Home-Based time-constrained reactive training enhances movement speed in upper and lower limbs in Parkinson's disease: A randomized controlled trial

Bradykinesia and delayed step initiation are central features of Parkinson's disease (PD) and have been linked to reduced movement vigor. Evidence suggests that externally imposed urgency may upregulate vigor and improve motor speed. Previous home-based cueing interventions without time limits improved gait but failed to reduce reaction times, indicating that time constraints may be critical. We conducted a randomized controlled trial to evaluate whether time-constrained, visually guided reaching and stepping exercises enhance response speed in PD. Sixty participants with idiopathic PD (Hoehn & Yahr I-III) completed 24 supervised, home-based sessions using a set of small interactive devices that provided visual and auditory cues and recorded response times. The experimental group trained with time windows adapted during each session to maintain ∼80% success, receiving immediate success/failure feedback, while the control group performed identical tasks without time restrictions. Response times were assessed before and after training with choice stepping and reaching reaction time tasks in a laboratory setting, alongside gait and mobility tests. Repeated measures ANOVA revealed significant group × time interactions favoring the experimental group for both reaching (p < 0.05) and stepping (p < 0.001) reaction times, with medium-to-large effect sizes, whereas controls showed no change. Gait speed improved in both groups, with no additional between-group differences. These findings demonstrate that introducing temporal urgency during reactive training produces meaningful improvements in bradykinesia-related response times in individuals with PD, supporting the integration of time-constrained cueing into scalable home-based rehabilitation. ClinicalTrials.gov: NCT05829915.