Skin temperature modifies the impact of hypohydration on aerobic performance
| Autor: | Laura J. Palombo, Robert W. Kenefick, Michael N. Sawka, Brett R. Ely, Samuel N. Cheuvront |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Adult
Male Total work medicine.medical_specialty Hot Temperature Physiology Blood Pressure Cohort Studies Young Adult Oxygen Consumption Animal science Heart Rate Physiology (medical) medicine Humans Cardiac Output Exercise physiology Exercise Skin Blood Volume Dehydration Chemistry Skin temperature Surgery Exercise Test Skin Temperature Heat-Shock Response Body Temperature Regulation Evaporative cooler |
| Zdroj: | Journal of Applied Physiology. 109:79-86 |
| ISSN: | 1522-1601 8750-7587 |
| DOI: | 10.1152/japplphysiol.00135.2010 |
| Popis: | This study determined the effects of hypohydration on aerobic performance in compensable [evaporative cooling requirement (Ereq) < maximal evaporative cooling (Emax)] conditions of 10°C [7°C wet bulb globe temperature (WBGT)], 20°C (16°C WBGT), 30°C (22°C WBGT), and 40°C (27°C WBGT) ambient temperature (Ta). Our hypothesis was that 4% hypohydration would impair aerobic performance to a greater extent with increasing heat stress. Thirty-two men [22 ± 4 yr old, 45 ± 8 ml·kg−1·min−1 peak O2 uptake (V̇o2peak)] were divided into four matched cohorts ( n = 8) and tested at one of four Ta in euhydrated (EU) and hypohydrated (HYPO, −4% body mass) conditions. Subjects completed 30 min of preload exercise (cycle ergometer, 50% V̇o2peak) followed by a 15 min self-paced time trial. Time-trial performance (total work, change from EU) was −3% ( P = 0.1), −5% ( P = 0.06), −12% ( P < 0.05), and −23% ( P < 0.05) in 10°C, 20°C, 30°C, and 40°C Ta, respectively. During preload exercise, skin temperature (Tsk) increased by ∼4°C per 10°C Ta, while core (rectal) temperature (Tre) values were similar within EU and HYPO conditions across all Ta. A significant relationship ( P < 0.05, r = 0.61) was found between Tsk and the percent decrement in time-trial performance. During preload exercise, hypohydration generally blunted the increases in cardiac output and blood pressure while reducing blood volume over time in 30°C and 40°C Ta. Our conclusions are as follows: 1) hypohydration degrades aerobic performance to a greater extent with increasing heat stress; 2) when Tsk is >29°C, 4% hypohydration degrades aerobic performance by ∼1.6% for each additional 1°C Tsk; and 3) cardiovascular strain from high skin blood flow requirements combined with blood volume reductions induced by hypohydration is an important contributor to impaired performance. |
| Databáze: | OpenAIRE |
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