhaustion. The PBM treatment participants experienced both an increase in maximal oxygen consumption capacity (VO2max) and TTE. Additionally, the PBM group experienced a decrease in lipid damage (a marker for oxidative stress) and protein damage (i.e. muscle damage). The PBM group experienced no change for additional biomarkers for muscle damage, lactate dehydrogenase and creatine kinase. The placebo group experienced an increase in all damage biomarkers. The PBM group experienced no loss in superoxide dismutase (an enzyme that counteracts oxidative stress during exercise), while the placebo group experienced a decrease of this enzyme. These results demonstrate that PBM can prevent oxidative damage that is usually associated with exercise and can maintain the levels of anti-oxidative enzymes. Since it is known that oxidative stress leads to an impairment of muscle contraction, this study shows that even untrained people can benefit from PBM. They experience performance increases, the reduction of oxidative stress, and protective effects against exercise-induced muscle damage.
The following studies use the MVC (maximal voluntary contraction - the maximal amount of force or torque that a person can develop in a muscle) index which is one of the best clinical methods to quantify muscle injury.
In a double-blind and randomized study, 10 male professional volleyball players performed biceps curls at 75% MVC until exhaustion. Both groups received either PBM or placebo (PBM machine turned off) to their biceps brachii before exercise. The PBM group had a 12.9% higher number of repetitions and a 11.6% longer amount of time doing the repetitions. Blood lactate (a byproduct of non-aerobic energy generation which becomes present when the oxygen-based methods can't keep up) levels were lower in the PBM group. The following biomarkers actually decreased after exercise in the PBM group (they slightly increased in the placebo group): C reactive protein (increases during inflammation) and Creatine Kinase (a protein that is, among other things, a measure of muscle damage after strenuous exercise). This demonstrates that PBM treatment before exercise can delay muscle fatigue by delaying muscle damage and inflammation caused by exercise.
Another weightlifting study found that PBM can decrease the amount of fatigue during knee extension exercises. 17 healthy and active men participated in a randomized and double-blind knee extension study. After finding the MVC for each participant the researchers applied the PBM treatment and placebo (each on the quadriceps). After the intervention, both groups performed 30 maximal knee-extension exercises isokinetically (at the same speed). Interestingly, there was no difference in MVCs between the groups before the fatiguing exercises, the average MVCs were the same between groups. However, after the fatiguing exercises, the PBM group experienced a 5% higher MVC than the placebo group. Since the PBM group experienced a smaller decrease in post-exercise MVCs, the researchers demonstrated that performance can be increased by PBM.
17 untrained men entered a study where they performed 30 MVCs in a row with the biceps brachii (i.e. biceps curls) using their non-dominant arm, isokinetically, with 45 seconds between reps. Immediately after the exercises the men either received placebo or PBM treatment onto the belly of the biceps brachii; participants had opaque goggles to keep them blind. Both groups were tested for strength, muscle soreness, elbow range of motion 24, 48, 72, and 96 hours after the exercise and the treatment. The largest recovery effect was demonstrated after 24 hours using the following measures: muscle soreness, strength loss, and range of motion for the non-dominant arm. This demonstrates a faster recovery with PBM post-exercise.
If you are an athlete (recreational or professional) you know that it takes serious work and patience to experience gains. As one of the authors of the research studies states:
"A fast muscle recovery is important to athletes, especially during competition, since athletes commonly return to training approximately 48 h following competition" -Dr. Borges
As many of you know, experiencing 5-10% gains in performance takes lots of time, especially for athletes who train regularly. These rigorous studies demonstrate that PBM can increase performance, decrease exercise-induced damage, and decrease recovery time. Click on the above links to read the original research.