Cardiovascular, plasma norepinephrine, and thermal adjustments to prolonged exercise in young and older healthy humans

K. P. Davy, D. G. Johnson, D. R. Seals

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

Summary. We tested the hypothesis that the whole body energy expenditure, plasma norepinephrine, cardiovascular, and internal body temperature adjustments to prolonged submaximal exercise (i.e., ‘cardiovascular drift’) performed at the same per cent of peak oxygen uptake (per cent VO2peak) under thermoneutral ambient conditions would be smaller in older compared to young non‐physically trained men. Healthy young (25±1 years; VO2max = 49.3±1.6 ml kg‐1 min‐1; n=6) and older (66±2 years; VO2max = 31.5±2.3 ml kg‐1 min‐1; n=6) untrained men with similar levels of chronic physical activity were studied during pre‐exercise standing rest and serially during 45 min of constant load treadmill walking at ˜65%VO2peak (Ta=˜23±C; ˜40 RH). There were no group differences at rest. From rest to 5 min of exercise, the increases in heart rate were less (P<0–05), the changes in arterial blood pressure and per cent δ blood volume were not different, and the rise in plasma norepinephrine concentration was greater (P<0–05) in the older men vs. young controls. Consistent with our hypothesis, the increases in rectal temperature and plasma norepinephrine concentrations from 5 to 45 min of exercise were smaller in the older men (1.06–0.18 vs. 1.46±0.16±C and 110±132 vs. 443±189%, respectively, P<0.05). In contrast, the progressive increases in KO2, heart rate, and perceived effort, as well as the time‐dependent reductions in systolic, mean and diastolic arterial blood pressure and per cent δ blood volume, were not different in the two groups. Thus, the whole body energy expenditure and selected cardiovascular adjustments to prolonged submaximal treadmill exercise performed at the same per cent VO2peak under comfortable ambient conditions are not different in healthy, physical activity‐matched young and older men, despite a smaller elevation in internal body temperature in the latter.

Original languageEnglish (US)
Pages (from-to)169-181
Number of pages13
JournalClinical Physiology
Volume15
Issue number2
DOIs
StatePublished - Mar 1995

Keywords

  • ageing
  • blood pressure
  • cardiovascular drift
  • thermoregulation

ASJC Scopus subject areas

  • Physiology

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