Protective effects of photobiomodulation against resistance exercise-induced muscle damage and inflammation in rats

ABSTRACT

We investigated whether low-level laser therapy (LLLT) prior to or post resistance exercise could attenuate muscle damage and inflammation. Female Wistar rats were assigned to non-LLLT or LLLT groups. An 830-nm DMC Laser Photon III was used to irradiate their hind legs with 2J, 4J, and 8J doses. Irradiations were performed prior to or post (4J) resistance exercise bouts. Resistance exercise consisted of four maximum load climbs. The load work during a resistance exercise bout was similar between Control (non-LLLT, 225 ± 10 g), 2J (215 ± 8 g), 4J (210 ± 9 g), and 8J (226 ± 9 g) groups. Prior LLLT did not induce climbing performance improvement, but exposure to 4J irradiation resulted in lower blood lactate levels post-exercise. The 4J dose decreased creatine kinase and lactic dehydrogenase levels post-exercise regardless of the time of application. Moreover, 4-J irradiation exposure significantly attenuated tumor necrosis factor alpha, interleukin-6, interleukin-1β, cytokine-induced neutrophil chemoattractant-1, and monocyte chemoattractant protein-1. There was minor macrophage muscle infiltration in 4J-exposed rats. These data indicate that LLLT prior to or post resistance exercise can reduce muscle damage and inflammation, resulting in muscle recovery improvement. We attempted to determine an ideal LLLT dose for suitable results, wherein 4J irradiation exposure showed a significant protective role.

KEYWORDS:

• Inflammation
• laser
• muscle recovery
• phototherapy
• strength training

Acknowledgments

The authors would like to thank the “Pontual Traduações” by English editing.

Disclosure statement

Ernesto Cesar Pinto Leal-Junior receives research support from Multi Radiance Medical (Solon, OH), a laser device manufacturer. Multi Radiance Medical had no role in the planning of this study, and the laser device used was not theirs. They had no influence on study design, data
collection and analysis, decision to publish, or preparation of the article. The remaining authors declare that they have no conflict of interests.

Additional information

Funding

This study was funded in part by São Paulo Research Foundation - FAPESP (Grant Number 15/11028-9).