Neuromuscular electrical stimulation can generate contractions through peripheral and central mechanisms. Direct activation of motor axons (peripheral mechanism) recruits motor units in an unnatural order, with fatigable muscle fibers often activated early in contractions. The activation of sensory axons can produce contractions through a central mechanism, providing excitatory synaptic input to spinal neurons which recruit motor units in the natural order. Presently, we quantified the effect of stimulation frequency (10-100Hz), duration (0.25-2 second high frequency bursts, or 20 seconds of constant frequency stimulation), and intensity (1-5%MVC torque generated by a brief 100Hz train) on the torque generated centrally. Electrical stimulation (1ms pulses) was delivered over the triceps surae in 8 subjects and plantarflexion torque was recorded. Stimulation frequency, duration, and intensity all influenced the magnitude of the central contribution to torque. Central torque did not develop at frequencies 20Hz, and was maximal at frequencies 80Hz. Increasing the duration of high frequency stimulation increased the central contribution to torque, as central torque developed over 11 seconds. Central torque was greatest at a relatively low contraction intensity. The largest amount of central torque was produced by a 20 second, 100Hz train (10.7±5.5%MVC) and by repeated 2 second bursts of 80 or 100Hz stimulation (9.2±4.8%MVC and 10.2±8.1%MVC, respectively). Therefore, central torque was maximized by applying high frequency, long duration stimulation while avoiding antidromic block by stimulating at a relatively low intensity. If, as hypothesized, the central mechanism primarily activates fatigue resistant muscle fibers, generating muscle contractions through this pathway may improve rehabilitation applications.