Effect Of High-intensity Laser Therapy Before Exercise On Blood Lactate Production After Exercise

PURPOSE: The increase of blood lactate can lead to muscle fatigue and affect exercise performance. High-intensity laser has been proved its effectiveness in relieving pain and improving peripheral nerve function, but its effectiveness in reducing blood lactate is still unknown. This study aims to explore whether high-intensity laser intervention could reduce blood lactate production after exercise. METHODS: Twenty college students were recruited and randomly assigned to high-intensity laser irradiation group (age 23.7 ± 1.34 years,body weight 74.7 ± 7.56 kg,height 178.1 ± 7.97 cm)or sham-laser group(age 23.7 ± 0.82 years,body weight 76.1 ± 8.43 kg,height 178.1 ± 3.38 cm). After the intervention, the Wingate test was performed. The laser wavelength was mixed at 810 nm and 980 nm, and the power was 15 W. Blood lactic acid was measured at 5 min and 10 min after exercise before and after intervention.Two-way ANOVA with repeated measures was used to analyze data. RESULTS: Significant group-by-intervention interaction were detected in 5 min(p = 0.026,n2p = 0.481).Post hoc analysis showed that average change values of blood lactic acid reduce in the high-intensity laser group(before intervention = 19.94 ± 1.97,after intervention = 16.04 ± 3.33,p = 0.001,d = 1.42)while remained unchanged in the sham-laser group(before intervention = 20.09 ± 1.74,after intervention = 18.92 ± 2.06,p = 0.138,d = 0.61).However, there was no significant difference in blood lactate at 10 min post-exercise between the two groups before and after the intervention. CONCLUSIONS: The use of high-intensity laser therapy before exercise in college students can reduce the production of blood lactic acid after exercise in 5 min, but there was no reduction observed in 10 min.High-intensity laser can reduce the blood lactic acid level immediately after exercise.