Effects of acute trans-spinal neuromodulation on trunk posture and sacral motor output during gait in older adults.

Abstract

Age-related decline in trunk control during gait increases fall risk and limits mobility. Trans-Spinal direct current stimulation is a non-invasive technique that may modulate spinal motor output and improve neuromuscular function. This study investigated whether a single session of cathodal trans-spinal direct current stimulation alters trunk posture and sacral motor output in older adults during walking. Nineteen older and twenty young adults participated in a double-blind, sham-controlled study. Participants received either twenty minutes of cathodal trans-spinal direct current stimulation or sham stimulation while seated. Before and after stimulation, gait data were collected on a treadmill, including full-body kinematics, ground reaction forces, and surface electromyography from multiple lower-limb and trunk muscles. Electromyography data were projected onto a spinal topographical map to estimate segmental motor output, particularly at sacral levels. In older adults, trans-spinal direct current stimulation reduced the amplitude and shifted the timing of sacral motor output during walking, without significantly altering ground reaction forces. These neuromuscular changes were accompanied by a reduction in trunk flexion. No changes were observed in younger adults. A single session of cathodal trans-spinal direct current stimulation can acutely modulate sacral motor output and trunk posture in older adults without affecting kinetic parameters. These findings suggest that trans-spinal direct current stimulation may support clinical interventions aiming to address age-related neuromuscular decline during locomotion.