Background: Impaired gait and postural stability are cardinal motor symptoms in Parkinson’s disease (PD). Treadmill training improves gait characteristics in PD.

Objective: This study investigates if postural perturbations during treadmill training improve motor performance and particularly gait and postural stability in PD.

Methods: This work presents secondary outcome measures of a pilot randomized controlled trial. PD patients (n= 43) recruited at the University Hospital Erlangen were randomly allocated to the experimental (perturbation treadmill training, PTT, n= 21) or control group (conventional treadmill training, CTT, n= 22). Outcome measures were collected at baseline, after 8 weeks of intervention, and 3 months follow-up. Motor impairment was assessed by the Unified Parkinson Disease Rating Scale part-III (UPDRS-III), Postural Instability and Gait Difficulty score (PIGD), and subitems ‘Gait’and ‘Postural stability’by an observer blinded to the randomization. Intervention effects were additionally compared to progression rates of a matched PD cohort (n= 20) receiving best medical treatment (BMT). Results: Treadmill training significantly improved UPDRS-III motor symptoms in both groups with larger effect sizes for PTT (–38%) compared to CTT (–20%). In the PTT group solely, PIGD–34%, and items ‘Gait’–50%, and ‘Postural stability’–40% improved significantly in comparison to CTT (PIGD-24%,‘Gait’–22%,‘Postural stability’–33%). Positive effects persisted in PTT after 3 months and appeared to be beneficial compared to BMT. Conclusions: Eight weeks of PTT showed superior improvements of motor symptoms, particularly gait and postural stability. Sustainable effects indicate that PTT may be an additive therapy option for gait and balance deficits in PD.