Low-level Laser Therapy Improves Recovery after Exhausting Exercise induced Fatigue: A Randomized, Double-blind and Placebo Controlled Cross-over Study / 中国运动医学杂志

ABSTRACT

Objective To explore the effect of low-level laser therapy (LLLT)applied to the quadriceps muscle on the recovery of exhausting-cycling-exercise-induced fatigue.Methods According to a randomised,double-blind and crossover design,16 healthy male students were randomly assigned to an LLLT-1,LLLT-3,LLLT-5 and a placebo group,and received LLLT for 300 s at the dosage of 0.06 J· cm-2,0.18 J·cm-2,0.3 J·cm-2 and 0 to the bilateral rectus femoris after the exhausting-cycling-exercise-induced fatigue.The blood lactate(BL),heart rate(HR),rated perceived exertion(RPE)and visual analogue scale(VAS)were assessed before the exercise,immediately after exercise,10 and 20 min after exercise,as well as immediately after the first Wingate(WG)test,5 and 30 min after the WG test.Meanwhile,the second WG test was performed 40 min after the first WG test.Results The average HR value of LLLT-1 group was significantly lower than the placebo group at 10 min after exercise(P＜ 0.05)and immediately after the WG test(P＜0.01),while that of LLLT-3 and LLLT-5 groups was significantly lower than the placebo group immediately and 5 min after the WG test(P＜0.01).Compared to the placebo group,the average BL of LLLT-1,LLLT-3 and LLLT-5 groups was significantly lower 10 min after exercise(P＜0.05 for all)and that of LLLT-5 group was also significantly lower 30 min after the first WG test(P＜0.05).However,the average blood glucose of LLLT-5 group was significantly higher than the placebo group right after the first WG test(P＜0.05).Moreover,significant increase was observed in the mean(P=0.002)and peak power(P=0.006)at the second WG test and the mean(P=0.048) power at the first WG test of LLLT-3 group,compared to the placebo group.Conclusion LLLT applied to quadriceps muscles after exhausting exercise may enhance recovery,and LLLT at the dose of 0.18 J·cm-2 is of the best effect.