Effects of ramp time on sensory, motor and tolerance thresholds during exogenous electrical stimulation.

This investigation examined the effects of ramp time on the current intensity needed to elicit sensory, motor and pain tolerance response. Forty-seven healthy subjects were randomly divided into three groups. Subjects in group one (no. 17), group two (no. 15), and group three (no. 15) had the onset (ramp time) knob present at 1.0, 3.5 and 5.0 seconds, respectively. Subsequently, the wrist and finger flexors of the dominant hand were stimulated following standardized instructions. For each subject, the current intensity needed to elicit: (1) the sensory response, (2) minimum perceptible contraction, and (3) the maximum tolerance level of painful stimulation was determined. Significant F ratio was found for the current intensity at different perceptual level (p less than 0.5) but not for ramp time (p greater than .05). The findings suggest that with the stimulator used in this study, ramp time has no effect on the three basic excitatory responses, i.e., thresholds of sensory, motor and painful stimulation.