Acceleration Profiles in Elite Australian Soccer

Abstract

We would like to thank Dr. Wilkinson and Mr. Akenhead for their feedback [4] regarding our recent study describing the activity profiles of elite Australian soccer players [3]. Their comments on accounting for repeated measures (multiple matches) for each player by using a linear-mixed model and covarying for player are correct and we wish to clarify our reasoning for the statistical approach used in our study. We acknowledge that the suggested approach of mixed method modelling, covarying for player would eliminate one source of bias within the data. However, this approach assumes that each player’s activity is most dependent on the player themselves. In team sport a player’s activity is inherently associated with their direct opponent’s activity. Whilst obviously the player is an important variable to consider in an analysis, we suggest that the activity of a player is influenced by the tactics of their team, the opposition team and most importantly their direct opponent. Thus the activity profile of a given individual will vary greatly from match-to-match. For example in our study, match-to-match variation in accelerations on average for each player ranged from 38 to 84 for midfielders, 46 to 74 for central defenders and 47 to 71 for forwards. Further investigation of the data also reveals that high performing players one week did not necessarily perform better than their team-mates in following weeks (in essence their ranking in the team was also variable).