Effects of Medium-frequency Electrical Stimulation Combined with Near-Infrared Light on Quadriceps Function and Independent Walking in Patients with Spinal Cord Injury

OBJECTIVE: To compare quadriceps electromyographic activity and deep femoral artery hemodynamics between individuals with spinal cord injury (SCI) and healthy controls and to preliminarily explore the effects of combined medium-frequency electrical stimulation (MFES) and near-infrared (NIR) therapy. DESIGN: A two-phase study comparing 36 SCI individuals with 15 healthy controls (Phase I), then tested a three-week nonrandomized, controlled, pre-post-intervention in 18 individuals with SCI (Phase II). Participants received MFES plus NIR with conventional rehabilitation or conventional rehabilitation alone (n=9/group). Outcomes included quadriceps electromyographic activity, deep femoral artery hemodynamics, muscle strength, spasticity, functional independence, and walking ability. RESULTS: Compared with healthy controls, individuals with SCI had less quadriceps electromyographic activation and impaired deep femoral artery blood-flow-related parameters. In Phase II, the treatment group present within-group improvements across all assessed outcomes, whereas only right peak systolic velocity and walking ability significantly differed between the groups. CONCLUSION: In this study, impaired quadriceps activation and altered deep femoral artery hemodynamics were evident in patients with SCI. Combined MFES and NIR therapy may improve muscle activation, femoral artery blood-flow velocity, and walking ability; however, these findings are preliminary and require confirmation in larger, randomized studies involving additional lower-limb muscles and vascular territories.