Effects of low-level laser therapy (LLLT) in the development of exercise-induced skeletal muscle fatigue and changes in biochemical markers related to postexercise recovery.
METHODS
Randomized crossover double-blinded placebo-controlled trial.


OBJECTIVE
To investigate if low-level laser therapy (LLLT) can affect biceps muscle performance, fatigue development, and biochemical markers of postexercise recovery.


BACKGROUND
Cell and animal studies have suggested that LLLT can reduce oxidative stress and inflammatory responses in muscle tissue. But it remains uncertain whether these findings can translate into humans in sport and exercise situations.


METHODS
Nine healthy male volleyball players participated in the study. They received either active LLLT (cluster probe with 5 laser diodes; lambda = 810 nm; 200 mW power output; 30 seconds of irradiation, applied in 2 locations over the biceps of the nondominant arm; 60 J of total energy) or placebo LLLT using an identical cluster probe. The intervention or placebo were applied 3 minutes before the performance of exercise. All subjects performed voluntary elbow flexion repetitions with a workload of 75% of their maximal voluntary contraction force until exhaustion.


RESULTS
Active LLLT increased the number of repetitions by 14.5% (mean +/- SD, 39.6 +/- 4.3 versus 34.6 +/- 5.6; P = .037) and the elapsed time before exhaustion by 8.0% (P = .034), when compared to the placebo treatment. The biochemical markers also indicated that recovery may be positively affected by LLLT, as indicated by postexercise blood lactate levels (P<.01), creatine kinase activity (P = .017), and C-reactive protein levels (P = .047), showing a faster recovery with LLLT application prior to the exercise.


CONCLUSIONS
We conclude that pre-exercise irradiation of the biceps with an LLLT dose of 6 J per application location, applied in 2 locations, increased endurance for repeated elbow flexion against resistance and decreased postexercise levels of blood lactate, creatine kinase, and C-reactiveprotein.


METHODS
Performance enhancement, level 1b.
Leal Junior
Ernesto Cesar Pinto
EC
Center for Research and Innovation in Laser, Nove de Julho University (UNINOVE), São Paulo, SP, Brazil. ernesto.leal.junior@gmail.com
Lopes-Martins
Rodrigo Alvaro Brandão
RA
Frigo
Lucio
L
De Marchi
Thiago
T
Rossi
Rafael Paolo
RP
de Godoi
Vanessa
V
Tomazoni
Shaiane Silva
SS
Silva
Daniela Perin
DP
Basso
Maira
M
Filho
Pedro Lotti
PL
de Valls Corsetti
Francisco
F
Iversen
Vegard V
VV
Bjordal
Jan Magnus
JM
D000293:Adolescent; D001132:Arm; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D003402:Creatine Kinase / Q000097:blood; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D028022:Low-Level Light Therapy; D008297:Male; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000528:radiation effects*; D005082:Physical Exertion; D020127:Recovery of Function; D055815:Young Adult
D015415:Biomarkers; D019344:Lactic Acid; D002097:C-Reactive Protein; D003402:Creatine Kinase