Photobiomodulation as an Adjunct to Resistance Training in Older Adults: A Systematic Review and Meta-Analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 42473844 · doi:10.1177/25785478261469320
What was done
A systematic review and meta-analysis of randomized controlled trials (RCTs) searched seven major databases through January 2026. The authors evaluated whether photobiomodulation (PBM, via low-level laser therapy or light-emitting diodes) added to periodized resistance training improves maximal strength (1-repetition maximum, 1RM) compared to sham PBM in older adults. Studies evaluating non-periodized resistance loading tasks or other endpoints were analyzed narratively.
What was found
Eleven RCTs (n = 456) were included in total, of which five trials (PBM plus resistance training: n = 74; control: n = 72) met criteria for meta-analysis. Adjunctive PBM did not significantly improve maximal muscle strength compared to sham (SMD = 0.26, 95% CI -0.08 to 0.59; p = 0.14; I² = 4%). Subgroup analyses showed a non-significant trend favoring PBM for unilateral 1RM but no effect for bilateral outcomes, with no significant between-subgroup differences. The unilateral finding was sensitive to individual study removal. Narrative synthesis showed inconsistent potential benefits for fatigue, recovery, or functional measures in frail or critically ill older adults.
Why it matters
This review shows that combining photobiomodulation with resistance training does not produce meaningful additive gains in maximal strength for older adults, questioning routine adjunctive use for strength adaptations.
Limits
The meta-analysis included only 5 small trials totaling 146 participants, leaving statistical power limited and wide confidence intervals that cannot exclude a small effect. PBM parameters and exercise protocols varied, and non-strength outcomes were inconsistently measured across heterogeneous cohorts.