Introduction:
To investigate effects of ascending and descending direct current (ADC and DDC) on muscle strength evaluated with dynamometry. Muscle strength values in kilograms were compared in 3 groups (ADC, DDC, and control) before and after galvanic electrical intervention.

Methods:
A randomized clinical trial was performed in the Physiotherapy Laboratory of Andrés Bello University among 83 healthy volunteers. The intervention was a direct current session at an intensity of 4 mA for 12 minutes with 48-cm2 electrodes (dose: 48 mA · min; current density: 0.04 mA/cm2). The difference between the groups was galvanic therapy type applied. Current application followed a hand dynamometric test and myofeedback evaluation. The main outcome was maximum strength difference (MSdif) and its corresponding value in microvolts (μV-MSdif) obtained with myofeedback.

Results:
There were statistically significant changes regarding MSdif in groups who received direct current (p = 0.0001). These variations were also seen when comparing the 3 groups with the consideration of men (p = 0.0012) and women (p = 0.0021) separately. No statistically significant changes were observed in the μV-MSdif values (p = 0.9409).

Conclusions:
ADC can generate variations in grip strength after an intervention session, with an increase in strength of 8.9%. The increase in strength was observed both in men (6.7%) and in women (9%) of the ADC group.