Collective external load and competitive success in elite international soccer: A PCA-derived synthetic Index from the 2024 Copa America

Abstract

This study developed a synthetic index of collective physical performance to analyse match running profiles of national teams during the 2024 Copa America. Five external load variables (total distance, high-intensity running distance, sprint distance, accelerations, and decelerations), obtained from official optical tracking reports for 32 matches of 16 teams, were expressed per minute and normalized to the tournament maximum. Principal component analysis based on the covariance matrix was performed on mean-centred data. Sampling adequacy was confirmed (KMO=0.815; Bartlett´s test: χ² = 200.45; df = 10; p < 0.001). The first principal component (PC1) explained 74.4% of variance and was retained as the team synthetic index. Sprint and high-intensity running showed the highest loadings, whereas total distance showed minimal loading. PC1 scores varied substantially between teams and across competition phases, with heterogeneous patterns observed between group and knockout stages and notable within-team variability across matches. Uruguay national team achieved the highest PC1 score, while Argentina national team maintained negative PC1 values throughout the tournament despite ultimately winning the championship. The association between mean PC1 and tournament performance percentage was weak and non-significant (Spearman ρ = 0.20, 95% CI [-0.38, 0.64], p = 0.46). These findings indicate that collective physical loads differ across teams and vary across competition phases, while their association with competitive success appears limited and inconclusive. The proposed synthetic index provides a parsimonious and interpretable summary of external load that may assist practitioners in contextualising collective physical demands across matches within the multifactorial structure of elite soccer performance.