The effect of ambient temperature on the running dynamics of professional soccer players during a Brasileirão Série A season.

In recent years, heat stress has represented an increasing risk to players. Thus, studies involving outdoor sports and high temperatures have been conducted on athletes' performances. The purpose of this study was to investigate the effect of ambient temperature on the running dynamics of professional soccer players during a Brasileirão Série A season. Thirty matches were analyzed from 20 professional soccer players during the 2019 Brazilian Elite Championship. To quantify running dynamics during soccer matches, players used GPS device units. Ambient temperatures were classified by the k-means Cluster method into three groups: low (14.1-20.9 C), moderate (21-28.4 C) and high (29.5-35.9 C). Our main finding was that the 1-minute peak of acceleration (p = 0.02) and deceleration distance (p = 0.03) was greater in high temperature situations. In matches with low temperatures, distance in accelerations, decelerations, high-intensity running, and sprinting were greater (p = 0.01-0.02). Significant correlations, negative and low, were found for sprinting (r = - 0.23; p = 0.01), acceleration (r= -0.29; p = 0.001) and deceleration (r= -0.24; r = 0.007) with ambient temperature. These results may be of genuine practical interest to different sectors of soccer, and changes can be made to maintain the intensity and the players' health.