Evaluating Catchlike-Inducing Pulse Train in Angle Production During Simulated Slow-Speed Walking for Foot Drop Correction by Functional Electrical Stimulation
Lina YAMADA, Takashi WATANABE
Vol. 14 (2025) p. 340-346
This study aimed to compare the effectiveness of catchlike-inducing pulse train (CIT) and constant frequency pulse train (CFT) in producing ankle dorsiflexion angle during simulated slow-speed walking. Sixteen healthy subjects were divided into two groups: a 20-Hz stimulation group (CFT: 20-Hz pulses, CIT: 100-Hz doublet followed by 20-Hz pulse train) (N = 8) and a 30-Hz stimulation group (CFT: 30-Hz pulses, CIT: 200-Hz doublet followed by 30-Hz pulse train) (N = 8). Electrical stimulation (1 second on, 1.5 seconds off) was applied for 15 minutes while subjects were seated, simulating slow-speed walking. Ankle angles were measured continuously throughout the 15-minute stimulation, and fatigue assessments (force, twitch force, doublet force, M-wave, and subjective fatigue rating) were performed before and after the stimulation. In the 20-Hz stimulation group, the ankle angles generated by CIT were significantly larger than those generated by CFT 12 to 15 minutes after stimulation began (p < 0.05). In the 30-Hz stimulation group, the ankle angles generated by CIT were significantly larger than those by CFT 8 to 12 minutes and 14 to 15 minutes after stimulation began (p < 0.05). Remarkably, the angle generated by CFT decreased by more than 2.5° within the first 10 minutes of stimulation in both groups. Fatigue assessments showed a significant decrease in force following CFT (p < 0.05 in the 20-Hz group and p < 0.01 in the 30-Hz group), whereas CIT did not result in a significant change in force production. The finding that CIT allowed longer maintenance of the target angle compared to CFT suggests its potential to improve the effectiveness and safety of functional electrical stimulation (FES) that applies intermittent, repetitive electrical stimulation for longer periods of time. Investigating the application of CIT in FES control may offer a straightforward and effective method for achieving and maintaining the desired angle in FES applications, such as FES-based foot drop correction.