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. Leal-Junior ECP, Vanin AA, Miranda EF, de Carvalho PTC, Dal Corso S, Bjordal JM. Lasers in Medical Science, 2015; 30: 925–939.
What kind of paper this is
A systematic review with meta-analysis, the design that pools every qualifying randomized trial on a question and asks what the combined data say. Here the question was whether light applied to muscle changes exercise performance and recovery, across both laser and LED sources.
What was pooled
- Performance outcomes: number of repetitions to fatigue and time to exhaustion under controlled exercise protocols.
- Recovery outcome: creatine kinase activity, a standard blood marker of exercise-induced muscle damage.
- Sources: randomized placebo-controlled trials using red and, predominantly, near-infrared wavelengths applied directly over the exercised muscles.
Findings
The pooled data favored phototherapy on both fronts: improved muscular performance and accelerated recovery markers versus placebo. The distinctive conclusion was timing, effects were found mainly when light was applied before exercise rather than after. Preparation, not repair, is where this meta-analysis located the signal.
Limits worth stating
- Individual trials were small and their parameters heterogeneous; the pooled result establishes direction more confidently than dose.
- Outcomes were measured in controlled exercise settings, largely in young healthy or athletic participants.
- A meta-analysis inherits every bias of its inputs; the authors' own parameter recommendations are proposals, not settled prescriptions.