One-hundred seventy-five men in the study were seventy or older. Their HDL-cholesterol showed the same relationship to running distance as in sexagenarians. Specifically, the furthest-running septuagenarians had the highest HDL-cholesterol. This is shown in the scatterplot to the left. Each point represents one runner's weekly running distance (plotted along the horizontal or x axis of the graph) and his HDL-cholesterol (plotted along the vertical or y axis). The line represents the average apparent change in HDL-cholesterol per mile run per week. The second graph shows that the HDL-cholesterol was also highest in those runners who ran the fastest.