Strength training prior to muscle injury potentiates low-level laser therapy (LLLT)-induced muscle regeneration

Abstract

We evaluated whether strength training (ST) performed prior to skeletal muscle cryolesion would act as a preconditioning, improving skeletal muscle regeneration and responsiveness to low-level laser therapy (LLLT). Wistar rats were randomly assigned into non-exercised (NE), NE plus muscle lesion (NE + LE), NE + LE plus LLLT (NE + LE + LLLT), strength training (ST), ST + LE, and ST + LE + LLLT. The animals performed 10 weeks of ST (climbing ladder; 3× week; 80% overload). Forty-eight hours after the last ST session, tibialis anterior (TA) cryolesion was induced and LLLT (InGaAlP, 660 nm, 0.035 W, 4.9 J/cm/point, 3 points, spot light 0.028 cm, 14 J/cm) initiated and conducted daily for 14 consecutive days. The difference between intergroups was assessed using Student's t test and intragroups by two-way analysis of variance. Cryolesion induced massive muscle degeneration associated with inflammatory infiltrate. Prior ST improved skeletal regeneration 14-days after cryolesion and potentiated the regenerative response to LLLT. Cryolesion induced increased TNF-α levels in both NE + LE and ST + LE groups. Both isolated ST and LLLT reduced TNF-α to control group levels; however, prior ST potentiated LLLT response. Both isolated ST and LLLT increased IL-10 levels with no additional effect. In contrast, increased TA IL-6 levels were restricted to ST and ST + LE + LLLT groups. TA myogenin mRNA levels were not changed by neither prior ST or ST + LLLT. Both prior ST and LLLT therapies increased MyoD mRNA levels and, interestingly, combined therapies potentiated this response. Myf5 mRNA levels were increased only in ST groups. Taken together, our data provides evidences for prior ST potentiating LLLT efficacy in promoting skeletal muscle regeneration.

Low-level laser therapy (LLLT) accelerates the sternomastoid muscle regeneration process after myonecrosis due to bupivacaine

“…Similar results were also observed after six days of LLLT applications after cryoinjury [42]. Even after 4 days of cryolesion and LLLT therapy [71] and after 14 days [72] a decrease in muscle levels of TNF-α was found. Pires et al [73] studied tendinitis in rats after 7 and 14 days and they showed that LLLT reduced the TNF-α expression only at chronic phase.…”

Effects of strength training on osteogenic differentiation and bone strength in aging female Wistar rats

“…Furthermore, it is likely that the expression of growth factors and the increase of bone matrix production favored osteogenesis, consequently improving bone structural and mechanical properties in exercised aged animals. We believe that these findings reflect the intensity of the ST program, i.e., using low repetition/high overload 3 13 14 , in which aged rats displayed a MVCC value, expressed as relative value to the body weight, of 128.81% in comparison to the values obtained previous to ST program practice ( Table 1 ). In addition, it is important to consider that the length of the training period (16 weeks) contributed to the significant differences observed in biomechanical properties.…”

Therapeutic efficacy of early photobiomodulation therapy on the zones of stasis in burns: An experimental rat model study

“…Photobiomodulation therapy has been shown to relieve or treat many diseases, such as refractory wounds, skin ulcers, and skin flap transplant wounds . This modality uses therapeutic light wavelengths of 600–700 nm, which are perceived as red light by the human retina, to induce photochemical reactions at the irradiation site and thus promote cell proliferation and reduce apoptosis and necrosis to improve prognosis. Accordingly, photobiomodulation therapy may be beneficial to the healing of burn wounds if used to improve the prognosis of the zone of stasis and thus prevent increases in burn depth.…”