Differential Effects of Cycling Exercise on Pain Types in Patients with Early Parkinson's Disease: A Subgroup Analysis of a Randomized Pilot Trial.

Background: Pain in Parkinson's disease (PD) is common and arises from both central and peripheral mechanisms, manifesting as distinct subtypes. While physical exercise is considered one of the nonpharmacological treatments for managing pain in PD, it remains unknown how the effects of exercise differ depending on the type of pain. Objective: To explore the differential effects of cycling exercise on various pain subtypes in patients with early PD. Methods: In the randomized controlled pilot trial, 22 participants with early PD were initially assigned to the cycling exercise group and 11 to the control group. This exploratory subgroup analysis included 25 patients after applying the inclusion/exclusion criteria, comprising 16 cycling exercise participants and 9 controls. The exercise intervention consisted of 40-60 minutes of cycling, three sessions weekly, for 24 weeks. Pain subtypes were assessed using the King's PD Pain Scale. Changes in pain severity and newly developed pain were analyzed descriptively. Results: After 24 weeks, a greater proportion of participants in the cycling group showed improvement in fluctuation-related, nocturnal, and orofacial pain compared with controls. However, musculoskeletal pain newly developed in 40% of cycling participants, compared to 20% in the control group. For other pain subtypes, both groups showed similar patterns in pain severity changes and newly developed pain. Conclusion: Cycling exercise may alleviate fluctuation-related, nocturnal, and orofacial pain in PD but may also increase the risk of musculoskeletal pain in some cases. These observations warrant further large-scale investigations.