Changes in peak sprint speed during prolonged high-intensity intermittent exercise that simulates team sport play

Coaches and sport scientists tend to agree that it is important for team sports players to be fast. This view is based on the notion that a fast player has a greater chance of getting to the ball or moving into space before a slower opponent, especially during critical periods of a match such as goal- or try-scoring opportunities. There is also evidence from soccer that shows that sprinting speed increases with the standard of the player (Dunbar and Power, 1997: In Science and Football III, edited by T. Reilly, J. Bangsbo and M. Hughes. London: E & FN Spon), such that professionals are faster than semi-professionals and amateurs. Although the value of speed is recognized for these reasons, there is very little information available on the changes in sprint speed during team sport play. The aim of this study was to examine the changes in peak sprint speed over the course of a prolonged high-intensity intermittent exercise protocol that simulated team sport play. After receiving ethical approval from the relevant body at the Central Queensland University, five male recreational team sport players (age 20+3 years, body mass 75+12 kg, maximal oxygen uptake 56+7 ml×kg71×min71; mean+s) provided written informed consent to participate in the study. Drawing on several published time and motion studies, an activity profile representative of team sport play was developed. The activity profile entailed six 15 min periods of intermittent standing (18% of total time, 0% of maximal speed), walking (37% of total time, 20% of maximal speed), jogging (24% of total time, 35% of maximal speed), running (14% of total time, 50% of maximal speed), fast running (4% of total time, 70% of maximal speed) and sprinting (3% of total time, 100% of maximal speed). In total, there were 1866 s sprints and 1863 s sprints over the 90 min protocol. A nonmotorized treadmill (Woodway) was instrumented to allow the measurement of speed and distance. Data were collected at 5000 Hz using an AMLAB data acquisition system and then averaged to provide 20 Hz samples. The players followed the activity profile on a monitor placed at eye level that displayed a target speed together with their current speed. A series of computergenerated audible beeps and verbal commands was used to instruct the players to change speed. The players completed two 45 min periods seperated by an interval of 15 min. The mean and standard deviation peak sprint speeds for each of the six 15 min periods were calculated and analysed by repeated-measures analysis of variance with contrast analysis. The players covered a mean distance of 10,196+403 m; mean peak sprint speed was 24.2+0.8 km×h71 over the 90 min protocol. The mean peak sprint speed for each of the 15 min periods was 25.3+1.0, 24.7+0.8, 24.6+1.2, 24.1+0.9, 23.3+0.7 and 23.3+1.0 km×h71, respectively. Mean peak sprint speed decreased from the first to each of the second (2.4%), fourth (4.7%), fifth (7.9%) and sixth (7.9%) 15 min periods (all P50.05). The results of this study suggest that peak sprint speed decreases progressively during prolonged high-intensity intermittent exercise. This could result from a progressive reduction in phosphocreatine concentration and/or the glycogenolytic rate.