Relationship between cardiorespiratory fitness and blood pressure in young adults: a mediation analysis of body composition.

High blood pressure levels are among the most important cardiovascular disease risk factors and are influenced by physical fitness and body composition. However, the degree to which obesity may attenuate or modify the beneficial effects of physical fitness on blood pressure levels in young adults is uncertain. Thus, the aim of this study was to analyze whether body composition is a mediator between cardiorespiratory fitness (CRF) and blood pressure levels in young adults. This work was a cross-sectional study involving first-year college students (n=386) at the University Campus of Cuenca (Spain). We measured weight, height, waist circumference, fat mass percentage (by densitometry), systolic and diastolic blood pressure and CRF levels (by a 20 m shuttle run test). Partial correlation coefficients were estimated to examine the relationships among adiposity variables, CRF and blood pressure variables, controlling for age and sex. ANCOVA models were conducted to explore differences in blood pressure levels across adiposity and CRF categories. Hayes's PROCESS macro was used for the simple mediation analysis. The indirect effect and Sobel test were significant (P<0.001), confirming that all body composition variables mediate between CRF and all of the included blood pressure variables. All body composition variables acted as mediators between CRF and blood pressure. These results highlight the importance of maintaining a healthy body composition to prevent hypertension in young adults.