Effects of pre- or post-exercise low-level laser therapy (830 nm) on skeletal muscle fatigue and biochemical markers of recovery in humans: double-blind placebo-controlled trial.
OBJECTIVE
The purpose of this study was to investigate the effect of low-level laser therapy (LLLT) before and after exercise on quadriceps muscle performance, and to evaluate the changes in serum lactate and creatine kinase (CK) levels.


METHODS
The study was randomized, double blind, and placebo controlled.


METHODS
A sample of 27 healthy volunteers (male soccer players) were divided into three groups: placebo, pre-fatigue laser, and post-fatigue laser. The experiment was performed in two sessions, with a 1 week interval between them. Subjects performed two sessions of stretching followed by blood collection (measurement of lactate and CK) at baseline and after fatigue of the quadriceps by leg extension. LLLT was applied to the femoral quadriceps muscle using an infrared laser device (830 nm), 0.0028 cm(2) beam area, six 60 mW diodes, energy of 0.6 J per diode (total energy to each limb 25.2 J (50.4 J total), energy density 214.28 J/cm(2), 21.42 W/cm(2) power density, 70 sec per leg. We measured the time to fatigue and number and maximum load (RM) of repetitions tolerated. Number of repetitions and time until fatigue were primary outcomes, secondary outcomes included serum lactate levels (measured before and 5, 10, and 15 min after exercise), and CK levels (measured before and 5 min after exercise).


RESULTS
The number of repetitions (p=0.8965), RM (p=0.9915), and duration of fatigue (p=0.8424) were similar among the groups. Post-fatigue laser treatment significantly decreased the serum lactate concentration relative to placebo treatment (p<0.01) and also within the group over time (after 5 min vs. after 10 and 15 min, p<0.05 both). The CK level was lower in the post-fatigue laser group (p<0.01).


CONCLUSIONS
Laser application either before or after fatigue reduced the post-fatigue concentrations of serum lactate and CK. The results were more pronounced in the post-fatigue laser group.
1 Department of Physiotherapy, University Anhanguera-Uniderp , Campo Grande, MS, Brazil .
Filipe Abdalla
FA
Dos Reis
Baldomero Antonio Kato
BA
da Silva
Erica Martinho Salvador
EM
Laraia
Rhaiza Marques
RM
de Melo
Patrícia Henrique
PH
Silva
Ernesto Cesar Pinto
EC
Leal-Junior
Paulo de Tarso Camillo
Pde T
de Carvalho
D000293:Adolescent; D000328:Adult; D003404:Creatinine / Q000097:blood; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D028022:Low-Level Light Therapy; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology* / Q000528:radiation effects*; D052097:Quadriceps Muscle / Q000503:physiopathology* / Q000528:radiation effects; D055815:Young Adult
D019344:Lactic Acid; D003404:Creatinine