Figure 3. Age, metabolomic fitness score, and peak oxygen uptake (VO₂).

A, Relationship between peak VO₂ and age in the Framingham Heart Study (in the validation subsample). The blue line with overlaying gray confidence intervals represents a Loess spline across the data. B, Joint effects plot depicting the relation between age, the metabolomic fitness score, and peak VO₂. We estimated marginal means for peak VO₂ across age and metabolomic fitness score using a fully adjusted linear model as described (see Methods). The contour lines and heat colors represent model‐estimated peak VO₂. The metabolic VO₂ score is displayed as the mean (0), and each number represents a standard deviation higher or lower than the mean. An illustrative example is shown with an asterisk (*) on the plot; a 60‐year‐old with a metabolomic fitness score ≈1 SD above the mean (ie, 1) has the same peak VO₂ as someone ≈51 years old with a metabolomic fitness score at the mean (ie, 0).