The effect of a cold environment on physical activity profiles in elite soccer match-play.
In this study, the effect of cold temperature on the physical activity profiles of professional soccer players in official match-play was investigated. Computerised motion-analysis was used to analyse performance in 9 players (4 defenders and 5 midfielders) in 4 temperature ranges: ≤ 5°C (29 matches), 6-10°C (62 matches), 11-20°C (48 matches) and ≥ 21°C (27 matches). Performance was analysed per minute for total distance covered and distance run in 3 categories: 0.0-14.3 km/h (walking/low/moderate); 14.4-19.7 km/h (running); ≥ 19.8 km/h (high-intensity). Results showed that while total distance run per minute was unaffected in colder conditions, midfielders ran significantly shorter distances in warmer temperatures: ≥21°C = 118.7 ± 6.9 m vs. ≤ 5°C=124.2 ± 7.1 m, p < 0.01; 6-10°C = 123.6 ± 6.8 m, p < 0.01; and, 11-20°C = 123.4 ± 5.4, p < 0.05). The total distance covered at 3 intensities and across halves was unaffected by temperature. Similarly, high-intensity efforts across match halves and in the first and final 5-min periods in each half of normal time were unaffected by temperature. In contrast, high-intensity efforts in midfielders across 15-min intervals were affected by temperature with greater distances covered per minute in the 30-45 min period in matches played in temperatures ≤ 5°C vs. the corresponding period in those played in temperatures ≥ 21°C (9.1 ± 3.8 m vs. 6.2 ± 3.0 m, p < 0.05). The present findings generally suggest that physical performance in professional soccer does not decrease in cold temperatures.