Tactile Biofeedback That Targets Stance Time Acutely Modulates Propulsion Mechanics in Healthy Gait

Biofeedback is effective in modifying and improving targeted gait parameters in both healthy individuals and those with chronic stroke. However, prior studies have largely focused on the variable targeted by biofeedback and rarely report changes in other gait features. Given the interdependent nature of gait, alterations in one parameter may induce changes in other features. Thus, we aimed to determine whether tactile biofeedback to the plantar surfaces instructing stance time increases would increase propulsive gait features, such as trailing limb angles (TLA), peak propulsive forces, and propulsive impulses. 8 healthy individuals walked with tactile stimulation instructing varying levels of stance time increase targets (small, medium, and large) to one limb at a time. These stance time targets were calculated using symmetry ratios ranging from 0.775–1.225. This feedback instructed subjects to delay their push off, and thus their toe off, after a heel strike. During the large stance time increase feedback target, subjects increased their stance time (0.23 ± 0.02 seconds, p < 0.001), and consequently their TLA (8.1 ± 0.8°, p = 0.001), peak propulsion (8.1 ± 1.1%BW, p = 0.002), and their propulsive impulse (2.9 ± 0.3%BW·s, p = 0.002) compared to no feedback. Stance time changes were significantly correlated to TLA (R ²  = 0.80, p < 0.001), and propulsive impulse (R ²  = 0.81, p < 0.001), but to a lesser degree for peak propulsive force (R ²  = 0.72, p < 0.001) when accounting for subject variances. These results provide evidence for a biofeedback tool that influences propulsive features that only instructs stance times. This may demonstrate the future application of a cheaper alternative for stroke survivors to improve the propulsion of the paretic limb compared to external assistances such as exoskeletons or ground reaction force biofeedback. Such a device could be an effective tool in post-stroke gait rehabilitation, for targeting improvements in the temporal and propulsive function of the paretic limb at the same time.