Effect of low-level phototherapy on delayed onset muscle soreness: a systematic review and meta-analysis

To determine the effectiveness of low-level phototherapy (i.e. light-emitting diode therapy [LEDtherapy] or light amplification by stimulated emission of radiation therapy [LASERtherapy]) on pain, skeletal muscle injury (creatine kinase [CK] levels and edema) and skeletal muscle function (range of movement and strength) in people undergoing an exercise protocol. (Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PEDro, SciELO and LILACS up to May 2014), we included randomized controlled trials, quasi-randomized controlled trials and crossover studies in which study participants were allocated to receive either low-level phototherapy or placebo treatment. Phototherapy should have been applied in a single treatment session, either before or after an exercise protocol. We identified 15 studies involving 317 participants. Meta-analyses were limited by substantial heterogeneity. Compared to the placebo group, reduction in CK levels was only observed when LASERtherapy was applied before an exercise protocol (standardized mean difference = -0.66; 95 % CI = -1.30, -0.02). No between-group difference in edema, range of movement and strength were detected when phototherapy was applied before or after exercise. Evidence from this review suggests that low-level phototherapy may not have substantial effect in the treatment of skeletal muscle injury and pain caused by exercise. Definitive conclusions are limited due to the small number of included studies in each meta-analysis, disparities across the included studies and small sample sizes

Low-level phototherapy to improve exercise capacity and muscle performance: a systematic review and meta-analysis

The aim of this study was to evaluate the effectiveness of pre-exercise low-level phototherapy (Light-Emitting Diode therapy [LEDtherapy] or Light Amplification by Stimulate Emission of Radiation therapy [LASERtherapy]) in increasing exercise capacity and muscle performance of people undergoing exercise when compared to placebo treatment. Randomized controlled trials and crossover studies were sought on CENTRAL, MEDLINE, EMBASE, SciELO, PEDro and LILACS from its inception up to February 2015. References lists of included studies were sought for additional relevant research. Two authors independently extracted data on study design, treatment parameters, exercise capacity (number of repetitions, time to exhaustion, blood lactate concentration and lactate dehydrogenase activity) and muscle performance (torque, power and strength) using an structured table. Agreement should be reached by consensus or by a third reviewer. Sixteen studies involving 297 participants were included. Improvement of number of repetitions (mean difference [MD] [95 % confidence interval] = 3.51 repetitions [0.65–6.37]; P = 0.02), delay in time to exhaustion (MD = 4.01 s [2.10–5.91]; P < 0.0001), reduction in lactate levels (MD = 0.34 mmol/L [0.19–0.48]; P < 0.00001) and increased peak torque (MD = 21.51 Nm [10.01–33.01]; P < 0.00001) were observed when LASERtherapy was applied. LEDtherapy meta-analyses were performed with two studies and retrieved no between-group statistically significant difference in power, lactate levels or time to exhaustion. Although our results suggest that LASERtherapy is effective in improving skeletal muscle exercise capacity, the quality of the current evidence is limited