Effects of low-level laser irradiation on rat skeletal muscle injury after eccentric exercise.
OBJECTIVE
The effect of photobiomodulation on delayed onset muscle soreness remains unknown. This study represents the first investigation of this treatment using an animal model.


METHODS
Seventy-two Sprague-Dawley rats were randomly divided into five groups: sedentary control group, exercise control group and three exercise-plus-laser groups. Downhill running was used to induce muscle injury in the gastrocnemius muscle. He-Ne laser irradiations were administered to the injured muscles immediately and at 18 and 42 h after exercise in the three exercise-plus-laser groups at 12, 28, and 43 J/cm2, respectively. Histological examination and serum creatine kinase (CK), muscle superoxide dismutase (SOD) and malondialdehyde (MDA) analyses were done at 24 and 48 h after exercise.


RESULTS
The exercise control group exhibited a marked inflammation in the gastrocnemius muscle and significant elevations in serum CK activity and muscle MDA level after downhill running. He-Ne laser irradiation at 43 J/cm2 inhibited muscle inflammation, significantly enhanced muscle SOD activity and significantly reduced serum CK activity and muscle MDA level at both 24 and 48 h after exercise, whereas the irradiation at 12 or 28 J/cm2 slightly inhibited muscle inflammation and significantly reduced serum CK activity at 48 h after exercise only (P<0.05).


CONCLUSIONS
Low-level He-Ne laser therapy could exert therapeutic effects on eccentric exercise-induced rat muscle injury through enhancing muscle anti-oxidative capacity and reducing the inflammatory reaction. The photobiomodulation was dose-dependent, and the 43 J/cm2 dose was the most efficient among the doses used.
Liu
Xiao-Guang
XG
Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China.
Zhou
Yong-Jian
YJ
Liu
Timon Cheng-Yi
TC
Yuan
Jian-Qin
JQ
D000704:Analysis of Variance; D000818:Animals; D003402:Creatine Kinase / Q000097:blood; D004307:Dose-Response Relationship, Radiation; D005260:Female; D007249:Inflammation / Q000532:radiotherapy*; D028022:Low-Level Light Therapy / Q000379:methods*; D008315:Malondialdehyde / Q000378:metabolism; D018482:Muscle, Skeletal / Q000293:injuries* / Q000378:metabolism; D010805:Physical Conditioning, Animal; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013482:Superoxide Dismutase / Q000378:metabolism
D008315:Malondialdehyde; D013482:Superoxide Dismutase; D003402:Creatine Kinase