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Effect of Ice Slurry Ingestion on Cardiovascular Drift and V˙O2max during Heat Stress.
- Source :
-
Medicine & Science in Sports & Exercise . 2019, Vol. 51 Issue 3, p582-589. 8p. - Publication Year :
- 2019
-
Abstract
- External body cooling by fan airflow mitigates the decrease in maximal oxygen uptake (V˙O2max) associated with cardiovascular (CV) drift during cycling in hot conditions. It remains unknown whether internal body cooling via ice slurry ingestion elicits a similar response. Purpose: This study aimed to test the hypothesis that ice slurry ingestion attenuates the magnitude of CV drift and accompanying decrement in V˙O2max during heat stress. Methods: Eight men completed a graded exercise test on a cycle ergometer in 22°C to measure V˙O2max. Then on three separate occasions (in randomly assigned counterbalanced treatment orders), they cycled at 60% V˙O2max in hot conditions (35°C, 40% RH) for 15 min, 45 min with tepid (23°C) fluid ingestion (45FL), or 45 min with ice (−1°C) slurry ingestion (45ICE), followed immediately by measurement of V˙O2max. The purpose of the separate 15- and 45-min trials was to measure CV drift and V˙O2max over the same time interval. Results: The increase in heart rate between 15 and 45 min was twice as large in 45FL (8.6%) compared with 45ICE (4.6%; P = 0.02). Stroke volume declined by 6.2% in 45FL but was maintained with 45ICE (P = 0.02). V˙O2peak decreased from 15 to 45 min by 8.6% and 9.0% in 45FL and 45ICE, respectively, but was not different between conditions (P = 0.79). Conclusion: Although ice slurry ingestion attenuated CV drift more than fluid ingestion, it did not mitigate the decline in V˙O2max. Contrary to previous findings, when ice slurry is ingested, changes in heart rate may not reflect changes in relative metabolic intensity during prolonged exercise in the heat. [ABSTRACT FROM AUTHOR]
- Subjects :
- *REACTIVE oxygen species
*CARDIOPULMONARY system
*CARDIOVASCULAR system physiology
*DEGLUTITION
*DRINKING (Physiology)
*ENERGY metabolism
*EXERCISE tests
*HEART beat
*PHYSIOLOGICAL effects of heat
*HUMIDITY
*ICE
*OXYGEN in the body
*STATISTICAL sampling
*ERGOMETRY
*EXERCISE intensity
*STROKE volume (Cardiac output)
Subjects
Details
- Language :
- English
- ISSN :
- 01959131
- Volume :
- 51
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Medicine & Science in Sports & Exercise
- Publication Type :
- Academic Journal
- Accession number :
- 134732428
- Full Text :
- https://doi.org/10.1249/MSS.0000000000001794