ABSTRACT
Impedance cardiography (IC) is a non-invasive method for assessing cardiovascular hemodynamics, and has been utilised during exercise, exclusively on a cycle ergometer. Mode-specific differences in cardiovascular hemodynamics during exercise have previously been identified, but the ability of IC to identify these differences has not been explored. Therefore, we examined the repeatability of cardiovascular hemodynamics within and between exercise modes on the treadmill (TM) and cycle (CY) ergometer. Twenty-one men (age = 21.4 ± 0.5 yr) performed four maximal exercise, two TM and two CY. Within each test, two, five-minute stages were completed corresponding to moderate and vigorous exercise intensities, respectively. Oxygen consumption (VO2) was measured continuously during each test. Hemodynamic measures were obtained via IC, and included cardiac output (CO), heart rate (HR), stroke volume (SV), end diastolic volume (EDV), ejection fraction (EF), and systemic vascular resistance (SVR). Repeated measures ANOVA revealed that within TM exercise, there was a main effect for trial with HR only. There were no main effects for trial within CY exercise. Across exercise modes, there were significant main effects for mode with HR, EDV, and SVR. CY exercise resulted in a higher HR, lower SV and EDV, consistent with previous findings, utilising more criterion and invasive methods. Results suggest that hemodynamics, as assessed by IC, are repeatable within TM and CY exercise. In addition, it appears as though IC is capable of detecting mode-specific differences in hemodynamics, suggesting IC to be a useful assessment tool during exercise.
