Within-Match PlayerLoadTM Patterns During a Simulated Soccer Match (SAFT90): Potential Implications for Unit Positioning and Fatigue Management

Barrett, S., Midgley, A.W., Towlson, C., Garrett, A., Portas, M., Lovell, R.

Purpose: This study aimed to evaluate the acute changes in tri-axial accelerometry (PlayerLoadTM; PLVM) and its individual axial planes (anterior-posterior-PlayerLoadTM [PLAP], medial-lateral-PlayerLoadTM [PLML], and vertical-PlayerLoadTM [PLV]) during a standardized 90-minute soccer match-play simulation (SAFT90). Secondary objectives included assessing the test-retest reliability and anatomical location of the devices.
Methods: Semi-professional (n=5) and university (n=15) soccer players completed three trials (one familiarization, two experimental) of SAFT90. PlayerLoadTM and its individual planes were continuously measured using micromechanical-electrical systems (MEMS) positioned at the scapulae (SCAP) and near the center of mass (COM).
Results: No between-half differences in PLVM were observed, but within-half increases were recorded at the COM, particularly during the first half, while only minimal changes were noted at the SCAP. PLVM showed greater contributions from PLV and PLML when derived from the SCAP and COM, respectively. PlayerLoadTM and its individual planes (PLAP, PLML, PLV) were significantly higher at the COM compared to the SCAP. Moderate to high test-retest reliability was observed for PlayerLoadTM and its individual planes at both locations (ICC: 0.80-0.99).
Conclusions: PlayerLoadTM and its individual planes are reliable measures during SAFT90 and can detect within-match changes in movement strategy when the unit is placed at the COM. However, caution is advised when inferring alterations in lower-limb movement strategies from MEMS units positioned at the SCAP.