Is the Endurance Standardized ACWRHMLD or the Underlying Acute and Chronic Components Related to Injuries?

Acute (AW) and chronic (CW) workload imbalances, including their ratio (ACWR), are largely associated with increased injury risk. However, the inclusion of personal endurance performance (EP) in this calculation as a means of improving accuracy has been neglected in previous studies. The aim of this longitudinal observational study was to evaluate the relevance of the high metabolic load distance (ACWRHMLD) to EP in relation to non-contact injuries. Twenty-three German male first division soccer players (age: 24.5 ± 3.5 years; VO2max: 53.7 ± 4.9 mL/min/kg; v4: 15.2 ± 0.9 km/h) were analyzed. Eleven players with non-contact injuries were identified and matched with players without any injuries within the same time interval. Players were monitored using GPS and LPS tracking to calculate ACWRHMLD on a daily basis over the course of one competitive season. Relationships between different endurance performance parameters (v2, v4, vLT, VO2max) and the ACWRHMLD, AW, CW were established for statistical analysis. An area under the curve analysis (AUC) was performed. Based on the four weeks preceding the non-contact injuries, the CW, especially for the last two weeks before the injury, proved to be the most suitable parameter to estimate the risk of injury. The highest significant AUC value (0.81, 95% CI: 0.59–1.00) was calculated for the CW (last week before injury) in relation to the vLT (suitable cut-off: 0.04 km; sensitivity: 78%, specificity: 80%). With regard to the injury rate, the ACWRHMLD seems to be the most appropriate method of calculation, especially for CW related to EP (vLT). The sole use of ACWR, AW, and CW is not recommended.