The Within-Match Patterns of Locomotor Efficiency During Professional Soccer Match Play: Implications for Injury Risk

Barrett, S., Midgley, A., Reeves, M., Joel, T.

Objectives: The primary aim of this study was to investigate within-match patterns of locomotor efficiency in professional soccer, as determined by the ratio between tri-axial accelerometer data (PlayerLoadTM) and locomotor activities. Additionally, between-match variability and determinants of PlayerLoadTM during match play were assessed.
Design: This study employed a single-cohort observational design.
Methods: Tri-axial accelerometer data (PlayerLoadTM) were recorded during 86 competitive soccer matches involving 63 English championship players (574 match observations). Accelerometer data accumulated (PlayerLoad Vector Magnitude [PLVM]) from the individual-component planes of PlayerLoadTM (anterior-posterior PlayerLoadTM [PLAP], medial-lateral PlayerLoadTM [PLML], and vertical PlayerLoadTM [PLV]), along with locomotor activity (Total Distance Covered [TDC]), were determined in 15-minute segments. Locomotor efficiency was calculated using the ratio of PLVM and TDC (PlayerLoadTM per meter). The proportion of variance explaining within-match trends in PLVM, PLAP, APML, APv, and TDC was determined with respect to matches, individual players, and positional role.
Results: PLVM, PLAP, APML, APv, and TDC decreased after the initial 15-minute match period (P=0.001; η^2 = 0.22-0.43, large effects). PL:TDC increased in the last 15 minutes of each half (P=0.001; η^2 = 0.25, large effect). The variance in PLVM during soccer match-play was explained by individual players (63.9%; P=0.001) and between-match variation (21.6%; P=0.001), but not positional role (14.1%; P=0.364).
Conclusions: Locomotor efficiency is lower during the latter stages of each half of competitive soccer match-play, a trend synonymous with observations of increased injury incidence and fatigue in these periods. Locomotor efficiency may be a valuable metric to identify fatigue and heightened injury risk during soccer training and match-play.

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