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Hypohydration causes cardiovascular drift without reducing blood volume.
Int J Sports Med. 1994 Feb; 15(2):74-9.IJ

Abstract

To determine the effect of hydration on cardiovascular drift (i.e.; increased heart rate and reduced stroke volume) during exercise in a 21 degrees C environment, nine subjects were studied while cycling at 65% of peak oxygen consumption when euhydrated and while still hypohydrate, following exercise-induced dehydration and a 2 h rest/rehydration period. Subjects dehydrated by exercising in the heat (32 degrees C) until body weight was reduced 2.5%. On two separate occasions following exercise, subjects either received no fluid or ingested a volume of water equal to 100% of the fluid lost during exercise. Following the 2 h rest/rehydration period, 65 +/- 6% of the ingested water was retained and thus the subjects were hypohydrated by 0.9 +/- 0.1%, compared to being hypohydrated by 2.8 +/- 0.1% when no fluid was ingested. Despite these differences in whole body hydration, blood volume during exercise remained at euhydrated levels when hypohydrated by 0.9% and 2.8%. However, the degree of cardiovascular drift was graded in proportion to hypohydration. Compared to the responses when euhydrated, heart rate was elevated 10 +/- 2 and 18 +/- 2 bt/min, whereas stroke volume was reduced 9 +/- 3 and 18 +/- 2 ml/bt, respectively, when hypohydrated by 0.9% and 2.8% during the water and no fluid trials (p < 0.05 for all comparisons). These observations indicate that cardiovascular drift during exercise in a 21 degrees C environment is graded in proportion to hydration and, under these conditions, not due to reductions in blood volume.

Authors+Show Affiliations

Department of Kinesiology and Health Education, University of Texas at Austin 78712.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

8157372

Citation

Heaps, C L., et al. "Hypohydration Causes Cardiovascular Drift Without Reducing Blood Volume." International Journal of Sports Medicine, vol. 15, no. 2, 1994, pp. 74-9.
Heaps CL, González-Alonso J, Coyle EF. Hypohydration causes cardiovascular drift without reducing blood volume. Int J Sports Med. 1994;15(2):74-9.
Heaps, C. L., González-Alonso, J., & Coyle, E. F. (1994). Hypohydration causes cardiovascular drift without reducing blood volume. International Journal of Sports Medicine, 15(2), 74-9.
Heaps CL, González-Alonso J, Coyle EF. Hypohydration Causes Cardiovascular Drift Without Reducing Blood Volume. Int J Sports Med. 1994;15(2):74-9. PubMed PMID: 8157372.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Hypohydration causes cardiovascular drift without reducing blood volume. AU - Heaps,C L, AU - González-Alonso,J, AU - Coyle,E F, PY - 1994/2/1/pubmed PY - 1994/2/1/medline PY - 1994/2/1/entrez SP - 74 EP - 9 JF - International journal of sports medicine JO - Int J Sports Med VL - 15 IS - 2 N2 - To determine the effect of hydration on cardiovascular drift (i.e.; increased heart rate and reduced stroke volume) during exercise in a 21 degrees C environment, nine subjects were studied while cycling at 65% of peak oxygen consumption when euhydrated and while still hypohydrate, following exercise-induced dehydration and a 2 h rest/rehydration period. Subjects dehydrated by exercising in the heat (32 degrees C) until body weight was reduced 2.5%. On two separate occasions following exercise, subjects either received no fluid or ingested a volume of water equal to 100% of the fluid lost during exercise. Following the 2 h rest/rehydration period, 65 +/- 6% of the ingested water was retained and thus the subjects were hypohydrated by 0.9 +/- 0.1%, compared to being hypohydrated by 2.8 +/- 0.1% when no fluid was ingested. Despite these differences in whole body hydration, blood volume during exercise remained at euhydrated levels when hypohydrated by 0.9% and 2.8%. However, the degree of cardiovascular drift was graded in proportion to hypohydration. Compared to the responses when euhydrated, heart rate was elevated 10 +/- 2 and 18 +/- 2 bt/min, whereas stroke volume was reduced 9 +/- 3 and 18 +/- 2 ml/bt, respectively, when hypohydrated by 0.9% and 2.8% during the water and no fluid trials (p < 0.05 for all comparisons). These observations indicate that cardiovascular drift during exercise in a 21 degrees C environment is graded in proportion to hydration and, under these conditions, not due to reductions in blood volume. SN - 0172-4622 UR - https://www.unboundmedicine.com/medline/citation/8157372/Hypohydration_causes_cardiovascular_drift_without_reducing_blood_volume_ L2 - http://www.thieme-connect.com/DOI/DOI?10.1055/s-2007-1021023 DB - PRIME DP - Unbound Medicine ER -