TY - JOUR

T1 - Dehydration reduces left ventricular filling at rest and during exercise independent of twist mechanics

AU - Stöhr, Eric J.

AU - González-Alonso, José

AU - Pearson, James

AU - Low, David A.

AU - Ali, Leena

AU - Barke, Horace

AU - Shave, Rob

PY - 2011/9/1

Y1 - 2011/9/1

N2 - The purpose of this study was to determine whether the reduction in stroke volume (SV), previously shown to occur with dehydration and increases in internal body temperatures during prolonged exercise, is caused by a reduction in left ventricular (LV) function, as indicated by LV volumes, strain, and twist ("LV mechanics"). Eight healthy men [age: 20 ± 2, maximal oxygen uptake (VO 2max): 58 ± 7 ml kg -1min -1] completed two, 1-h bouts of cycling in the heat (35°C, 50% peak power) without fluid replacement, resulting in 2% and 3.5% dehydration, respectively. Conventional and two-dimensional speckle-tracking echocardiography was used to determine LV volumes, strain, and twist at rest and during one-legged knee-extensor exercise at baseline, both levels of dehydration, and following rehydration. Progressive dehydration caused a significant reduction in end-diastolic volume (EDV) and SV at rest and during one-legged knee-extensor exercise (rest: δ- 33 ± 14 and δ- 21 ± 14 ml, respectively; exercise: δ- 30 ± 10 and δ- 22 ± 9 ml, respectively, during 3.5% dehydration). In contrast to the marked decline in EDV and SV, systolic and diastolic LV mechanics were either maintained or even enhanced with dehydration at rest and during knee-extensor exercise. We conclude that dehydration-induced reductions in SV at rest and during exercise are the result of reduced LV filling, as reflected by the decline in EDV. The concomitant maintenance of LV mechanics suggests that the decrease in LV filling, and consequently ejection, is likely caused by the reduction in blood volume and/or diminished filling time rather than impaired LV function.

AB - The purpose of this study was to determine whether the reduction in stroke volume (SV), previously shown to occur with dehydration and increases in internal body temperatures during prolonged exercise, is caused by a reduction in left ventricular (LV) function, as indicated by LV volumes, strain, and twist ("LV mechanics"). Eight healthy men [age: 20 ± 2, maximal oxygen uptake (VO 2max): 58 ± 7 ml kg -1min -1] completed two, 1-h bouts of cycling in the heat (35°C, 50% peak power) without fluid replacement, resulting in 2% and 3.5% dehydration, respectively. Conventional and two-dimensional speckle-tracking echocardiography was used to determine LV volumes, strain, and twist at rest and during one-legged knee-extensor exercise at baseline, both levels of dehydration, and following rehydration. Progressive dehydration caused a significant reduction in end-diastolic volume (EDV) and SV at rest and during one-legged knee-extensor exercise (rest: δ- 33 ± 14 and δ- 21 ± 14 ml, respectively; exercise: δ- 30 ± 10 and δ- 22 ± 9 ml, respectively, during 3.5% dehydration). In contrast to the marked decline in EDV and SV, systolic and diastolic LV mechanics were either maintained or even enhanced with dehydration at rest and during knee-extensor exercise. We conclude that dehydration-induced reductions in SV at rest and during exercise are the result of reduced LV filling, as reflected by the decline in EDV. The concomitant maintenance of LV mechanics suggests that the decrease in LV filling, and consequently ejection, is likely caused by the reduction in blood volume and/or diminished filling time rather than impaired LV function.

KW - Diastole

KW - Hypohydration

KW - Torsion

KW - Untwisting

UR - http://www.scopus.com/inward/record.url?scp=80053024638&partnerID=8YFLogxK

U2 - 10.1152/japplphysiol.00528.2011

DO - 10.1152/japplphysiol.00528.2011

M3 - Article

C2 - 21700893

AN - SCOPUS:80053024638

VL - 111

SP - 891

EP - 897

JO - Journal of applied physiology

JF - Journal of applied physiology

SN - 8750-7587

IS - 3

ER -