Individuals with spinal cord injury (SCI) are at high risk of developing pressure sores, in part due to high sitting pressures under the buttocks. PURPOSE: To evaluate the effect of ES-induced activation of the gluteal and hamstring muscles on the sitting pressure in individuals with SCI. METHODS: Five men with SCI received ES in their own daily-use wheelchair while sitting pressure under the buttocks was measured. The subjects wore a Bioshort (Bioflex Inc.) with built-in electrodes. Two 3-hr protocols were randomly applied, both consisting of 3 min of stimulation (all muscles simultaneously activated) followed by 17 min rest. Prot. A had a 1s:1s and prot. B a 1s:4s on-off duty cycle. Peak pressure under the buttocks and pressure gradient were calculated. RESULTS: For both protocols, peak pressure decreased (p<0.05) from 183±13 (A) and 179±14 (B) during rest to 168±17 (A) and 147±24 (B) mmHg during the 3-hr stimulation periods. The pressure gradient tended (p<0.1) to decrease for both protocols indicating an improved pressure distribution. Prot. B showed in general superior effects. CONCLUSIONS: ES-induced activation of the gluteal and hamstring muscles in sitting individuals with SCI causes a temporary decrease in peak sitting pressure under the buttocks and an improved pressure distribution.