Impact of repeated prolonged exercise bouts on cardiac function and biomarkers.

Middleton, Natalie, Shave, Robert, George, Keith, Whyte, Greg P, Simpson, Richard J, Florida-James, Geraint and Gaze, David (2007) Impact of repeated prolonged exercise bouts on cardiac function and biomarkers. Medicine & Science in Sports & Exercise, 39 (1). pp. 83-90. ISSN 0195-9131

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Purpose: The present study examined the impact of repeated bouts of prolonged (< 60 min) exercise on left ventricular function and cardiac biomarkers.

Methods: Ten athletes completed a 15.3-mile hill run on three consecutive days and were assessed before, immediately after, 1 h after, and 20 h after each bout. Six of the athletes completed a fourth bout. Left ventricular (LV) function was examined echocardiographically using two-dimensional M-mode, Doppler, and flow propagation velocity (Vp). Venous blood samples were analyzed for cardiac biomarkers including cardiac troponin T (cTnT).

Results: Ejection fraction (EF) significantly decreased (P = 0.027) after the third exercise bout compared with baseline (mean +/- SD: 56.3 +/- 4.4 vs 51.3 +/- 5.9%), accompanied by a nonsignificant decrease in systolic blood pressure/end systolic volume (SBP/ESV) ratio. A sustained depression in systolic function 20 h after bout 3 also persisted in the subset who completed a fourth bout, yet this did not reach clinical levels. Significant (P < 0.01) reductions in early to late diastolic filling (E:A) ratio pre-to post-bout 1 (mean +/- SD: 1.9 +/- 0.5 vs 1.4 +/- 0.3) and pre- to post-bout 3(2.0 +/- 0.5 vs 1.3 +/- 0.4) normalized after each 20-h recovery period. A similar pattern of change was observed in Vp. Cardiac troponin T was elevated in four individuals 1 h after bout 1 (range: 0.013-0.125 [mu]g[middle dot]L-1) but was undetectable thereafter except in one athlete.

Conclusion: Repeated bouts of prolonged exercise induce short-term reductions in diastolic filling and a cumulative decrease in systolic function, yet these alterations seem to have minimal clinical or functional impact. Elevated cTnT after the initial bout, but not thereafter, may represent an adaptive response to prolonged exercise.

Item Type: Article
Print ISSN: 0195-9131
Uncontrolled Keywords: Left ventricular function; Cardiac biomarkers; Cardiac troponin
University Divisions/Research Centres: Faculty of Health, Life & Social Sciences > School of Life Sciences
Dewey Decimal Subjects: 500 Science > 570 Life sciences; biology > 572 Biochemistry
500 Science > 570 Life sciences; biology > 571 Physiology & related subjects
600 Technology > 610 Medicine & health > 612 Human physiology
Library of Congress Subjects: Q Science > QP Physiology
Item ID: 1618
Depositing User: RAE Import
Date Deposited: 29 May 2008 15:20
Last Modified: 19 Feb 2013 14:24

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