Phototherapy Improves Muscle Recovery and Does Not Impair Repeated Bout Effect in Plyometric Exercise

Objective

Researchers investigated whether phototherapy (photobiomodulation/PBM) could improve muscle recovery after intense plyometric exercise while preserving the body's natural adaptation process known as the repeated bout effect. The repeated bout effect refers to the body's ability to become more resistant to muscle damage after repeated exposure to strenuous exercise.

Study Design

Participants performed demanding plyometric exercise designed to induce muscle damage and soreness.

Researchers compared:

• Phototherapy treatment
• Placebo/sham treatment

They evaluated recovery over time using measures of:

• Muscle soreness
• Muscle function
• Recovery performance
• Exercise-induced muscle damage markers

What Researchers Measured

The study assessed:

• Muscle soreness
• Recovery of muscle performance
• Functional recovery after exercise
• Effects on adaptation to repeated exercise sessions
• Exercise-induced muscle damage responses

Key Findings

Researchers found that phototherapy:

• Improved post-exercise muscle recovery.
• Reduced some markers associated with exercise-induced muscle damage.
• Helped support recovery without interfering with normal training adaptations.
• Did not impair the repeated bout effect, meaning participants still maintained the body's natural protective adaptation to exercise.

This finding is important because some recovery methods may reduce inflammation so aggressively that they potentially interfere with training adaptations. Researchers found that phototherapy improved recovery while still allowing beneficial physiological adaptations to occur.

Why Red Light May Improve Recovery

Researchers noted that photobiomodulation may support recovery through mechanisms such as:

• Increased mitochondrial ATP production
• Enhanced cellular energy availability
• Improved tissue repair processes
• Reduced oxidative stress
• Modulation of inflammatory responses
• Improved muscle recovery after strenuous activity

These effects may help athletes recover faster between workouts while maintaining performance.

Importance for Athletes

One concern with certain recovery interventions is that they may blunt beneficial training adaptations. This study suggests that phototherapy may provide recovery benefits without reducing the body's ability to adapt and become more resilient after intense exercise.

This makes photobiomodulation particularly appealing for:

• Athletes
• Strength training programs
• High-frequency training schedules
• Recovery-focused performance protocols

Conclusion

Researchers concluded that phototherapy improved muscle recovery after plyometric exercise and did not interfere with the repeated bout effect. The findings support the use of photobiomodulation as a recovery strategy that may help reduce exercise-related muscle stress while preserving natural training adaptations.

https://pubmed.ncbi.nlm.nih.gov/33273302/