Search for: All records

The rate of adjustment in a movement, driven by feedback error, is referred to as the adaptation rate, and the rate of recovery of a newly adapted movement to its unperturbed condition is called the de-adaptation rate. The rates of adaptation and de-adaptation are dependent on the training mechanism and intrinsic factors such as the participant's sensorimotor abilities. This study investigated the facilitation of the motor adaptation and de-adaptation processes for spatiotemporal features of an asymmetric gait pattern by sequentially applying split-belt treadmill (SBT) and asymmetric rhythmic auditory cueing (ARAC). Methods: Two sessions tested the individual gait characteristics of SBT and ARAC, and the remaining four sessions consisted of applying the two interventions sequentially during training. The adjustment process to the second intervention is referred to as “re-adaptation” and is driven by feedback error associated with the second intervention. Results: Ten healthy individuals participated in the randomized six-session trial. Spatiotemporal asymmetries during the adaptation and post-adaptation (when intervention is removed) stages were fitted into a two-component exponential model that reflects the explicit and implicit adaptation processes. A double component was shown to fit better than a single-component model. The decay constants of the model were indicative of the corresponding timescales and compared between trials. Results revealed that the explicit (fast) component of adaptation to ARAC was reduced for step length and step time when applied after SBT. Contrarily, the explicit component of adaptation to SBT was increased when it was applied after ARAC for step length. Additionally, the implicit (slow) component of adaptation to SBT was inhibited when applied incongruently after ARAC for step time. These outcomes show that the role of working motor memory as a translational tool between different gait interventions is dependent on (i) the adaptation mechanisms associated with the interventions, (ii) the targeted motor outcome of the interventions; the effects of factors (i) and (ii) are specific to the explicit and implicit components of the adaptation processes; these effects are unique to spatial and temporal gait characteristics. 

This study categorizes the response to asymmetric rhythmic cues into distinct levels of adaptation using changes in their step velocity. Motion capture and force data were collected from healthy individuals undergoing split-belt treadmill and rhythmic cueing interventions. This allowed comparative insights into two distinct adaptation mechanisms (sensorimotor and instructional adaptation) corresponding to the interventions and integration of those findings with trade-off mechanisms within spatiotemporal and kinetic gait parameters. Interlimb gait harmony (corresponding to differences between left and right step velocities) was significantly different between the gait interventions, indicating underlying differences in the dominant adaptation mechanisms driving them. The trade-off mechanisms among step length, swing time, and push-off forces were significantly different (i) between the gait interventions and (ii) between adaptable and non-adaptable subject groups to external rhythmic cues. This suggests that an orthogonal linear relationship between propulsion and either spatial or temporal features may indicate the adaptation mechanism that has a greater contribution towards their motor outcome. 

This study explores the influence of Auditory Rhythmic Asymmetric Cueing (A-RAC), Tactile Rhythmic Asymmetric Cueing (T-RAC), and their combination (AT) on key kinetic gait parameters in gait rehabilitation: Vertical Ground Reaction Force Asymmetry (GRF), Push-off Force Asymmetry (POF), and Braking Force Asymmetry (BRK). Utilizing the Computer-Assisted Rehabilitation Environment (CAREN) with 18 participants, this research examines these interventions' effectiveness in generating asymmetric gait. While the results during adaptation indicate that BRK was significantly affected by both A-RAC (p = 0.001) and AT (p = 0.003), only A-RAC had a significant effect on GRF (p = 0.002) during adaptation. None of the interventions significantly altered POF, suggesting its resistance to sensory cue modification. These findings provide valuable insights for enhancing gait rehabilitation strategies, particularly in addressing vertical load