Cardiovascular adaptations to 10 days of cycle exercise

Constance M. Mier, Michael J. Turner, Ali A. Ehsani, Robert J. Spina

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Abstract

We hypothesized that 10 days of training would enhance cardiac output (CO) and stroke volume (SV) during peak exercise and increase the inotropic response to β-adrenergic stimulation. Ten subjects [age 26 ± 2 (SE) yr] trained on a cycle ergometer for 10 days. At peak exercise, training increased O2 uptake, CO, and SV (P < 0.001). Left ventricular (LV) size and function at rest were assessed with two-dimensional echocardiography before (baseline) and after atropine injection (1.0 rag) and during four graded doses of dobutamine. LV end-diastolic diameter increased with training (P < 0.02), whereas LV wall thickness was unchanged. LV contractile performance was assessed by relating fractional shortening (FS) to the estimated end- systolic wall stress (σ(ES)). Training increased the slope of the FS-σ(ES) relationship (P < 0.05), indicating enhanced systolic function. The increase in slope correlated with increases in CO (r = -0.71, P < 0.05) and SV (r = - 0.70, P < 0.05). The increase in blood volume also correlated with increases in CO (r = 0.80, P < 0.01) and SV (r = 0.85, P < 0.004). These data show that 10 days of training enhance the inotropic response to β-adrenergic stimulation, associated with increases in CO and SV during peak exercise.

Original languageEnglish
Pages (from-to)1900-1906
Number of pages7
JournalJournal of Applied Physiology
Volume83
Issue number6
DOIs
StatePublished - Dec 1997

Keywords

  • Cardiac output
  • Left ventricular function
  • Short-term training
  • Stroke volume

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