Interface pressure reduction in the sacral and ischial regions during neuromuscular electrical stimulation at 60° head-of-bed elevation

Abstract

This study investigated whether neuromuscular electrical stimulation (NMES) applied to the gluteus maximus alone or in combination with the hamstrings redistributes interface pressure in the sacral and ischial regions during 60° head-of-bed elevation. Twenty healthy adults (10 males, 10 females; mean age 20.7 ± 0.5 years; BMI ≤ 20 kg/m²) participated. NMES was delivered using adhesive surface electrodes while participants were positioned at 60° head elevation and 20° leg elevation. Interface pressure was measured under three randomized conditions: control (no NMES), NMES applied to the gluteus maximus only, and NMES applied to both the gluteus maximus and hamstrings. Each condition lasted 3 min. Peak pressure index (PPI) was calculated separately for the sacral and ischial regions using region-specific averaging windows to reflect differences in pressure distribution. Data were analyzed using one-way repeated-measures ANOVA with Bonferroni-adjusted post hoc comparisons. Sacral PPI was significantly lower in both NMES conditions than in the control condition (both p < 0.001), with no significant difference between the two NMES conditions. Ischial PPI was significantly lower when NMES was applied to both the gluteus maximus and hamstrings than in the control and gluteus maximus-only conditions (both p < 0.001), whereas no significant difference was observed between the control and gluteus maximus-only conditions. These findings suggest NMES may reduce sacral and ischial interface pressure during high head-of-bed elevation, with additional hamstring stimulation associated with greater ischial pressure reduction. Further studies are needed in at-risk populations.