Author(s): PAGE, J., MALVERN, J.; HEFFERNAN, S.; KILDUFF, L.; PEEL, J.; VASSALLO, C., WALDRON, M, Institution: SWANSEA UNIVERSITY, Country: UNITED KINGDOM, Abstract-ID: 2493

INTRODUCTION:
Motorsport driver-athletes are often exposed to extreme thermal environments, with cockpit temperatures reportedly reaching 60°C [1]. Personal protective clothing renders evaporative heat loss largely ineffective and exacerbates thermal strain. Ingestion of an ice slurry prior to exercise can expand the heat storage window, improving tolerance to rising core temperature (Tcore) [2] and suppressing the sweat response [3]. Sodium citrate (SC) prior to exercise promotes fluid retention, contributing to hyperhydration (HH) [4]. Both offer potential value as pre-race strategies to mitigate risk of thermal strain and hypohydration in driver-athletes exposed to high cockpit temperatures [5]. This study aimed to determine the effect of slurry ingestion and SC-induced HH alone or in combination on thermoregulatory responses to a simulated driving task in a hot environment.
METHODS:
Eight healthy, non-acclimated individuals (24±2 yrs) completed four trials in a double-blind, randomised, crossover design. Participants ingested 300 mg/kg SC or placebo (PLA) with 25 mL/kg water 150 min prior to a 60-min racing simulation in an environmental chamber (35°C, 30% RH). During the final 30 min pre-driving, participants consumed 10 g/kg ice slurry or no slurry. Simulated driving was conducted while wearing full fire-retardant racing attire (race suit, gloves, boots, balaclava and helmet). Change in core temperature (delta Tcore) and plasma volume (PV) were assessed pre- and post-HH/slurry. During the 60-min driving task, delta Tcore, end Tcore, PV, whole-body sweat rate (WBSR), back and arm local sweat rate (LSR) were determined.
RESULTS:
Ice slurry ingestion alone reduced pre-driving Tcore (-0.45±0.28°C) to a greater extent than no slurry + PLA (-0.03±0.11°C, P<0.001) and no slurry + SC (-0.06±0.09°C, P<0.001). Reductions in pre-driving Tcore following co-ingestion of slurry + SC (-0.23±0.08°C) were not statistically different from any other condition (P>0.05). Across 60-min simulated racing, delta Tcore was greater following ingestion of slurry + PLA (0.35±0.18°C, P=0.008) and slurry + SC (0.37±0.18°C, P=0.003) compared to no slurry + PLA (0.15±0.15°C) but there were no condition effects for end Tcore (P>0.05). There were no condition effects for WBSR (P=0.87), back (P=0.53) and arm (P=0.88) LSR or LSR-deltaTcore ratio (P=0.25) during simulated driving. There were no condition effects for PV (P>0.05).
CONCLUSION:
Ice slurry ingestion transiently reduced Tcore prior to simulated driving in the heat but did not suppress the sweat response, nor did it translate to lower end-driving Tcore. SC-induced HH provided no additional thermophysiological benefit, therefore the application of these pre-race cooling strategies warrant further investigation before use within motorsport.

[1] Del Rosso et al,2016,Jour Stren & Cond Res;[2] Jay & Morris,2018,Sports Med;[3] Siegel et al,2010,Med Sci Sports Exerc;[4] Siegler et al,2021,Int jour sport nutr and exerc metab;[5] Reid & Lightfoot, 2019, Med Sci Sports.