Effects of GaAs laser and stretching on muscle contusion in ratsLaser and stretching are used to treat skeletal muscle injuries. This study aimed to evaluate the effects of GaAs laser and stretching in the morphology of the tibialis anterior (TA) muscle after contusion. Thirty-six male rats (349±23g) were divided into six groups (n=6): control group (CG); lesion group (LG); lesion and laser group (LLG); lesion and stretching group (LSG); lesion, laser and stretching group (LLSG); and stretching group (SG). TA was wounded by a contusion apparatus. We used GaAs laser 4.5 J/cm2 dose for 32 s each, beginning 48 h after lesion, for 7 days, once a day. Manual passive stretching was applied by 10 repetitions for 1 minute, initiating on the 8th day, once a day, 3 times a week, during 3 weeks. After 4 weeks, rats were euthanized and we analyzed: muscle weight and length, cross sectional area of muscle fibers (CSAMF), serial sarcomere number (SSN), sarcomere length, and percentage of connective tissue. Comparisons among groups were made by ANOVA and post hoc Tukey tests, with the significance level set at ≤ 0.05. The serial sarcomere number of LLSG was higher than LSG. The sarcomere length of LSG was superior to LLG, LLSG, and SG. SG increased SSN compared to CG, while the percentage of connective tissue of SG decreased in comparison to LLSG. Thus, the sarcomerogenesis of injured muscles was enhanced by laser therapy, stretching, and association of both. The stretching protocol was enough to increase SSN of intact muscles.
Keywords:
Skeletal Muscle; Muscle Stretching Exercises; Wounds and Injuries; Low-Level Light Therapy; Rats
A: Final Body weight: p= 0.02 (ANOVA) when compared to LG and LSG; B: Muscle Weight: §p=0.003 (ANOVA) when compared to SG. C: Cross Sectional Area of Muscle fibers (CSAMF); D: Connective Tissue Percentage: *p=0.004 (ANOVA) in comparison with LLSG. The results are mean±standard deviation. Control Group (CG); Lesion Group (LG); Lesion and Laser group (LLG); Lesion and Stretching Group (LSG); Lesion, Laser and Stretching Group (LLSG); Stretching Group (SG)
A: Serial sarcomere number, ■when compared to LSG (p= 0.002); SG (p=0.004) and LLSG (p=0.004); ●p=0.005 compared to LSG (p=0.02); to LG (p= 0.00003); to LLG (p= 0.0004); to LLSG (p=0.001); to LSG (p=0.02) and to SG (p=0.001). B: Muscle Length, †when compared to SG (p=0.003) and LSG (p=0.008); ♦ when compared to LLSG (p=0.04) and SG (p=0.01); *p=0.00002 (LG); p=0.00006 (LLG); p= 0.001(LSG); p= 0.00003 (LLSG) and p=0.0003 (SG) when compared to CG. C: Sarcomere Length, §p=0.04 (CG and LG) when compared to LSG, ‡p=0.0006 (LLSG) compared to CG; #p=0.001 (LSG) and p=0.03 (LLSG) when compared to LLG; =0.03 (LSG) and p=0.02 (LLSG) when compared to SG. The results are mean±standard deviation. Control Group (CG); Lesion Group (LG); Lesion and Laser group (LLG); Lesion and Stretching Group (LSG); Lesion, Laser and Stretching Group (LLSG); Stretching Group (SG). mm: millimeter;μm: micrometer