Core body temperature during competition in the heat: National Boys’ 14’s Junior Tennis Championships

Michael F Bergeron ^1*, Kathryn S McLeod ¹ and John F Coyle ²

¹ Medical College of Georgia, United States
² Heart Center of Tulsa, United States

^* To whom correspondence should be addressed. E-mail: mbergero{at}mcg.edu.

Accepted 30 May 2007

Abstract

Objective: To examine on-court core body temperature (TC) and sweat loss, as well as pre- and post-play hydration status, in elite adolescent tennis players during a national championships event in a hot climate.

Methods: Eight healthy, fit, young male tennis players (mean (SD) age: 13.9 (0.9) y; mass: 56.0 (10.7) kg; height: 169.2 (14.7) cm) were evaluated during first-round singles competition at the National Boys’ 14’s Junior Championships in the heat (WBGT 29.6 (0.4) °C). Five of those same players were also evaluated during a same-day doubles match (WBGT 31.3 (0.5) °C).

Results: During doubles (4.37 (0.35) hours after singles), pre-play urine specific gravity (USG) (1.025 (0.002); p=0.06) and total sweat loss (1.9 (0.2) L; p=0.10) tended to be higher before and during doubles, respectively, compared to singles. However, percentage change in body mass (-0.5 (0.3) %) tended to be comparatively less (p=0.08), even though the doubles matches were generally longer (106.6 (11.2) vs. 78.8 (10.9) min; p=0.09) and the degree minutes total was greater (p=0.04). TC increased (p<0.001) during singles and remained elevated, even after 10 minutes following the end of play. Notably, pre-play (singles) USG was strongly associated (p=0.005) with the players’ final TC (38.7 (0.3) °C) recorded at the end of singles play.

Conclusion: Junior tennis players who begin a match not well-hydrated may have progressively increasing thermal strain and a greater risk for exertional heat illness as the match advances.

Key Words: athletes, hydration, player safety, sweating, thermoregulation

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