Skip Navigation LinksHome > February 2014 - Volume 46 - Issue 2 > Myocardial Dimensions and Hemodynamics during 24-h Ultraendu...
Medicine & Science in Sports & Exercise:
doi: 10.1249/MSS.0b013e3182a64639
Basic Sciences

Myocardial Dimensions and Hemodynamics during 24-h Ultraendurance Ergometry

POKAN, ROCHUS1; OCENASEK, HELMUTH2; HOCHGATTERER, RAINER2; MIEHL, MARTIN1; VONBANK, KARIN3; VON DUVILLARD, SERGE P.4; FRANKLIN, BARRY5; WÜRTH, SABINE6; VOLF, IVO7; WONISCH, MANFRED8; HOFMANN, PETER8

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Abstract

Purpose: This study aimed to evaluate cardiorespiratory and hemodynamic responses during 24 h of continuous cycle ergometry in ultraendurance athletes.

Methods: Eight males (mean ± SD; age = 39 ± 8 yr, height = 179 ± 7 cm, body weight [Wt] = 77.1 ± 6.0 kg) were monitored during 24 h at a constant workload,∼25% below the first lactate turn point at 162 ± 23 W. Measurements included Wt, HR, oxygen consumption (V˙O2), cardiac output (Q), and stroke volume (SV) determined by a noninvasive rebreathing technique (InnocorTM; Innovision, Odense, Denmark). Myocardial dimensions were evaluated using a two-dimensional echocardiogram. [M-mode measurement]-left atrial (LAD), ventricular end-diastolic (LVEDD), and end-systolic diameters (LVESD) were obtained over the left parasternal area. Venous blood samples were analyzed for hematocrit (Hct%), albumin (g·L−1), aldosterone (pg·mL−1), CK, CK-MB (U·L−1), and N-terminal pro–brain natriuretic peptide (NT-proBNP) (pg·mL−1).

Results: HR (bpm) significantly increased (P < 0.01) from 1 h (132 ± 11) to 6 h (143 ± 10) and significantly decreased (P < 0.001) from 6 to 24 h (116 ± 10). V˙O2 and (Q were unchanged during the 24 h. Wt (76.6 ± 5.6 vs 78.7 ± 5.4), SV (117 ± 13 vs 148 ± 19), LVEDD (4.9 ± 0.3 vs 5.6 ± 0.2), and LAD (3.6 ± 0.5 vs 4.3 ± 0.7) significantly increased between 6 and 24 h (P < 0.001). No significant changes were observed for LVESD. Hct (45.1 ± 1.3 vs 41.3 ± 1.2) significantly decreased (P < 0.05) and CK (181 ± 60/877 ± 515), aldosterone (48 ± 17 vs 661 ± 172), and NT-proBNP (23 ± 13 vs 583 ± 449) significantly increased (P < 0.05). The increase in SV (ΔSV) was significantly related to changes in Wt (ΔWt), and HR (ΔHR) and ΔWt were significantly related to ΔLAD and ΔLVEDD.

Conclusion: Our findings suggest that the decrease in HR during 24 h of ultraendurance exercise was due to hypervolemia and the associated ventricular loading, increasing left ventricular diastolic dimensions because of increased SV and LVEDD, resulting in an increase in NT-proBNP.

© 2014 American College of Sports Medicine

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