OBJECTIVE: To assess near-infrared preirradiation effects on postexercise lower-limb muscle damage and function and determine optimal dosage. DATA SOURCES: PubMed, Embase, Cochrane Library, EBSCO, Web of Science, China National Knowledge Infrastructure, and Wanfang Data were systematically searched (2009 to 2023). STUDY SELECTION: Randomized controlled trials of near-infrared preirradiation on lower-limb muscles after fatigue exercise were incorporated into the meta-analysis. Out of 4550 articles screened, 21 met inclusion criteria. DATA EXTRACTION: The included studies' characteristics were independently extracted by 2 authors, with discrepancies resolved through discussion or by a third author. Quality assessment was performed using the Cochrane risk of bias tool and the Grading of Recommendations, Assessment, Development, and Evaluation System. DATA SYNTHESIS: In 21 studies, near-infrared preirradiation on lower-limb muscles inhibited the decline in peak torque (standardized mean difference (SMD) 1.33; 95% confidence interval (CI) 1.08 to 1.59; p < 0.001; increasing 27.97 +/- 4.87 N.m), reduced blood lactate (SMD -0.2; 95% CI -0.37 to -0.03; p = 0.272; decreasing 0.54 +/- 0.42mmol/L), decreased creatine kinase (SMD -2.11; 95% CI -2.57 to -1.65; p < 0.001; decreasing 160.07 +/- 27.96 U/L), and reduced delayed-onset muscle soreness (SMD -0.53; 95% CI -0.81 to 0.24; p < 0.001). Using a 24 hour cutoff revealed 2 trends: treatment effectiveness depended on power and energy density, with optimal effects at 24.16 J/cm2 and 275 J/cm2 for energy, and 36.81 mW/cm2 and 5495 mW/cm2 for power. Noting that out of 21 studies, 19 are from Brazil, 1 from the United States, and 1 from Australia, and the results exhibit high heterogeneity. CONCLUSIONS: Although we would have preferred a more geographic dispersion of laboratories, our findings indicate that near-infrared preirradiation mitigates peak torque decline in lower-limb muscles. Influenced by energy and power density with a 24 hour threshold, optimal energy and power densities are observed at 24.16 J/cm2, 275 J/cm2, 36.81 mW/cm2, and 5495 mW/cm2, respectively. Laser preirradiation also reduces blood lactate, creatine kinase, and delayed-onset muscle soreness.

Full text (sometimes free) may be available at these link(s):      help

• DOI
• PubMed
• PDF locator
• publisher