Relative, individualized, or normalized? A conceptual clarification of running speed terminology in soccer

There is inconsistency in quantifying, defining and interpreting running speed nomenclature in soccer. In particular, the terms "relative", "individualized", and "normalized" are frequently used interchangeably, despite referring to different conceptual and methodological approaches. This lack of clarity may affect the interpretation of running intensity and limit comparability across studies. Therefore, the aim of this paper is to clarify the conceptual distinctions between these terms in the context of soccer performance analysis. We distinguish between absolute thresholds (e.g., a value expressed without context), relative comparisons based on external references, individualized reference values (e.g., a value obtained during treadmill protocol), and normalized metrics that express running speed as a proportion of an individual's physiological characteristic (e.g., percentage of the maximum speed). Using theoretical arguments and applied examples, it was shown that many approaches described as "relative" or "individualized" correspond, in methodological terms, to normalization. Moreover, it was also highlight that the interpretation of normalized intensity depends on the reference used, as different tests (e.g., linear sprint tests vs. intermittent field tests) reflect distinct physiological and mechanical characteristics. Clarifying these distinctions is important to improve methodological rigor and consistency in the analysis of running demands. By contextualizing running demands according to each athlete's maximum speed registered until the point of monitoring, this approach may better approximate the normalized locomotor stimulus imposed by a given training load, in relation to the player's true, albeit inherently unknown, maximal potential exposure. Future research should adopt more precise terminology and clearly report the reference values and scaling procedures used when quantifying running demands in soccer.