Supplementary Material for: Inflammation and Perceived Social Support in Elite Athletes (A Quantile Regression Approach)

Introduction: Inflammation and social relationships are bidirectionally linked, yet evidence in young, non-clinical populations is scarce. Given that elite athletes face continuous immune challenges and unique social conditions, this cohort provides a model to explore this association. Methods: Several quantile regressions were computed across 422 elite athletes. To account for both the magnitude of inflammation and the characteristics of social relationships, quantiles were determined based on the concentrations of TNF-α, IL-6, and the Systemic Inflammatory Response Index (SIRI) as well as on measures of the total, general perceived social support. The corresponding predictors were social support and the inflammatory markers. Results: A higher total, general perceived social support predicted a significantly lower SIRI in the lowest quartile as well as lower concentrations of the cytokines in the highest three quartiles. Effects were small but robust. Moreover, higher inflammation predicted a lower total, general perceived social support in elite athletes, when the perceived social support was relatively moderate. However, this effect was not robust when covariates, such as urea or the living situation, were added to the models. Conclusion: Results suggest that elite athletes’ social relationships are a small yet important factor influencing the inflammatory response. The social support elite athletes perceive, however, appears to be influenced by inflammation only under specific biopsychosocial conditions.