Validation Limitations

The study lacked prospective injury ground truth, so predictive injury metrics could not be computed. Further research is needed to establish EPCC-14's external, concurrent, and discriminative validity. Synthetic augmentation cannot replace prospective biological validation despite regularization and diagonal covariance. Generalization remains unproven because the real cohort was small and limited to male amateur soccer players from one regional context. Individuals aged 70 to 85 years are not represented in the current participant dataset. Ceiling effects remain a concern for EPCC-14 because some respondents achieved maximum scores. The online cross-sectional Prolific sample limits certainty about how EPCC-14 will perform in routine clinical settings. The technology has not been validated for individuals aged 70 to 85 years. The sample over-represented university-educated participants, although the final measure did not show differential item functioning by education. The framework has not yet integrated external load metrics, subjective measures, medical records, or GPS data. A short fixed questionnaire may be less sensitive among patients reporting very high person-centred care…