Photobiomodulation (red light therapy) may support recovery after exercise. Digest
Delayed-onset muscle soreness (DOMS) can emerge after strenuous exercise and leave muscles sore and weaker for days. A new meta-analysis asked whether targeted light-based therapy could reduce that soreness or preserve muscle strength during recovery.
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The evidence came from 13 randomized trials comparing photobiomodulation therapy (PBMT), applied before or after exercise, with sham light treatment. Muscle recovery was assessed using self-reported soreness, algometry, which measures the pressure at which pain is first felt, and peak torque, the greatest rotational force produced during a muscle contraction. PBMT is an umbrella term for distinct treatment protocols that use low-level lasers or LEDs to expose tissue to red or near-infrared light, rather than a single standardized treatment. The evidence focused mainly on healthy, active men and lower-limb muscles, with fewer studies involving women or other participant groups. The studies also varied in whether they used laser therapy, LED therapy, or a combination of both.
- Peak torque was higher with PBMT than with sham treatment: immediately after exercise and at 24, 48, 72, and 96 hours.
- PBMT groups reported less soreness than sham groups immediately after exercise and at 24 hours. There were no clear differences between the groups at 48, 72, or 96 hours.
- Algometry showed higher pressure-pain thresholds with PBMT than with sham treatment immediately after exercise and at 48, 72, and 96 hours, but no clear difference at 24 hours.
- Exploratory dose comparisons did not show a consistent relationship between PBMT dose, expressed as the total energy delivered to each treated site, and treatment effect. Some studies reported favorable results at doses of 300 joules per treated muscle area for self-reported soreness, 180 or 300 joules for algometry, and 180–300 joules for peak torque.
One possible explanation for these findings is that the photons delivered through PBMT may be absorbed by cytochrome c oxidase, an enzyme found in mitochondria, the parts of cells that help convert nutrients into usable energy. This may alter several linked mitochondrial processes in ways that could support energy metabolism during recovery, allowing mitochondria to work more efficiently and provide recovering tissue with more energy. These mitochondrial effects may occur alongside other changes involving inflammation, local circulation, or sensitivity to pain.
These findings should be interpreted cautiously because PBMT treatment parameters varied substantially across studies and may influence its biological effects. Overall, the study suggests that PBMT may aid recovery, but the findings do not support a single standardized regimen for all populations, muscle groups, or treatment settings. Visit our PBMT topic page for an overview of its mechanisms, potential benefits, and clinical applications.