Abstract
BACKGROUND: The aims of this study were to (1) analyze the distribution of the player load (PL(TOTAL)) in 3 axes of movement (PL(AP), anterior-posterior; PL(ML), medial-lateral; PL(V), vertical) during elite soccer matches, (2) investigate the effect of playing position on PL-related variables, and (3) explore the association between PL(TOTAL) and distance covered by the players. HYPOTHESIS: Despite different load distribution between axes of movement, PL(TOTAL) 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 PL(V) (P < 0.001; d = 5.41-5.86). Moreover, no effect of playing position on PL(TOTAL), PL(V), PL(ML), or PL(AP) was observed (P > 0.05). Finally, a large correlation was found between PL(TOTAL) and distance covered, and the linear mixed model showed that distance may be predicted by the PL(TOTAL) (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 PL(TOTAL), which is representative of a 3-dimensional analysis, may be adequate for monitoring locomotor demands or accelerometer-derived load. CLINICAL RELEVANCE: Training strategies that focus on the vertical component of match play should be adopted. In addition, given that PL(TOTAL) is an accelerometry-based metric, which combines the accelerations in anterior-posterior, medial-lateral, and vertical planes, strength and conditioning coaches may use this parameter as a measure of total body load.