Exploring the Use of Player Load in Elite Soccer Players

Background: The aims of this study were to (1) analyze the distribution of the player load (PLTOTAL) in 3 axes of movement (PLAP, anterior-posterior; PLML, medial-lateral; PLV, vertical) during elite soccer matches, (2) investigate the effect of playing position on PL-related variables, and (3) explore the association between PLTOTAL and distance covered by the players. Hypothesis: Despite different load distribution between axes of movement, PLTOTAL might be used as a body load indicator for all playing positions. Study Design: Longitudinal study. Level of Evidence: Level 3. Methods: Data were collected from elite soccer players using WIMU Pro tracking systems, which included inertial sensors. Results: The axis of movement had a significant effect on the distribution of the load (P < 0.001; conditional R-2 = 0.91), with the greatest contribution from the PLV (P < 0.001; d = 5.41-5.86). Moreover, no effect of playing position on PLTOTAL, P-LV, PLML, or PLAP was observed (P > 0.05). Finally, a large correlation was found between PLTOTAL and distance covered, and the linear mixed model showed that distance may be predicted by the PLTOTAL (conditional R-2 = 0.81; P < 0.001). Conclusion: Differences in load distribution were based on the axis of movement, although playing position had no effect on any variable. The selection of either distance covered, which is representative of a 2-dimensional analysis, or PLTOTAL, which is representative of a 3-dimensional analysis, may be adequate for monitoring locomotor demands or accelerometer-derived load.