Effects of GaAs laser and stretching on muscle contusion in rats

Daniela Gallon Corrêa,Anna Raquel Silveira Gomes,Juliana T Okita,Hilana Rickli Fiuza Martins

doi:10.1590/1809-2950/13903823012016

Daniela Gallon Corrêa, Anna Raquel Silveira Gomes + Show 2 more

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https://doi.org/10.1590/1809-2950/13903823012016

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Abstract

ABSTRACT Laser 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.

Highlights

The most common skeletal muscle injury in contact sports is contusion[1]
The animals were randomly divided into six groups: 1) Control group (CG, n=6): animals were kept intact during 4 weeks; 2) Lesion group (LG) (n=6): rats were submitted to the left tibialis anterior (TA) muscle contusion with an apparatus as described by Minamoto et al.[22] and kept at the vivarium for 4 weeks22,23; 3) Lesion and laser group (LLG, n=6): the left TA underwent contusion and the treatment was started 48 hours later with Gallium Arsenide (GaAs) Laser
In the group subjected only to stretching we did not observe any difference in the cross sectional area of muscle fibers (CSAMF), but we found a decrease in the percentage of connective tissue when compared to the group injured and treated with laser and stretching

Summary

Introduction

The most common skeletal muscle injury in contact sports is contusion[1]. Different physiotherapeutic intervention techniques are used to accelerate the muscle repair process and reestablish function, such as: cryotherapy[2]; therapeutic ultrasound[3]; laser[4]; and early mobilization and exercises[5]. The skeletal muscle adaptations to these techniques are not entirely elucidated[5]. Studies have shown that muscle regeneration, in vivo as well as in vitro, becomes more effective when treated with low intensity laser[6,7]. It has been demonstrated[8,9] that lasers operating at different wavelengths activate the macrophages to release factors that stimulate fibroblast proliferation. Low-intensity laser acts on the synthesis and collagen remodeling, fibroblast number, diameter, and tensile strength of the treated wounds[7]

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