RZ Interval as an Impedance Cardiography Indicator of Effort-Related Cardiac Sympathetic Activity.

Research on effort and motivation commonly assesses how the sympathetic branch of the autonomic nervous system affects the cardiovascular system. The cardiac pre-ejection period (PEP), assessed via impedance cardiography, is a common outcome, but assessing PEP requires identifying subtle points on cardiac waveforms. The present research examined the psychometric value of the RZ interval (RZ), which has recently been proposed as an indicator of sympathetic activity, for effort research.

Do depressive symptoms "blunt" effort? An analysis of cardiac engagement and withdrawal for an increasingly difficult task.

Research on depression and effort has suggested "depressive blunting"-lower cardiovascular reactivity in response to challenges and stressors. Many studies, however, find null effects or higher reactivity. The present research draws upon motivational intensity theory, a broad model of effort that predicts cases in which depressive symptoms should increase or decrease effort.