Blood pressure and plasma catecholamine responses to various challenges during exercise-recovery in man

Summary

The purpose of this study was to assess the effects of a 2 h cycle exercise (50%$\dot V_{O_2 \max }$) on heart rate (HR) and blood pressure (BP), and on plasma epinephrine (E) and norepinephrine (NE) concentrations, during the recovery period in seven normotensive subjects. Measurements were made at rest in supine (20 min) and standing (10 min) positions, during isometric exercise (hand-grip, 3 min, 25% maximal voluntary, contraction), in response to a mild psychosocial challenge (Stroop conflicting color word task) and during a 5-min period of light exercise (42±3%$\dot V_{O_2 \max }$). Data were compared to measurements taken on another occasion under similar experimental conditions, without a previous exercise bout (control). The results showed HR to be slightly elevated in all conditions following the exercise bout. However, diastolic and systolic BP during the recovery period following exercise were not significantly different from the values observed in the control situation. Plasma NE concentrations in supine position and in response to the various physiological and/or psychosocial challenges were similar in the control situation and during the recovery period following exercise. On the other hand plasma E (nmol · l⁻¹) was about 50% lower at rest (0.11±0.03 vs 0.23±0.04) as well as in response to hand-grip (0.21±0.04 vs 0.41±0.20) and the Stroop-test (0.21±0.05 vs 0.41±0.15) following the exercise bout. This reduction might reflect changes in plasma epinephrine removal accross the forearm due to changes in blood flow. However, it might also indicate a reduction in the activity of the adrenal medulla which might have some implications in the use of regular exercise in the control of BP in hyperadrenergic hypertensive subjects.