Ice Slurry Ingestion Leads to a Lower Net Heat Loss during Exercise in the Heat
- 1 January 2016
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Medicine & Science in Sports & Exercise
- Vol. 48 (1), 114-122
- https://doi.org/10.1249/mss.0000000000000746
Abstract
To compare the reductions in evaporative heat loss from the skin (Esk) to internal heat loss (Hfluid) induced by ice slurry (ICE) ingestion relative to 37°C fluid and the accompanying body temperature and local thermoeffector responses during exercise in warm, dry conditions (33.5°C ± 1.4°C; 23.7% ± 2.6% relative humidity [RH]). Nine men cycled at approximately 55% V˙O2peak for 75 min and ingested 3.2 mL·kg−1 aliquots of 37°C fluid or ICE after 15, 30, and 45 min of exercise. Metabolic heat production (M-W), rectal temperature (Tre), mean skin temperature (Tsk), whole-body sweat loss (WBSL), local sweat rate (LSR), and skin blood flow (SkBF) were measured throughout. Net heat loss (HLnet) and heat storage (S) were estimated using partitional calorimetry. Relative to the 37°C trial, M-W was similar (P = 0.81) with ICE ingestion; however, the 200 ± 20 kJ greater Hfluid (P < 0.001) with ICE ingestion was overcompensated by a 381 ± 199-kJ lower Esk (P < 0.001). Net heat loss (HLnet) was consequently 131 ± 120 kJ lower (P = 0.01) and S was greater (P = 0.05) with ICE ingestion compared with 37°C fluid ingestion. Concurrently, LSR and WBSL were lower by 0.16 ± 0.14 mg·min−1·cm−2 (P < 0.01) and 191 ± 122 g (P < 0.001), respectively, and SkBF tended to be lower (P = 0.06) by 5.4%maxAU ± 13.4%maxAU in the ICE trial. Changes in Tre and Tsk were similar throughout exercise with ICE compared to 37°C fluid ingestion. Relative to 37°C, ICE ingestion caused disproportionately greater reductions in Esk relative to Hfluid, resulting in a lower HLnet and greater S. Mechanistically, LSR and possibly SkBF were suppressed independently of Tre or Tsk, reaffirming the concept of human abdominal thermoreception. From a heat balance perspective, recommendations for ICE ingestion during exercise in warm, dry conditions should be reconsidered.Keywords
This publication has 34 references indexed in Scilit:
- The Effect of Ice Slushy Ingestion and Mouthwash on Thermoregulation and Endurance Performance in the HeatInternational Journal of Sport Nutrition and Exercise Metabolism, 2013
- Body heat storage during physical activity is lower with hot fluid ingestion under conditions that permit full evaporationActa Physiologica, 2012
- Influence of Beverage Temperature on Exercise Performance in the Heat: A Systematic ReviewInternational Journal of Sport Nutrition and Exercise Metabolism, 2010
- G*Power 3: A flexible statistical power analysis program for the social, behavioral, and biomedical sciencesBehavior Research Methods, 2007
- A three-compartment thermometry model for the improved estimation of changes in body heat contentAmerican Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2007
- Methodological issues in the assessment of skin microvascular endothelial function in humansTrends in Pharmacological Sciences, 2006
- A power primer.Psychological Bulletin, 1992
- Temperature Regulation During ExerciseExercise and Sport Sciences Reviews, 1984
- THERMAL INTERCHANGES BETWEEN THE HUMAN BODY AND ITS ATMOSPHERIC ENVIRONMENT1American Journal of Epidemiology, 1937
- Human CalorimetryJournal of Nutrition, 1935