The Relationship Between Training Volume and BMI in the Expression of Running Performance in Runners: A Mediation Model

PurposeThe relationships between anthropometric and training variables with running performance were previously investigated. However, it is possible that through the moderating role of anthropometric variables, the magnitude of the relationship between training and performance may be changed. The purpose of this study was to estimate the mediation role of body mass index (BMI) in the relationship between training volume and running performance among non-professional runners, taking into account sex and age category.MethodsThe sample comprised 1151 non-professional road runners (61.8% male), aged 18-72 years. Information about sex, age, body mass (kg), body height (cm), running pace, motivation for running, training volume and frequency were obtained through an online questionnaire. Taking into account athletes' age, they were split into two age categories: "until 34 years" (adult runners) and ">= 35 years" (master athletes). A mediation analysis was computed in Macro Process (SPSS 26), considering sex and age category. BMI was the mediating variable, while training volume/week was used as independent variable, and running pace was considered as dependent variable.ResultsFor both sexes and age categories, a significant association between training volume on running pace was observed [male adult: beta = - 0.67; 95% CI (- 1.04 to - 0.53); male master: beta = - 0.241; 95% CI (- 0.44 to - 0.26); female adult: -0.83; 95% CI (- 1.25 to - 0.41); female master: - 0.76; 95% CI (- 1.09 to - 0.44)], as well the association between training volume and BMI; and running BMI and running pace. Except for female adult runners, a mediation effect of BMI was observed.ConclusionThe present study showed that BMI mediated the association between training volume and running pace in non-professional runners of different sexes and age categories. On the other hand, a small influence of training volume on the expression of BMI was found.