Reacción a "Small and feasible changes in physical activity are associated with lower mortality risk"

The study led by Professor Ulf Ekelund is an exceptional study that shows that higher levels of moderate to vigorous physical activity have a significant impact on reducing mortality. This study consolidates the existing evidence with an extensive population sample, providing enormous scientific and social relevance in a context in which pharmacological approaches seem to be receiving more attention than the proven relevance of living conditions.

Although the study follows an observational design, limiting causal confirmation, the authors have taken steps to reduce reverse causality bias. In addition, physical activity was measured objectively using accelerometry devices, which provides much greater rigour than other population studies that are often based on self-reported questionnaires. However, its main limitation is that physical activity was only measured at the start of the follow-up, which prevents the analysis from considering possible changes in the physical activity habits of participants over time that could influence the results.

Two comments should also be added to the analysis of this study which, without limiting its quality and relevance, are important for a complete discussion. Firstly, the study only considers the socioeconomic status of participants as an adjustment variable (without delving into the differences), which prevents us from knowing to what extent this effect differs according to inequality. Given the existing evidence, it can be expected that the effect could be greater for populations with low socioeconomic status because their baseline health status is, in general terms, lower than that of those with higher socioeconomic status, which further highlights the relevance of this type of research. Secondly, the study does not include the Spanish population or other southern European countries. This is relevant because there are significant differences in physical activity patterns, eating habits, mortality risk profiles, and social and urban contexts that could show different associations.

Beyond the above, Professor Ekelund's team's study is undoubtedly a wide-ranging piece of research with a highly rigorous methodology that consolidates the evidence of the importance of moderate to vigorous physical activity habits in improving the health of the population and, ultimately, reducing premature mortality among citizens. This highlights the importance of placing actions to promote equitable access for all people at the centre of public policy, especially those with lower socioeconomic status and higher mortality risk.