In recent years, photobiomodulation therapy (PBM) has emerged as a promising non-invasive approach to enhance athletic performance and accelerate postexercise recovery. This technique uses specific wavelengths of light, such as infrared (IR) 810nm, to stimulate cellular processes like adenosine triphosphate (ATP) production and reduce inflammation. However, determining the optimal power output for maximal benefits remains a critical question. A landmark study by de Oliveira et al. (2017) addressed this gap by investigating how different power levels of 810nm IR light affect skeletal muscle performance and recovery in humans. This article synthesizes their findings to provide a clear, evidence-based guide for athletes and fitness enthusiasts.
Understanding Photobiomodulation Therapy (PBM)
PBM, also known as low-level laser therapy (LLLT), involves exposing tissues to low-intensity light (typically 600–1000nm) to trigger beneficial biological responses. The 810nm wavelength is particularly effective for muscle tissue due to its deep penetration (up to 10mm) and ability to target mitochondria—the energy-producing centers of cells. When absorbed by cytochrome c oxidase in mitochondria, 810nm light enhances ATP synthesis, reduces oxidative stress, and promotes blood flow. These effects collectively improve muscle function and speed up recovery after intense exercise.
Study Design and Methods
De Oliveira et al. (2017) conducted a randomized, double-blind, placebo-controlled trial involving 28 high-level male soccer players (age: 22.5 ± 2.8 years). Participants were divided into four groups: three active PBM groups (100mW, 200mW, 400mW per diode) and one placebo group. The intervention involved delivering 10 Joules (J) of energy to six sites on the quadriceps (knee extensor muscles) using a cluster of five diodes emitting 810nm light. The placebo group received sham treatment with no active light. Key measurements included:
• Muscle strength: Maximum isometric voluntary contraction (MIVC) of the quadriceps.
• Delayed onset muscle soreness (DOMS): Self-reported pain on a 10-point scale.
• Biochemical markers: Creatine kinase (CK), lactate dehydrogenase (LDH), inflammatory cytokines (IL-1β, IL-6, TNF-α), and oxidative stress indicators (catalase, superoxide dismutase).
Measurements were taken before exercise, immediately post-exercise, and at 1, 24, 48, 72, and 96 hours afterward. The exercise protocol involved eccentric contractions (lengthening muscle actions) to induce muscle damage and fatigue, mimicking typical sports-related stress.
Key Results
1. Muscle Performance
• MIVC Recovery: The 100mW group showed significantly faster recovery of muscle strength. By 72 hours post-exercise, their MIVC had rebounded to 95% of pre-exercise levels, compared to 85% in the placebo group. The 200mW group also improved but lagged behind the 100mW group (90% recovery). The 400mW group showed no significant difference from the placebo.
• DOMS Reduction: The 100mW group reported 30% less soreness at 48–72 hours post-exercise compared to the placebo. This reduction correlated with faster functional recovery, allowing athletes to resume training sooner.
2. Biochemical Markers
• Muscle Damage: Both 100mW and 200mW groups had lower CK and LDH levels (markers of muscle cell damage) at 24–48 hours post-exercise. The 100mW group’s CK levels peaked at 35% lower than the placebo group.
• Inflammation: IL-6 and TNF-α levels were 25–30% lower in the 100mW group at 24 hours, indicating reduced inflammatory response.
• Oxidative Stress: Catalase and superoxide dismutase activity increased by 15–20% in the 100mW group, highlighting improved antioxidant defense.
3. Power Output vs. Effectiveness
The study revealed a non-linear relationship between power output and outcomes. While 100mW and 200mW were effective, 400mW showed no benefits. This suggests that beyond a certain threshold, higher power may not enhance cellular responses and could even cause unintended heat-related stress.
Why 100mW Is Optimal
The superior results at 100mW can be explained by two key mechanisms:
1. Mitochondrial Activation: At 100mW, 810nm light optimally activates cytochrome c oxidase, boosting ATP production without overwhelming the cell’s energy demand.
2. Balanced Inflammation and Repair: Lower power outputs (100–200mW) promote anti-inflammatory pathways and stimulate satellite cell activity for muscle repair, whereas higher power (400mW) may disrupt this balance.
Additionally, the 100mW dose avoids excessive heat generation. Infrared light at higher power can increase tissue temperature, potentially causing discomfort or tissue damage. The study’s safety assessments confirmed no adverse effects in the 100mW group.
Practical Applications
Based on these findings, athletes and trainers can optimize pre-exercise PBM by:
• Targeting Large Muscle Groups: Focus on quadriceps, hamstrings, and glutes, as these are most prone to fatigue and damage during high-intensity sports.
• Timing: Apply PBM 30–60 minutes before exercise to allow cellular responses to peak during activity.
• Equipment: Use devices with 810nm wavelength and 100mW power per diode, delivering 10J of energy per treatment site.
For team sports like soccer or rugby, a 100mW PBM session could reduce post-match soreness and enable faster return to training. Recreational athletes may also benefit from improved endurance and reduced risk of overtraining.
Limitations and Future Directions
While de Oliveira et al.’s (2017) study provides robust evidence, it has limitations:
• Sample Size: The 28 participants were all male soccer players, limiting generalizability to other populations (e.g., females, older adults).
• Duration: The study only tracked outcomes for 96 hours. Long-term effects of repeated PBM sessions remain unclear.
• Protocol Variability: Different devices or application techniques (e.g., continuous vs. pulsed light) might yield different results.
Future research should explore dose-response relationships in diverse populations and investigate how PBM interacts with nutrition or training protocols.
Conclusion
Pre-exercise PBM with 810nm light at 100mW power per diode offers a safe and effective way to enhance skeletal muscle performance and accelerate recovery. By optimizing mitochondrial function, reducing inflammation, and mitigating oxidative stress, this protocol can help athletes perform better and recover faster. While individual responses may vary, the evidence strongly supports 100mW as the gold standard for maximizing benefits without compromising safety.
References
de Oliveira, A. R., Vanin, A. A., Tomazoni, S. S., Miranda, E. F., Albuquerque-Pontes, G. M., De Marchi, T., ... & Leal-Junior, E. C. P. (2017). Pre-Exercise Infrared Photobiomodulation Therapy (810 nm) in Skeletal Muscle Performance and Postexercise Recovery in Humans: What Is the Optimal Power Output? Photomedicine and Laser Surgery, 35(11), 595-603. https://doi.org/10.1089/pho.2017.4343 (PMID: 29099680)
