Effect of Ice Slurry Ingestion on Cardiovascular Drift and VËO2max during Heat Stress.
Med Sci Sports Exerc
; 51(3): 582-589, 2019 03.
Article
en En
| MEDLINE
| ID: mdl-30371546
External body cooling by fan airflow mitigates the decrease in maximal oxygen uptake (VËO2max) 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 VËO2max during heat stress. METHODS: Eight men completed a graded exercise test on a cycle ergometer in 22°C to measure VËO2max. Then on three separate occasions (in randomly assigned counterbalanced treatment orders), they cycled at 60% VËO2max 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 VËO2max. The purpose of the separate 15- and 45-min trials was to measure CV drift and VËO2max 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). VËO2peak 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 VËO2max. 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.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Consumo de Oxígeno
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Estrés Fisiológico
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Volumen Sistólico
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Ingestión de Líquidos
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Frecuencia Cardíaca
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Calor
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Hielo
Tipo de estudio:
Clinical_trials
Límite:
Adolescent
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Adult
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Humans
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Male
Idioma:
En
Revista:
Med Sci Sports Exerc
Año:
2019
Tipo del documento:
Article
Pais de publicación:
Estados Unidos