Exercise-Induced Muscle Damage

Joyce Cristina Freitas et al. (2026) · Lasers in medical science

This randomized, sham-controlled trial with 48 physically active young men (45 analyzed for performance, aged 18 to 35) at a Brazilian university explored whether photobiomodulation (PBM) and osteopathic manipulation (OM) change recovery after exercise-induced muscle damage (EIMD). PBM applies red light from light-emitting diodes to the skin, a process the authors link to mitochondrial energy production in muscle fibers. OM is a manual therapy; here it meant high-velocity low-amplitude thrusts, quick, small-range joint manipulations. EIMD is the inflammation, strength loss and raised creatine kinase (CK, an enzyme leaking from damaged muscle fibers) that follow unaccustomed jumping or lowering exercise, usually peaking 24 to 72 hours later. Participants were randomized to placebo, PBM, OM, or PBM plus OM, 12 per group. PBM meant a 650 nm red light device pressed against 16 points on the right thigh and calf (144 joules in total, about 8 minutes). OM meant a lumbar roll and a pelvic manipulation by an osteopath. Both were given once before 100 drop jumps from a 50 cm platform, with sham versions for blinding. CK, quadriceps strength, knee flexibility and horizontal jump distance were measured before, right after, and at 24, 48 and 72 hours. The groups did not differ statistically on any outcome (CK group effect p = 0.950; strength p = 0.283; jump p = 0.199, meaning no measurable difference between the four arms). Within groups, CK rose immediately after exercise in placebo (p = 0.01) and OM (p = 0.02), but only at 24 hours in PBM and PBM plus OM, and the combined group showed a significant fall by 72 hours (p = 0.001, suggesting faster clearance of the damage marker). Strength dropped 6.3% to 12.4% after exercise; in exploratory tests the combined group regained significant strength by 48 hours (p = 0.036) and sat 1.4% from baseline. Jump distance rose 8.5 to 11.9 cm in all groups. CK did not track functional recovery. No adverse events were reported. The authors describe a possible modest, complementary benefit of combining the two approaches, while labeling the strength trend exploratory and non-significant. Limitations include 12 participants per group, a single session, only young men, red light that penetrates tissue less deeply than near-infrared light, and no formal check of blinding. Findings apply to physically active young men under acute jumping stress. The authors propose testing other light wavelengths and doses, repeated sessions, and a broader osteopathic approach in future trials.

Yang Zhu et al. (2026) · PeerJ

This systematic review and meta-analysis pooled 22 randomized controlled trials with 375 mostly male participants to ask when, if at all, a single cold-water immersion (CWI) after exercise helps muscles recover. CWI means immersing the body, from navel depth up to the neck, in water of roughly 5 to 20 degrees C for about 6 to 20 minutes. Exercise-induced muscle damage (EIMD) is the loss of force, soreness and raised creatine kinase (CK, a blood marker leaking from stressed muscle cells) that follows hard or unaccustomed exercise, often with delayed onset muscle soreness (DOMS). Earlier reviews mixed time points, so this one separated results at 0, 24, 48 and 72 hours. The included trials enrolled healthy non-athletes and athletes aged about 16 to 49, who exercised with intervals, simulated matches, distance running or heavy eccentric lifting. After exercise, one group sat in cold water and the comparison group rested seated for a similar time. Researchers measured maximal voluntary isometric contraction (MVIC, the hardest possible static muscle squeeze), countermovement jump (CMJ, jump height as a gauge of explosive power), CK, and soreness on a visual analog scale (VAS, a line marked from no pain to worst pain). Maximal strength was unchanged by CWI (g = 0.08, 95% CI -0.11 to 0.26, p = 0.42; a negligible effect) at every time point. Jump performance was worse immediately afterward (g = -0.68, p = 0.01; a medium-sized drop) and showed no difference by 24 to 48 hours (g = 0.38 at 24 h, p = 0.06; g = 0.06 at 48 h, p = 0.68). CK looked lower after CWI (g = -0.43, p < 0.001; a small effect), but the result shrank to non-significance after correcting for likely missing small studies (g = -0.16, 95% CI -0.44 to 0.12; the original benefit was probably overestimated). Soreness was lower (g = -0.58, p = 0.006; a medium effect), though the trials disagreed widely (I² = 87%) and the certainty of evidence was rated very low. The evidence has clear limits: 362 of 375 participants were male, participants could not be blinded to cold water, several trials were tiny, and only one immersion with follow-up of 72 hours or less was studied. The authors suggest the soreness effect is the most plausible benefit and the temporary jump decrement is the main drawback. Repeated use during training and its effect on muscle adaptation were not examined, and they call for larger trials that include women and standardize temperature and duration.