Aftereffects of exercise on regional and systemic hemodynamics in hypertension.

Abstract

Several studies have indicated that a single bout of physical exercise induced a significant antihypertensive effect during the hours after the activity. However, little information is presently available on the underlying hemodynamic changes. We examined 13 essential hypertensive patients and nine nonnotensive subjects in a randomized, crossover study design during 3 hours after a 30-minute period of upright leg cycling at 50% of peak aerobic capacity and during 3 hours after a 30-minute control period of rest Blood pressure, heart rate, cardiac output, total peripheral resistance, and regional vascular resistance in the forearm as well as venous plasma catecholamine concentrations were measured repeatedly. After exercise, systolic (-11±2 mm Hg) and diastolic (-4±1 mm Hg) blood pressures, total peripheral resistance (-27±5%), forearm vascular resistance (-25±6%), and plasma norepinephrine levels (-21±7%) were significantly (p<0.05) decreased, and cardiac output was increased (+31 ±8%) compared with control in hypertensive subjects. In contrast, in normotensive subjects blood pressure, forearm vascular resistance, and plasma norepinephrine were unchanged, and systemic hemodynamics changed to a lesser extent than in hypertensive subjects after exercise. It is concluded that a decrease in regional vascular resistance in skeletal muscles and possibly in the skin in hypertensive patients may contribute importantly to the antihypertensive effect of prior exercise. A decreased sympathetic nervous activity, as seen from lower plasma norepinephrine levels, may be involved in this effect (Hypertension 1992;19:183-191)

Potential causes, mechanisms, and implications of post exercise hypotension

“…In humans, it is common to observe an increased heart rate during some or all of the hypotensive period, 20,22,33,35,58,63,77 whereas rodents often display decreased or unchanged heart rates. 30,[48][49][50]54 Of interest is that, with the exception of one study, 43 changes in human cardiac output post exercise appear dependent on the initial state of hypertension. Those studies reporting indices of Q · c in normotensives found increases in Q · c during the post exercise hypotensive period, whereas hypertensives showed a decreased Q · c. 13 …”

“…A number of studies have found decreased peripheral resistance at sites other than those of the exercising muscle, suggesting that the reduction is a whole body phenomenon. 22,35,43 However, Hagberg et al 13 found increases in total peripheral resistance in older…”

“…10,11,19,22,24,[31][32][33]35,41,[43][44][45][59][60][61]63,71,72 Treadmill exercise at similar intensities has also been documented to elicit PEH. 14,15,20,25,34,40,[55][56][57][58] Direct comparisons of the effect of exercise intensity have, for the most part, found that PEH occurs independent of exercise intensity.…”

“…9,10,15,16,19,24,32,[34][35][36][37][38][39][41][42][43]45,47,[57][58][59][60]63,[75][76][77] Inter-experimental comparisons are difficult across studies, since a variety of exer-Journal of Human Hypertension cise intensities and blood pressure measurement techniques have been used.…”

“…Hypotension has been found to persist for greater than the one hour after moderate to intense exercise in which this increased plasma volume can occur. 20,43 Thus, it would appear unlikely that reductions in plasma volume are responsible for PEH.…”