Mechanisms for the responses of cardiac muscle to physical activity in old age

Charlotte A. Tate, Michael F. Hyek, George Taffet

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

The decline of maximal cardiac output (Q̇max) is a major factor responsible for the lower maximal oxygen consumption of elderly mammals. The lower Q̇max is associated with aging-related decreases in maximal heart rate (HRmax) and maximal stroke volume (SVmax). The mechanism(s) for the slower HRmax, unchanged by exercise training, is unknown. The decrement in SVmax, however, can be improved, as shown by the enhanced systolic and diastolic properties of the elderly heart after exercise training. One major problem is diastolic dysfunction observed in the absence of disease. Diastolic dysfunction (a decrease in peak ventricular filling after systole or a prolonged relaxation of contracted muscle) results from in part a downregulation of the sarcoplasmic reticulum's (SR) calcium ATPase that sequesters cytosolic calcium via the hydrolysis of ATP. Exercise training of sedentary old mammals produces a faster relaxation and an upregulation of the SR calcium ATPase. Yet the characteristic shift of myosin toward the slower isoform is unaltered by exercise training. The molecular signals and mechanisms underlying these aging-related alterations in sedentary and physically active individuals are unknown. An enhancement of cardiac function by exercise training, though, is preserved in advanced age.

Original languageEnglish (US)
Pages (from-to)561-567
Number of pages7
JournalMedicine and science in sports and exercise
Volume26
Issue number5
DOIs
StatePublished - May 1994

Keywords

  • Cardiac output
  • Contractile properties
  • Gene expression
  • Myosin
  • Sarcoplasmic reticulum

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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