TY - JOUR
T1 - Sympathoadrenal-circulatory regulation during sustained isometric exercise in young and older men
AU - Taylor, J. A.
AU - Hand, G. A.
AU - Johnson, D. G.
AU - Seals, D. R.
PY - 1991
Y1 - 1991
N2 - The aim of this study was to test the hypothesis that the arterial blood pressure, vasoconstrictor, and sympathoadrenal adjustments to sustained submaximal isometric exercise become augmented with advancing age in humans. Fourteen young (26 ± 1 yr) and 14 older (66 ± 1 yr) healthy males performed isometric handgrip exercise at 30% of maximal voluntary force until exhaustion (inability to maintain target force). Maximal handgrip force was quite similar in the young and older subjects (402 ± 20 vs. 392 ± 20 N, respectively). The two groups did not differ significantly on any variable at rest. During sustained handgrip to exhaustion, peak levels of both perceived exertion and contracting forearm electromyographic activity were similar in the young and older men, suggesting equivalent voluntary efforts. Exercise time was not different in the two groups (315 ± 27 s in young vs. 339 ± 17 s in older men). Throughout exercise the increases in arterial blood pressure were very similar in the young and older subjects. Heart rate increased less (P < 0.05), but stroke volume (impedance cardiography) tended to decrease less (not significant) in the older men; thus the increases in cardiac output were not different in the two groups. During the latter portion of exercise, systemic vascular resistance tended to increase in both the young and older men, with no significant group differences. The blood flow responses in the whole calf (venous occlusion plethysmography) and the calf skin (laser-Doppler velocimetry) were similar in the young and older subjects, as were the corresponding increases in vascular resistance. Antecubital venous plasma norepinephrine and epinephrine responses also were not different in the two groups. We conclude that during sustained submaximal isometric muscle contractions, the regulation of arterial blood pressure, nonactive limb and systemic hemodynamics, and sympathoadrenal activation is not modulated by human aging.
AB - The aim of this study was to test the hypothesis that the arterial blood pressure, vasoconstrictor, and sympathoadrenal adjustments to sustained submaximal isometric exercise become augmented with advancing age in humans. Fourteen young (26 ± 1 yr) and 14 older (66 ± 1 yr) healthy males performed isometric handgrip exercise at 30% of maximal voluntary force until exhaustion (inability to maintain target force). Maximal handgrip force was quite similar in the young and older subjects (402 ± 20 vs. 392 ± 20 N, respectively). The two groups did not differ significantly on any variable at rest. During sustained handgrip to exhaustion, peak levels of both perceived exertion and contracting forearm electromyographic activity were similar in the young and older men, suggesting equivalent voluntary efforts. Exercise time was not different in the two groups (315 ± 27 s in young vs. 339 ± 17 s in older men). Throughout exercise the increases in arterial blood pressure were very similar in the young and older subjects. Heart rate increased less (P < 0.05), but stroke volume (impedance cardiography) tended to decrease less (not significant) in the older men; thus the increases in cardiac output were not different in the two groups. During the latter portion of exercise, systemic vascular resistance tended to increase in both the young and older men, with no significant group differences. The blood flow responses in the whole calf (venous occlusion plethysmography) and the calf skin (laser-Doppler velocimetry) were similar in the young and older subjects, as were the corresponding increases in vascular resistance. Antecubital venous plasma norepinephrine and epinephrine responses also were not different in the two groups. We conclude that during sustained submaximal isometric muscle contractions, the regulation of arterial blood pressure, nonactive limb and systemic hemodynamics, and sympathoadrenal activation is not modulated by human aging.
KW - Aging
KW - Autonomic nervous system
KW - Maximal force
KW - Muscle endurance
KW - Plasma catecholamines
UR - http://www.scopus.com/inward/record.url?scp=0026332912&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026332912&partnerID=8YFLogxK
U2 - 10.1152/ajpregu.1991.261.5.r1061
DO - 10.1152/ajpregu.1991.261.5.r1061
M3 - Article
C2 - 1951754
AN - SCOPUS:0026332912
SN - 0002-9513
VL - 261
SP - R1061-R1069
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 5 30-5
ER -