Yanying Liu#, Haiping Yang


Department of Physical Education and Health, Zhaoqing University, Zhaoqing 526000, (China)


Objective: The purpose of this study was to investigate the effects of low-level laser therapy (LLLT) on skeletal muscle performance and fatigue development.

Methods: A randomized, double-blind placebo-controlled trial was conducted with the participation of 16 swimming athletes recruited from male college students. LLLT was applied before the exercise with He-Ne laser, 632.8 nm, output power of 50 mW, 300 s total irradiation time and energy density of 3 J/cm2 per point or placebo at two sites of the bilateral rectus femoris. 200-m breaststroke swimming performance, blood lactate levels, heart rate and rated perceived exertion (RPE) were measured before and immediately after all-out sprint of 200-m breaststroke swimming, respectively.

Results: The 200-m breaststroke swimming performance were significantly enhanced by LLLT (p <0.05) compared to the placebo group. However, blood lactate levels and heart rate were significantly decreased (p <0.05), the RPE has no significant change (p >0.05).

Conclusion: Laser application before exercise delayed the development of muscle fatigue, enhanced the 200-m breaststroke swimming performance, decreased blood lactate level and heart rate.


LLLT, performance, fatigue, lactate.