Effects of 808 nm low-power laser irradiation on the muscle contraction of frog gastrocnemius

Background and objectives The efficacy of low‐power laser irradiation (LLI) on muscle fibers remains unclear; therefore, we examined the effect of LLI (808 nm: 60 or 100 mW) on muscle contraction and conducted waveform analyses of the twitch curve, including alterations in the peak amplitudes of tension (AMP), latency (LAT), contraction period (CP), and relaxation period (RP). Study design/materials and methods The sciatic nerve‐gastrocnemius muscles of 35 frogs (Xenopus laevis) were prepared. In Experiment 1, continuous stimulation for gastrocnemius contraction was delivered to the sciatic nerve (10 minutes); the experimental group simultaneously received LLI. In Experiment 2, two sets of stimulation and cessation (2 minutes each) were repeated after the initial stimulation period (2 minutes); the experimental group received LLI during the resting period. Results and conclusions In Experiment 1, 60 mW LLI significantly facilitated an attenuation of AMP and maintained a smaller prolongation of CP (P