Cardiovascular response to passive cycle exercise

Cardiovascular response of trained males (N = 20) and fit but untrained controls (N = 10) were examined during rest and passive cycle exercise (PCE). Heart rate (HR), stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR), and mean arterial pressure (MAP) were measured during PCE for 6 min at intensities of 30 and 60 rpm. Also vagal influence on the heart was assessed through time series analysis of heart period variability (HPVts) at high and medium frequencies. Electromyography (EMG) was used to monitor muscle activity during PCE. During PCE no differences in cardiovascular response were found between the trained and untrained groups; thus groups were combined for the remainder of the analysis. Results indicated that during light and medium PCE all subjects combined showed a significant increase in HR, CO, and MAP and a significant decrease in HPVts (P < 0.001). The increase in HR during passive exercise may be a result of the stimulation of mechanoreceptors. The small and similar SV response during PCE of both groups suggests that the muscle pumps may not be effective during this form of passive exercise.