Pretreatment of Mice with 830 nm Light Enhances Endurance During Acute Exercise.

Light therapy has been shown to produce several beneficial physiological effects in a wide range of tissues. The musculoskeletal system can be irradiated with deeply penetrating wavelengths in near infrared (NIR) regions. Photobiomodulation therapy (PBMT) reduces pain and inflammation and enhances physical performance. However, the mechanism(s) of cellular responses to PBMT in muscle is not clearly understood. Therefore, the goal of this study is to improve our understanding of the mechanism(s) of action of PBMT effects in exercised and sedentary muscle. In sedentary mice, PBMT using a wavelength of 830 nm increased the gene expression for muscle tissue development, including cFos, which is critical for activating interstitial and satellite cells that repair muscle. Immunostaining for cFOS expression confirmed an increase in the number of activated cells in PBMT-treated muscle. We observed that PBMT-treated mice showed increased performance on the treadmill, reduced muscle fiber damage, and altered mitochondrial structure. RNA sequencing from fatigued TA tissue suggested that PBMT treatment increased the gene expression of tissue regeneration and remodeling, suggesting tissue adaptation and muscle repair after exercise with PBMT. In conclusion, our study suggests that the 830 nm wavelength may have altered the muscle by activating regenerative genes that protect the tissue from exercise-induced cellular stress.