Determination of Cardiac Function Using Impedance Cardiography During Jogging With and Without Breast Support

The goal of this study was to use a non-invasive method of impedance cardiography to investigate the consistency of cardiac variables, in parallel with metabolic function. Thirteen healthy females underwent two randomized jogging conditions: without breast support (NB) and with breast support (jogging bra, JB). Cardiorespiratory and metabolic functions were continuously recorded at rest, during exercise on the treadmill at a constant speed of 4 mph at 60, 70 and 80% of age-predicted maximum heart rate followed by a 5-min recovery. The results showed that there were no significant differences in resting cardiac variables, including cardiac output (CO), heart rate (HR), stroke volume (SV), end diastolic volume (EDV), end systolic volume (ESV) and cardiac index (CI). The parallel intensity-dependent characteristics of both cardiorespiratory and metabolic variables during jogging were also determined. The results showed normal cardiac functions during and after jogging with no significant differences of CO, HR, SV, EDV, ESV and CI between two conditions (P > 0.05). Metabolic variables showed no significant differences between the two conditions (P > 0.05) for oxygen consumption (\( {\dot{\rm{V}}\rm{O}}_{\text{2}} \)), carbon dioxide production (\( {\dot{\rm{V}}\rm{CO}}_{2} \)) and respiratory exchange ratio (RER). With narrow ranges of the standard errors of the mean and parallel alterations of metabolism at rest, during exercise and recovery from two conditions, this study concluded that a non-invasive impedance cardiography method can possibly reflect changes of both cardiorespiratory and metabolic functions. In addition, it is suggested that breast supports in females during treadmill running induce no limitations on both cardiorespiratory and metabolic functions.