Effect of Ice Slurry Ingestion on Cardiovascular Drift and V˙O2max during Heat Stress
| Autor: | Ward C Dobbs, Jason Ng, Jonathan E. Wingo |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Adult
Male Hot Temperature Adolescent Drinking Physical Therapy Sports Therapy and Rehabilitation Body Temperature Young Adult 03 medical and health sciences Oxygen Consumption 0302 clinical medicine Animal science Heart Rate Stress Physiological Heart rate Humans Ingestion Orthopedics and Sports Medicine Exercise Cardiovascular drift Chemistry Ice VO2 max Stroke Volume 030229 sport sciences Stroke volume Intensity (physics) Heat stress Exercise Test Slurry Energy Metabolism |
| Zdroj: | Medicine & Science in Sports & Exercise. 51:582-589 |
| ISSN: | 1530-0315 0195-9131 |
| DOI: | 10.1249/mss.0000000000001794 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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