Effect of phototherapy (low-level laser therapy and light-emitting diode therapy) on exercise performance and markers of exercise recovery: a systematic review with meta-analysis

Abstract

Recent studies have explored if phototherapy with low-level laser therapy (LLLT) or narrow-band light-emitting diode therapy (LEDT) can modulate activity-induced skeletal muscle fatigue or subsequently protect against muscle injury. We performed a systematic review with meta-analysis to investigate the effects of phototherapy applied before, during and after exercises. A literature search was performed in Pubmed/Medline database for randomized controlled trials (RCTs) published from 2000 through 2012. Trial quality was assessed with the ten-item PEDro scale. Main outcome measures were selected as: number of repetitions and time until exhaustion for muscle performance, and creatine kinase (CK) activity to evaluate risk for exercise-induced muscle damage. The literature search resulted in 16 RCTs, and three articles were excluded due to poor quality assessment scores. From 13 RCTs with acceptable methodological quality (≥6 of 10 items), 12 RCTs irradiated phototherapy before exercise, and 10 RCTs reported significant improvement for the main outcome measures related to performance. The time until exhaustion increased significantly compared to placebo by 4.12 s (95% CI 1.21-7.02, p < 0.005) and the number of repetitions increased by 5.47 (95% CI 2.35-8.59, p < 0.0006) after phototherapy. Heterogeneity in trial design and results precluded meta-analyses for biochemical markers, but a quantitative analysis showed positive results in 13 out of 16 comparisons. The most significant and consistent results were found 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). We conclude that phototherapy (with lasers and LEDs) improves muscular performance and accelerate recovery mainly when applied before exercise.

Time response of increases in ATP and muscle resistance to fatigue after low-level laser (light) therapy (LLLT) in mice

“…Increased Cox activity resulting in more ATP synthesis has been the principle explanation in studies that have used LLLT to increase muscle performance before (muscular pre-conditioning) or after (muscle recovery) different types of exercise [15][16][17]. Combined with other metabolic products as lactate and accumulation of adenosine diphosphate (ADP), ATP synthesis is important for optimum muscle performance since reduced levels of ATP in muscles have been held responsible for lowered resistance of muscles to fatigue and decreased performance in many types of exercise [18].…”

“…However, several drugs have been prohibited from being used for this purpose as they are considered "doping" [19]. With this perspective in mind, over the last decade, some researchers have used light therapy to promote muscular pre-conditioning and to increase performance in intense exercise [15][16][17]. These reports have found good effects with this regimen of light therapy in muscular pre-conditioning, preventing muscle damage, and increasing the number of repetitions in fatigue tests.…”

Light-emitting diode therapy (LEDT) before matches prevents increase in creatine kinase with a light dose response in volleyball players

“…Recently, LLLT has been used to increase muscle performance [10,11]. When applied after exercise, LLLT promoted reduction of fatigue [12] and increased the workload in maximum effort tests [13] after training programs.…”

“…When applied after exercise, LLLT promoted reduction of fatigue [12] and increased the workload in maximum effort tests [13] after training programs. When applied before the exercise (muscular pre-conditioning), LLLT increased the number of repetitions and was able to promote Bmuscle protection^against exercise-induced muscle damage [10,11] measured by a lower increase of creatine kinase (CK) levels in the blood. In this context, it is valuable to highlight that CK is an important enzyme of the energy metabolism located inside muscle cells, but its increase in the bloodstream after a bout of exercise is an indicative of rupture of muscle cell membrane and consequently muscle damage [14].…”

“…These studies have evaluated different wavelengths and different light sources such as diode lasers and light-emitting diodes (LEDs) [29]. Three recent studies [10,11,30] reported fascinating results and point to the effectiveness of muscular pre-conditioning using diode lasers and LEDs to prevent muscle fatigue and muscle damage (CK) when applied before (5 min) a bout of exercise.…”