Autonomic and vascular responses to reduced limb perfusion.

The purpose of this study was to examine hemodynamic responses to graded muscle reflex engagement in human subjects. We studied seven healthy human volunteers [24 +/- 2 (SE) yr old; 4 men, 3 women] performing rhythmic handgrip exercise [40% maximal voluntary contraction (MVC)] during ambient and positive pressure exercise (+10 to +50 mmHg in 10-mmHg increments every minute). Muscle sympathetic nerve activity (MSNA), mean arterial blood pressure (MAP), and mean blood velocity were recorded.

Aging and the exercise pressor reflex in humans.

Background: Blood flow limitation to exercising muscles engages the muscle reflex during exercise, evoking an increase in heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA).

Methods And Results: In the current study, we examined forearm flow and autonomic responses to ischemic handgrip in young and older subjects. We studied 6 younger subjects (mean age 23.

Venous plasma potassium is not associated with maintenance of the exercise pressor reflex in humans.

Increases in the concentration of interstitial potassium concentration during exercise may play a role in the modulation of the cardiovascular response to exercise. However, it is not known if changes in potassium correlate with indexes of muscle reflex engagement. Eight healthy subjects performed dynamic [rhythmic handgrip (RHG)] and static handgrip (SHG) exercise at 40% of maximal voluntary contraction.