Low-level laser therapy given before exercise improved lower-limb muscle strength in athletes at 24 h, 48 h and 96 h and after 8 weeks, and lowered soreness and creatine kinase, in a meta-analysis of 24 randomised and crossover trials; the abstract gives no effect sizes, and repetitions and VO2 kinetics only trended towards benefit
Main caveat: The authors' own: a definite effect is not established; larger, better-designed trials are needed.
Luo and colleagues pooled randomised controlled and crossover trials of low-level laser therapy in athletes, noting that an earlier meta-analysis had covered healthy people but not physically active athletes. They searched three databases to December 2020, rated risk of bias by the Cochrane Handbook method and included 24 studies.
Laser applied before exercise improved lower-limb muscle strength at follow-ups of 24, 48 and 96 h and 8 weeks; soreness, serum creatine kinase, interleukin-6 and thiobarbituric acid reactive substances (an oxidative-stress marker) were lower; repetitions and VO2 kinetics trended towards improvement.
The authors write that a definite effect is not yet established, that the current evidence supports LLLT for muscular performance in physically active athletes, and that larger, better-designed trials are needed before strong recommendations.
Participants
24 studies in athletes ("physically active athletes" in the authors' words); numbers of participants, sports, sex split and level are not in the abstract.
Protocol
Search: PubMed, EMBASE and Cochrane Library, published trials to December 2020.
Inclusion: randomised controlled trials and crossover studies of LLLT in athletes.
What was applied: low-level laser before exercise; the abstract does not give the wavelengths, doses, body sites, contact with the skin, or how long before exercise. Whether LED devices were included is not stated.
Comparison: not stated in the abstract (placebo presumed from the trials' design, not confirmed).
Outcomes: lower-limb muscle strength at 24 h, 48 h, 96 h and 8 weeks; soreness index; serum creatine kinase, interleukin-6 and thiobarbituric acid reactive substances; repetitions; VO2 kinetics.
Risk of bias: Cochrane Handbook method for randomised trials; the result is not in the abstract.
Key Results
| Outcome (laser before exercise vs control) | Result in the abstract |
|---|---|
| Lower-limb muscle strength, 24 h, 48 h, 96 h and 8-week follow-up | significantly improved; size not given |
| Soreness index | decreased; size not given |
| Serum creatine kinase | decreased; size not given |
| Interleukin-6 | decreased; size not given |
| Thiobarbituric acid reactive substances | decreased; size not given |
| Number of repetitions | trend towards improvement, not significant |
| VO2 kinetics | trend towards improvement, not significant |
No effect sizes, intervals, heterogeneity or study counts per outcome in the abstract.
Practical Application
Low-level laser before exercise (body site not in the abstract) went with better leg strength in the following days and after 8 weeks, and less soreness, in athletes; the abstract gives no effect sizes and the authors themselves say a definite effect is not established. Creatine kinase, interleukin-6 and the oxidative-stress marker are markers, not recovery itself (PHYS-44).
Inference, not tested here: the 24-96 h strength results most likely describe recovery of strength after a demanding bout of exercise, but the abstract does not say what that exercise was; it is not a test of a faster next race.
Different from the base's recovery evidence: in competitive endurance athletes, no recovery modality beat passive recovery on next-session performance (REF-1090); laser therapy was not among that review's modalities (its "far-infrared therapy" is a different treatment), so this review neither confirms nor overturns it.
Under SYNTH-83: "small trials suggest less soreness and better strength recovery with laser treatment before exercise, size unknown", not "it works" and not "a myth".
Limitations
The authors' own: a definite effect is not established; larger, better-designed trials are needed.
No effect sizes, intervals, heterogeneity, participant numbers or risk-of-bias results in the abstract; the "trends" are non-significant results.
The device settings, body sites, timing before exercise and the control condition are not described in the abstract.
The abstract names no earlier review; the one in healthy people it mentions is probably REF-1764 Vanin 2018, and the trials likely overlap with it and with later photobiomodulation meta-analyses (REF-1766 Dutra 2022, REF-1769 Qiu 2026, REF-1774 Zhai 2026) (our reading; overlap not stated), so these reviews are not independent confirmations.
Funding and conflicts of interest are not in the abstract. Written from the abstract and the PubMed record; full text not read.
How this entry was checked and changed
Why this level
a meta-analysis of randomised and crossover trials, risk of bias not read (abstract only); the soreness and creatine kinase results also rest on a self-report and a marker
Content correction 2026-11-11
2026-11-11: added from the abstract and the PubMed record; level B+ (meta-analysis of randomised and crossover trials, risk of bias not read).