The effect of chronotropic incompetence on physiologic responses during progressive exercise in people with Parkinson's disease

Abstract

Purpose: Heart rate (HR) response is likely to vary in people with Parkinson's disease (PD), particularly for those with chronotropic incompetence (CI). This study explores the impact of CI on HR and metabolic responses during cardiopulmonary exercise test (CPET) in people with PD, and its implications for exercise intensity prescription.

Methods: Twenty-eight participants with mild PD and seventeen healthy controls underwent CPET to identify the presence or absence of CI. HR and metabolic responses were measured at submaximal (first (VT1) and second (VT2) ventilatory thresholds), and at peak exercise. Main outcome measures were HR, oxygen consumption (VO₂), and changes in HR responses (HR/WR slope) to an increase in exercise demand.

Results: CI was present in 13 (46%) PD participants (PDCI), who during CPET, exhibited blunted HR responses compared to controls and PD non-CI beyond 60% of maximal workload (p ≤ 0.05). PDCI presented a significantly lower HR at VT2, and peak exercise compared to PD non-CI and controls (p ≤ 0.001). VO₂ was significantly lower in PDCI than PD non-CI and controls at VT2 (p = 0.003 and p = 0.036, respectively) and at peak exercise (p = 0.001 and p = 0.023, respectively).

Conclusion: Although poorly understood, the presence of CI in PD and its effect on HR and metabolic responses during incremental exercise is significant and important to consider when programming aerobic exercises.

Keywords: Cardiopulmonary exercise test; Exercise prescription; Heart rate; Oxygen consumption.

Fig. 1

Represents heart rate (HR) responses at rest, submaximal (first (VT1) and second (VT2) ventilatory thresholds) and maximal exercise intensities. PD participants with blunted HR response (PDCI) exhibited significantly lower HR at VT2 and during peak exercise, compared to PD participants without chronotropic incompetence (PD non-CI) and controls (p ≤ 0.001). Differences in heart rate at VT2 (p = 0.738) and peak exercise (p = 0.332) are not significant between PD non-CI group and controls

Fig. 2

Represents changes in heart rate (HR) in beats per minute (bpm) from 30 to 100% of the maximum workload (WRmax) during the cardiopulmonary exercise test (CPET). As the workload increased, the reduced increase in heart rate responses became more apparent in PD with chronotropic incompetence (PDCI) compared to those without chronotropic incompetence (PD non-CI) and controls

Fig. 3

Represents the difference in oxygen consumption (VO₂) at submaximal (first (VT1) and second (VT2) ventilatory thresholds) and maximal exercise intensities between groups. PD participants with blunted HR response (PDCI) presented significantly lower VO₂ compared to both PD participants without chronotropic incompetence (PD non-CI) and the control group at VT2 (p = 0.003 and p = 0.036) and peak exercise (p = 0.001 and p = 0.023)