Photobiomodulation therapy for muscle damage and fatigue following electrical stimulation - a controlled trial

A single session of low level laser therapy (LLLT) irradiations, of an approximate duration of 18 minutes, provided by a physiotherapist, in six skin areas (25 cm2 each, with direct contact of the probe to skin, with slight pressure), i.e. 5 cm above the middle of the line connecting the anterior superior iliac spine and the base of patella and 5 cm below that spot, in two areas above the vastus medialis muscle belly, and in two areas above the vastus lateralis muscle belly. The dose of 30 J (preventing from the thermal effects to occur) applied in each area (i. e the overall dose of 180 J), with a cluster probe consisting of four semiconducting lasers, 830 nm, of 200 mW each, using BTL 5000 device (BTL Industries Limited, London). The LLLT, or sham LLLT, session was followed by a NMES session, provided by a physiotherapist. It consisted of forty five electrically evoked tetanic, isometric contractions, in the 5 sec. ON, 15 sec. OFF mode, with 1.5 sec. ramp-on and 0.5 sec. ramp-off times (15 minutes overall time of the NMES session). NMES was performed with the use of a stationary electrical stimulator Sonicator Plus 940 (Mettler Electronics Corporation, USA), generating pulsed, two-phase, 300 µs, square-wave, symmetrical, delivered at 80 Hz, current. Four (two electric circuits) round, self-adhesive, 5 cm diameter electrodes were placed over motor points, on previously rinsed with alcohol and dried skin The current intensity was set at the level of tolerance (below pain threshold) and adjusted by the physiotherapist to that level when needed during the session. There are no strategies used to assess or monitor fidelity to this study. At the first stage of this crossover study, group 1 (n=12) received NMES and LLLT, while group 2 (n=12) received NMES and sham LLLT. A reverse procedure was applied after an eight-day wash-out period, sufficient to eliminate the carryover effect.