Lara A Carlson
University of New England, Maine, USA
Title: Hydration Status and Thermoregulatory Responses in Drivers During Competitive Racing
Biography
Biography: Lara A Carlson
Abstract
Stock car drivers are exposed to high ambient temperatures prior to-, and during competition, further complicated by the fact that they are encapsulated in protective clothing; however, the hydration status of these drivers has not been determined. Purpose: To quantify the degree of fluid losses during a competitive event in hot conditions. Methods: Nine male stock car drivers (30  9 yr, 178  3 cm, 83  19 kg) were studied during a Pro Series Division NASCAR race. Sweat rate (SR) and dehydration was determined via nude body weights (BW) pre- and post-race. SR calculations included ~40 min of pre-race activity and ~20 min or racing. Results: Urine loss was considered fluid loss and BW was corrected for fluid and food intake. Pre-race BW was 81.5  18.5 kg and decreased to 81.1  18.5 kg post-race (p=0.001). BW loss post-race was 0.77  0.3% and average sweat rate was 0.63  0.4 L• h-1. Intestinal core increased from 38.0  0.4oC to 38.5  0.4oC post-race (p=0.001). Skin temperature increased from 35.8  0.8oC 36.9  0.8oC post-race (p=0.001), whereas the core-to-skin temperature gradient narrowed from 2.2  0.9oC to 1.6  0.9oC, pre to post-race (p=0.001). Heart rates (HR) post-race were 89  0.0% of the drivers’ age-predicted maximum HR. Conclusion: Fluid losses during competitive racing can be significant, particularly when SR is extrapolated to longer duration events. Without a fluid replacement strategy, fluid losses for these drivers may exceed 3% BW and could negatively impact driving performance.