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

Abstract

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.

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

“…However, Nampo et al [1] dismissed results of strength from Baroni et al [7] (see Table 1 in Nampo et al [1]), despite authors have highlighted it as the most important finding in that study. Summarily, subjects treated with pre-exercise LLLT had significantly smaller levels of strength loss than those treated with placebo until 48 h post-exercise [7].…”

“…The recently published systematic review with meta-analysis by Nampo et al [1] about the effects of phototherapy using low-level laser therapy (LLLT) or light emitting diodes therapy (LEDT) on delayed onset muscle soreness (DOMS) was critically reviewed by our research team as we have performed many studies in this specific area of research. The study suggests a conflicting conclusion than the previous released systematic review [2] and a meta-analysis [3] that suggested positive effects of phototherapy (or photobiomodulation therapy) on skeletal muscle performance and recovery.…”

“…In Nampo et al [1], DOMS is erroneously defined in the very first sentence of the article: "The soreness perceived while or after participating in exercises." If a subject feels pain "during" the activity, it cannot be defined as a "delayed" response.…”

“…This is a consequence of the microscopic injuries at muscular and connective tissues due to the execution of an unaccustomed exercise, a phenomenon usually called "exercise-induced muscle damage" (EIMD) [5]. Therefore, Nampo et al [1] deals with the effect of phototherapy on indirect markers of EIMD, which have included DOMS in only a third of the trials assessed in this review.…”

“…Some studies included by Nampo et al [1] were clearly more focused on the phototherapy effects over the exercise performance and/or muscle fatigue than EIMD (or DOMS). For example, an insignificant level of muscle damage is expected with six jumps in university athletes [9] or with a 1-min isometric contraction in healthy students [10].…”