Generating large mechanical power during actions such as sprinting or jumping is a crucial factor in many sports. These types of actions require a good warm-up activation. Capacitive-Resistive Electric Transfer (CRET) is a non-invasive therapy based on the application of radio frequency electric currents within the range of 300 kHz-1.2 MHz to accelerate tissue metabolic activity. This study aimed to evaluate the effectiveness of adding CRET to an active warm-up protocol in young adult athletes. For the double-blind randomized clinical trial, 60 healthy athletes were recruited and divided into an Experimental group (EG) and a Sham group (SG). EG received a CRET protocol in addition to an active warm-up. SG carried out the same warm-up but with a placebo CRET. The main outcome measures were isometric extension force, countermovement-jump (CMJ), 30 m-sprint test, and surface electromyography (sEMG). There is no statistically significant interaction (group-time) for any of the variables studied. Significant main effects for time were found in isometric extension force (p = 0.008); 30 m sprint (p = 0.017); rectus femoris sEMG during CMJ (p = 0.002); vastus lateralis sEMG during CMJ (p = 0.012); vastus medialis during CMJ (p = 0.010) and rectus femoris sEMG during the 30 m sprint test (p = 0.012). Non-significant differences between means are observed in the isometric extension force (48.91 EG; 10.87 SG) and 30 m sprint (-0.13 EG; -0.04 SG) variables. To conclude, a non-significant tendency was observed in sprint and quadriceps strength following CRET therapy, compared to the individuals' pre-treatment state. Future research should use more treatment sessions to observe this tendency.
Keywords: CRET therapy; muscle activity; sprint.