Chronotropic Incompetence Does Not Impede Attainment of High-Intensity Exercise During Non-Contact Boxing in Parkinson’s Disease

Recent evidence points to the effect of chronotropic incompetence (CI), which refers to a blunted heart rate (HR) response to exercise, influencing physiological outcomes in people with Parkinson’s disease (PD). This study explores the effect of CI on physiological responses and examines whether a high-intensity training zone is attained during non-contact boxing training in people with PD. In total, 11 PD participants with CI (PDCI), 13 without CI (PD non-CI), and 14 age-matched controls performed two non-contact boxing sessions on different days. The primary outcomes were the maximum HR (HRmax), average HR (HRavg), percentage of the highest HR from cardiopulmonary exercise test (%HR-CPET) and predicted maximum HR (%MA-PHR), time exercising above 85%HRmax (HI-85%), and second ventilatory threshold (HI-VT2). PDCI participants displayed significantly lower HRavg and HRmax values during all rounds than PD non-CI participants and controls for both sessions (<i>p</i> ≤ 0.001). No significant differences were observed between PD non-CI participants and controls (<i>p</i> ≥ 0.05). Although all participants exercised at approximately 100% of %HR-CPET, PDCI participants showed a significantly lower %MA-PHR than PD non-CI participants and controls (<i>p</i> ≤ 0.001). HI-85% and HI-VT2 were not significantly different between PDCI and PD non-CI participants. Despite exhibiting a lower absolute HRmax and HRavg during boxing compared to PD non-CI participants and aged-match controls, PDCI participants exercise at a similar intensity within the high-intensity training zone when expressed as a percentage of the individualized HRmax.