Duffield, R, Coutts, AJ, and Quinn, J. Core temperature responses and match running performance during intermittent-sprint exercise competition in warm conditions. J Strength Cond Res 23(4): 1238-1244, 2009-This study investigated the thermoregulatory responses and match running performance of elite team sport competitors (Australian Rules football) during preseason games in a warm environment. During 2 games in dry bulb temperatures above 29°C (>27°C wet bulb globe temperature), 10 players were monitored for core temperature (Tcore) via a telemetric capsule, in-game motion patterns, blood lactate ([La−]), body mass changes, urine specific gravity, and pre- and postgame vertical jump performance. The results showed that peak Tcore was achieved during the final quarter at 39.3 ± 0.7°C and that several players reached values near 40.0°C. Further, the largest proportion of the total rise in Tcore (2.1 ± 0.7°C) occurred during the first quarter of the match, with only small increases during the remainder of the game. The game distance covered was 9.4 ± 1.5 km, of which 2.7 ± 0.9 km was at high-intensity speeds (>14.4 km·h−1). The rise in Tcore was correlated with first-quarter high-intensity running velocity (r = 0.72) and moderate-intensity velocity (r = 0.68), second-quarter Tcore and low-intensity activity velocity (r = −0.90), second-quarter Tcore and moderate-intensity velocity (r = 0.88), fourth-quarter rise in Tcore and very-high-intensity running distance (r = 0.70), and fourth-quarter Tcore and moderate-intensity velocity (r = 0.73). Additional results included mean game [La−] values of 8.7 ± 0.1 mmol·L−1, change in body mass of 2.1 ± 0.8 kg, and no change (p > 0.05) in pre- to postgame vertical jump. These findings indicate that the plateau in Tcore may be regulated by the reduction in low-intensity activity and that pacing strategies may be employed during competitive team sports in the heat to ensure control of the internal heat load.
1School of Human Movement Studies, Charles Sturt University, Bathurst, Australia; 2School of Leisure, Sport and Tourism, University of Technology, Sydney, Australia; and 3Essendon Football Club, Essendon, Australia
Address correspondence to Rob Duffield, email@example.com.