Effects of cathode and anode of the direct current on changes in palmar grip strength: assessment through a dynamometry

ABSTRACT This study objective is to investigate the polar effects of the direct current on muscular strength, evaluated by the manual dynamometer. The values of muscle strength, in kilograms, were compared before and after the procedure in the 3 groups (Anode, Cathode and Control). The project is a controlled randomized clinical trial, which was performed at the Laboratory of Physiotherapy of the University Andrés Bello (Physioterpy Carrer) with 150 healthy voluntary participants. The intervention consisted on the application of a direct current session with intensity of 2mA for 12 minutes, with an electrode of 48cm2 (dose of 24mA×min and current density of 0.04mA/cm2). The difference between the groups was in the stimulus with the cathode or the anode, and the application of the current was performed after the initial dynamometric evaluation. The main measured variable was the difference of maximum force of palmar grip (Kg), which was obtained through the difference between the best value of maximum pre-intervention force and the best value of maximum post-intervention force. The results indicate that there were no statistically significant changes in the intervention groups (p value=0.88) when comparing the maximum strength differences (FMdif). However, a slight improvement in strength was observed when comparing the groups only considering men from the cathode group (p value=0.94), and a slight decrease when comparing only women from the anode group (p value=0.91). It was concluded that, apparently, the direct current would not generate greater changes in the force of manual grasp after an intervention session on the forearm. Nevertheless, there are positive variations of strength in men from the cathode group, and negative ones in women from the anode group when analyzed independently, although these modifications are not statistically significant.