Improved cognitive flexibility after high-intensity interval training (HIIT) in individuals with Parkinson's disease: a pilot randomized controlled trial.

Abstract

Background: People with Parkinson's disease (PwPD) commonly experience impairments in both motor and cognitive domains, particularly executive function and cognitive flexibility. While aerobic exercise may benefit non-motor domains, it remains unclear whether high-intensity interval (HIIT) provides superior cognitive benefits compared to intensive continuous endurance training (CT). This randomized pilot study investigated whether HIIT on a stationary bike leads to greater improvements in cognitive performance in PwPD than high-intensity endurance training on a stationary bike, with the aim of providing preliminary evidence of efficacy for a larger-scale RCT.

Methods: Twenty people with Parkinson's disease were randomly assigned to either an HIIT group or a control group that performed CT. Both interventions were performed on a stationary cycle ergometer three times per week for three weeks (30 min/session), matched for overall training duration. HIIT consisted of alternating 30-second intervals at 75% and 90% of maximum heart rate, while the control group trained continuously at 85% of maximum heart rate. Primary outcomes included executive function such as cognitive flexibility and inhibitory control assessed by the Trial Making Test (TMT) and Stroop tests. Secondary outcomes comprised aerobic capacity (VO₂ max), balance (Mini-BESTest), motor parkinsonian symptoms (Unified Parkinson Disease Rating Scales II-III), freezing of gait, and quality of life (Parkinson Disease Questionnaire-39). Pre-and post-intervention assessments were compared using 2 × 2 ANOVA and paired t-tests.

Results: All participants completed the intervention. The HIIT group demonstrated significant within-group improvements in TMT-B (p = 0.010) and Stroop III (p = 0.019) indicating enhanced cognitive flexibility and inhibitory control, whereas no significant changes were observed in the control group. The TMT-B test revealed a significant interaction effect between the groups (p = 0.003, F = 12.716, and pη ² = 0.459). Both groups showed significant improvements in balance and motor function (both p < 0.001). VO2max increased significantly only in the CT group (p = 0.010). No differences were found for quality of life or freezing of gait (p = 0.530).

Discussion and conclusions: HIIT on a cycle ergometer is feasible and well tolerated in PwPD and may preferentially enhance executive function such as cognitive flexibility and inhibitory control compared with CT over a short intervention period. Although exploratory, these findings suggest HIIT could be a promising strategy targeting cognitive deficits in PwPD. However, larger well-powered trails with longer follow-up are warranted to confirm these preliminary results and clarify underlying mechanisms.