Effect of 655-nm Low-Level Laser Therapy on Exercise-Induced Skeletal Muscle Fatigue in Humans

Author(s)

Pinto Leal, Jr., Ernesto Cesar ^{[1, 2]} ; Lopes-Martins, Rodrigo Alvaro Brandao ^[3] ; Dalan, Francis ^[4] ; Ferrari, Mauricio ^[4] ; Sbabo, Fernando Montanari ^[4] ; Generosi, Rafael Abeche ^[5] ; Baroni, Bruno Manfredini ^[4] ; Penna, Socrates Calvoso ^[3] ; Iversen, Vegard V. ^[6] ; Bjordal, Jan Magnus ^{[1, 7]}

Affiliation

^[1] Univ Bergen, Sect Physiotherapy Sci, Inst Publ Hlth & Primary Hlth Care, Bergen - Norway

^[2] Univ Caxias do Sul, Lab Human Movement, Sports Med Inst, BR-95070560 Caxias Do Sul, RS - Brazil

^[3] Univ Sao Paulo, Lab Pharmacol & Phototherapy Inflammat, Dept Pharmacol, Inst Biomed Sci, Sao Paulo - Brazil

^[4] Univ Caxias do Sul, Fac Physiotherapy, BR-95070560 Caxias Do Sul, RS - Brazil

^[5] Univ Caxias do Sul, Fac Phys Educ, BR-95070560 Caxias Do Sul, RS - Brazil

^[6] Univ Bergen, Inst Biomed, Physiol Sect, Bergen - Norway

^[7] Bergen Univ Coll, Inst Phys Therapy, Bergen - Norway

• Document type: Journal article
• Source: Photomedicine and Laser Surgery; v. 26, n. 5, p. 419-424, OCT 2008.
• Web of Science Citations: 90

Abstract

Objective: To investigate if development of skeletal muscle fatigue during repeated voluntary biceps contractions could be attenuated by low-level laser therapy (LLLT). Background Data: Previous animal studies have indicated that LLLT can reduce oxidative stress and delay the onset of skeletal muscle fatigue. Materials and Methods: Twelve male professional volleyball players were entered into a randomized double-blind placebo-controlled trial, for two sessions (on day 1 and day 8) at a 1-wk interval, with both groups performing as many voluntary biceps contractions as possible, with a load of 75% of the maximal voluntary contraction force (MVC). At the second session on day 8, the groups were either given LLLT (655 nm) of 5 J at an energy density of 500 J/cm(2) administered at each of four points along the middle of the biceps muscle belly, or placebo LLLT in the same manner immediately before the exercise session. The number of muscle contractions with 75% of MVC was counted by a blinded observer and blood lactate concentration was measured. Results: Compared to the first session (on day 1), the mean number of repetitions increased significantly by 8.5 repetitions (+/- 1.9) in the active LLLT group at the second session (on day 8), while in the placebo LLLT group the increase was only 2.7 repetitions (+/- 2.9) (p = 0.0001). At the second session, blood lactate levels increased from a pre-exercise mean of 2.4 mmol/L (+/- 0.5 mmol/L), to 3.6 mmol/L (+/- 0.5 mmol/L) in the placebo group, and to 3.8 mmol/L (+/- 0.4 mmol/L) in the active LLLT group after exercise, but this difference between groups was not statistically significant. Conclusion: We conclude that LLLT appears to delay the onset of muscle fatigue and exhaustion by a local mechanism in spite of increased blood lactate levels. (AU)

• FAPESP's process: 05/02117-6 - Effect of therapies of inhaled nitric oxide and low power laser on the experimental model fo tendonitis induced by collagenase in rats
• Grantee: Rodrigo Alvaro Brandão Lopes Martins
• Support Opportunities: Regular Research Grants