Author(s): SCHWARZ, E., DUFFIELD, R., ALANIS, A., OLIVEIRA, C., DUARTE MUÑOZ, M., ALANIS, M., LARA, A., COSTA, J., FREEZE, A., MEYER, T., Institution: SAARLAND UNIVERSITY, Country: GERMANY, Abstract-ID: 890

INTRODUCTION:
Playing in hot environmental temperatures is a growing concern for sporting and football organisations worldwide. Therefore, to support player health and minimise performance deterioration during football in the heat, strategies, including cooling procedures and breaks in play, have been proposed; however, investigations in field settings remain scarce (Gouttebarge et al., 2023).
METHODS:
In total, 22 male academy soccer players (age 17 ± 0.8 y) participated in two matches in warm conditions (25.5 ± 2 °C WBGT) and received a cooling intervention (COOL) or a control condition (CON) in a randomised cross-over design. COOL consisted of cold towels (6-9 °C) and cold drinks (5 °C) for 10min of pre-cooling prior to the warmup, 10min before the kick-off, 10min at halftime and for an additional 3min during cooling breaks at 25min into each half. The CON received a placebo drink (17 °C) and no cooling at the same time frames. Core body temperature (Tcore), heart rate (HR), match running performance via gobal positioning system (GPS), sweat loss and fluid intake, rating-of-fatigue (RoF), rating of perceived exertion (RPE), thermal sensation (TS) and perceptions regarding likeability and performance benefits were measured throughout the match-day.
RESULTS:
Players reached a maximum Tcore of 39.2 ± 0.5 °C in COOL, which did not differ from CON (39.1 °C ± 0.5 °C; p ≥ 0.05). Further, there were no differences between conditions for Tcore, HR, GPS, RoF or RPE (p≥0.05), but TS was lower in COOL during respective breaks (p<0.05). Players sweated significantly less in COOL than in CON (2.5 ± 0.5 L vs 2.9 ± 0.6 L) but made up for that by increasing fluid intake (COOL: 1.2 ± 0.3 L; CON: 1.4 ± 0.3 L). Further, players rated the cold towels and cold drinks better than the placebo drinks (p<0.05) and perceived more benefits from COOL than CON (p<0.05).
CONCLUSION:
No physiological or performance benefits were observed for the cooling intervention other than the reduced sweat rate. Given the observed warm but not hot environmental conditions, heat strain remained moderate for both groups and may have impacted the effectiveness of the cooling strategy. Nevertheless, the 3min cooling breaks seemed to attenuate the continuous rise in Tcore described in matches without breaks (Mohr et al., 2011). Future observations are needed to investigate the potential benefits of this strategy in hotter temperatures.

Gouttebarge V et al. 2023. Protective guidelines and mitigation strategies for hot conditions in professional football: starting 11 Hot Tips for consideration. BMJ Open Sport Exerc, 9, doi:10.1136/bmjsem-2023-001608
Mohr M et al. 2012. Physiological Responses and Physical Performance during Football in the Heat. PLoS ONE, 7(6), doi:10.1371/journal.pone.0039202