Muscle

Rennó AC, Toma RL, Feitosa SM, Fernandes K, Bossini PS, de Oliveira P, Parizotto N, Ribeiro DA.
Department of Medical Biophysics, Pavol Jozef Šafárik University, Košice, Slovak Republic.

Photomed Laser Surg. 2011 Jan;29(1):5-10. Epub 2010 Dec 18. [PMID: 21166589]

Abstract

Objective: The main purpose of this study was to compare the effects of low-intensity pulsed ultrasound (US) and low-level laser therapy (LLLT) on injured skeletal muscle after cryolesion by means of histopathological analysis and immunohistochemistry for cyclo-oxygenase-2 (COX-2).

Background and methods: Thirty-five male Wistar rats were randomly distributed into four groups: intact control group with uninjured and untreated animals; injured control group with muscle injury and no treatment; LLLT-treated group with muscle injury treated with 830-nm laser; and US-treated group with muscle injury treated with US. Treatments started 24 h postsurgery and were performed during six sessions.

Results: LLLT-treated animals presented minor degenerative changes of muscle tissue. Exposure to US reduced tissue injuries induced by cryolesion, but less effectively than LLLT. A large number of COX-2 positive cells were found in untreated injured rats, whereas COX-2 immunoexpression was lower in both LLLT- and US-treated groups.

Conclusion: This study revealed that both LLLT and US therapies have positive effects on muscle metabolism after an injury in rats, but LLLT seems to produce a better response.

Leal Junior EC, Lopes-Martins RA, Baroni BM, De Marchi T, Taufer D, Manfro DS, Rech M, Danna V, Grosselli D, Generosi RA, Marcos RL, Ramos L, Bjordal JM.
Sports Medicine Institute (IME), University of Caxias do Sul (UCS), Caxias do Sul, RS, Brazil. ecplealj@ucs.br

Lasers Med Sci. 2009 Nov;24(6):857-63. Epub 2008 Dec 5. [PMID: 19057981]

Abstract

Our aim was to investigate the immediate effects of bilateral, 830 nm, low-level laser therapy (LLLT) on high-intensity exercise and biochemical markers of skeletal muscle recovery, in a randomised, double-blind, placebo-controlled, crossover trial set in a sports physiotherapy clinic. Twenty male athletes (nine professional volleyball players and eleven adolescent soccer players) participated. Active LLLT (830 nm wavelength, 100 mW, spot size 0.0028 cm(2), 3-4 J per point) or an identical placebo LLLT was delivered to five points in the rectus femoris muscle (bilaterally). The main outcome measures were the work performed in the Wingate test: 30 s of maximum cycling with a load of 7.5% of body weight, and the measurement of blood lactate (BL) and creatine kinase (CK) levels before and after exercise. There was no significant difference in the work performed during the Wingate test (P > 0.05) between subjects given active LLLT and those given placebo LLLT. For volleyball athletes, the change in CK levels from before to after the exercise test was significantly lower (P = 0.0133) for those given active LLLT (2.52 U l(-1) +/- 7.04 U l(-1)) than for those given placebo LLLT (28.49 U l(-1) +/- 22.62 U l(-1)). For the soccer athletes, the change in blood lactate levels from before exercise to 15 min after exercise was significantly lower (P < 0.01) in the group subjected to active LLLT (8.55 mmol l(-1) +/- 2.14 mmol l(-1)) than in the group subjected to placebo LLLT (10.52 mmol l(-1) +/- 1.82 mmol l(-1)). LLLT irradiation before the Wingate test seemed to inhibit an expected post-exercise increase in CK level and to accelerate post-exercise lactate removal without affecting test performance. These findings suggest that LLLT may be of benefit in accelerating post-exercise recovery.

Nakano, Jiro; Kataoka, Hideki; Sakamoto, Jyunya; Origuchi, Tomoki; Okita, Minoru; Yoshimura, Toshiro
Unit of physical therapy and occupational therapy sciences, Nagasaki University Graduate School of Biomedical Sciences. Department of Rehabilitation, Nagasaki Memorial Hospital

Experimental Physiology, 94(9), pp.1005-1015; 2009 [PMID: 21166589]

Abstract

Low-level laser (LLL) irradiation promotes proliferation of muscle satellite cells, angiogenesis and expression of growth factors. Satellite cells, angiogenesis and growth factors play important roles in the regeneration of muscle. The objective of this study was to examine the effect of LLL irradiation on rat gastrocnemius muscle recovering from disuse muscle atrophy. Eight-week-old rats were subjected to hindlimb suspension for 2 weeks, after which they were released and recovered. During the recovery period, rats underwent daily LLL irradiation (Ga-Al-As laser; 830 nm; 60 mW; total, 180 s) to the right gastrocnemius muscle through the skin. The untreated left gastrocnemius muscle served as the control. In conjunction with LLL irradiation, 5-bromo-2-deoxyuridine (BrdU) was injected subcutaneously to label the nuclei of proliferating cells. After 2 weeks, myofibre diameters of irradiated muscle increased in comparison with those of untreated muscle, but did not recover back to normal levels. Additionally, in the superficial region of the irradiated muscle, the number of capillaries and fibroblast growth factor levels exhibited significant elevation relative to those of untreated muscle. In the deep region of irradiated muscle, BrdU-positive nuclei of satellite cells and/or myofibres increased significantly relative to those of the untreated muscle. The results of this study suggest that LLL irradiation can promote recovery from disuse muscle atrophy in association with proliferation of satellite cells and angiogenesis.

Yasushi Ishide, Toshio Ohshiro, Fumio Ueda, Mitsuyoshi Murayama, Takafumi Ohshiro, Kiyofumi Takenouchi, and Mitsuaki Kohzuma
Keio University Institute of Physical Education. Japan Medical Laser Laboratory. Ohshiro Clinic

JSTAGE(Received October 5, 2009) (Accepted January 21, 2010)

Abstract

Low reactive-level laser therapy (LLLT) has been reported to reduce chronic and acute pain. Recently, some studies have shown that LLLT may also delay skeletal muscle fatigue during high-intensity exercise. We have hypothesized that laser irradiation may also attenuate muscle fatigue or pain experienced after sports or exercise. However, only a few reports have described the use of lasers in sports medicine. This study was conducted to determine the effectiveness of LLLT in aiding the recovery from exercise-induced skeletal muscle fatigue. Subjects and Methods: Isometric plantar flexion was repeatedly performed on 9 students until the force output declined to 50% maximal voluntary contraction (MVC). Subjects were assigned to perform 3 experiments under different LLLT conditions: laser irradiation to the neck (NKL), to the muscle (MSL), and no laser irradiation (CON). MVC and muscle hardness, girth, blood oxygen saturation, and heart rate were measured during the pre-exercise, post-exercise, and recovery phases. The neck and muscle were irradiated for 15 s using the Oh-Lase HT 2001 semi-conductor laser (830 nm; 60 mW, continuous wave), immediately after MVC measurement during the post-exercise phase.Results: The total exercise time and mean output forces were analyzed using repeated-measures and one-factor ANOVA with post-hoc tests; no significant differences were observed among the 3 conditions for the pre and post-exercise MVC levels before irradiation (NKL, 68.1% MVC; MSL, 66.4% MVC; CON, 66.1% MVC). However, the MVC at 5 and 10 min after exercise was significantly greater in the NKL and MSL groups than in the CON group (MVC after 5 min: 80.4%, 76.9%, and 69.7% for the NKL, MSL, and CON groups, respectively; MVC after 10 min: 81.8%, 81.2%, and 74.4%). Further, no significant differences were observed in the MVC recorded at 15 and 30 min. Therefore, compared to the CON group, the NKL and MSL groups exhibited early muscle-strength recovery from fatigue caused by repeated contractions.Conclusion: We concluded that LLLT at the parameters used in the present study effectively promoted the recovery of the isometric force output after muscle fatigue induced by repeated contractions, especially in the acute-exhaustion phase.