Are physical performance and injury risk in a professional soccer team in match-play affected over a prolonged period of fixture congestion?

In this study, the effects of a prolonged period of fixture congestion (8 successive official matches in 26-days) on physical performance and injury risk and severity in a professional soccer team were investigated. Computerised motion-analysis was used to analyse the overall distance covered and that run at light- (0.0-11.0 km•h-1); low- (11.1-14.0 km•h-1); moderate- (14.1-19.7 km•h-1) and high-intensities (≥19.8 km•h-1) for the team as a whole. Distances were measured in metres per minute. Information on match injuries was recorded prospectively. The overall distance covered varied across successive matches (p<0.001) as more distance was run in games 4 and 7 compared to 2 and 3 respectively (126.6±12.3 m•min-1 and 125.0±13.2 m•min-1 vs. 116.0±8.0 m•min-1 and 115.5±11.0 m•min-1). Distance run in light-intensity exercise also varied (p<0.001) as more distance was covered in game 4 versus 1, 2, 3, 5 and 6 (75.5±3.8 m•min-1 vs. 70.6±2.4 m•min-1, 71.8±3.4 m•min-1, 69.3±2.6 m•min-1, 71.5±3.1 m•min-1, and 70.3±2.8 m•min-1) and in game 8 versus game 3 (73.1±3.8 vs. 69.3±2.6 m•min-1) respectively. When comparing match halves, there were no differences across games in overall or high-intensity distance covered and performance in these measures was similar for matches played before, during and after this period. Globally, no difference over the 8 games combined was observed between the reference team and opponents in any of the performance measures whereas the overall distance covered and that in low- (both p<0.001) and high-intensity running (p=0.040) differed in individual games. The incidence of match injury during the congested fixture period was similar to rates reported outside this period but the mean layoff duration of injuries was substantially shorter during the former (p