Effect of pre-exercise phototherapy applied with different cluster probe sizes on elbow flexor muscle fatigue.
Phototherapy has been used for reducing muscle fatigue. In view of the various types of phototherapy cluster probes available in the market, the purpose of this study was to compare the effects of a similar phototherapy dosage with two different cluster probes on elbow flexor muscle fatigue: small cluster probe (SC = 9 diodes; 7.5 cm(2)) vs. large cluster probe (LC = 33 diodes; 30.2 cm(2)). Ten physically active male aged 18-35 years participate in a randomized, crossover, double-blind, placebo-controlled trial, which each participant was submitted to the same testing protocol in four sessions (separated by at least 48 h) with different treatments: LC-phototherapy, SC-phototherapy, LC-placebo, and SC-placebo. The elbow flexion maximal isometric voluntary contraction (MIVC) was performed before and after a fatigue protocol (60 % of MIVC until exhaustion). Electromyography (EMG) of the biceps brachii muscle was collected during all testing procedure. Phototherapy with dose of 60 J per muscle [LC: 33 diodes = 5 lasers (850 nm), 12 LEDs (670 nm), 8 LEDs (880 nm), and 8 LEDs (950 nm); SC: 9 diodes = 5 lasers (850 nm) and 4 LEDs (670 nm)] or placebo applications occurred before fatigue protocol. Two-way ANOVA (treatment and time factors) and one-way ANOVA were used, followed by LSD post hoc. Time to exhaustion was significantly higher in active LC (15 %; p = 0.031) and SC (14 %; p = 0.038) in comparison with their respective placebo treatments, without differences between LC and SC (p > 0.05) or between placebo conditions (p > 0.05). This larger exercise tolerance in phototherapy conditions was not accompanied by a higher decrement in the volunteers' maximal strength capacity (11-15 %; p > 0.05 for all). EMG signals presented no difference between the four condition tested here. In both large and small cluster probes (according parameters tested in this study) led to reduced fatigue in elbow flexor muscles, without difference between them.
Biomechanics Laboratory, Federal University of Santa Catarina, Florianópolis, SC, Brazil.|Human Performance Laboratory, Physical Education Faculty, Federal University of Amazonas, Manaus, AM, Brazil.
Mateus
M
Rossato
Biomechanics Laboratory, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
Rodolfo A
RA
Dellagrana
Exercise Research Laboratory, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.|Regional University of Alto Uruguai e das Missões, Santo Ângelo, RS, Brazil.
Fábio J
FJ
Lanferdini
Biomechanics Laboratory, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
Raphael L
RL
Sakugawa
Biomechanics Laboratory, Federal University of Santa Catarina, Florianópolis, SC, Brazil.
Caetano D
CD
Lazzari
Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil.
Bruno M
BM
Baroni
Biomechanics Laboratory, Federal University of Santa Catarina, Florianópolis, SC, Brazil. fernando.diefenthaeler@ufsc.br.
Fernando
F
Diefenthaeler
D000293:Adolescent; D000328:Adult; D001132:Arm; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004550:Elbow; D004576:Electromyography; D017079:Exercise Tolerance; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology* / Q000528:radiation effects*; D010789:Phototherapy / Q000379:methods*; D016059:Range of Motion, Articular; D055815:Young Adult
Ergogenic effect and electromyography; Light-emitting diodes therapy; Low-level laser therapy; Neuromuscular economy