Cross-sectional and longitudinal models differed in both magnitude and, at younger ages, direction. Each cross-sectional curve was expressed relative to the same age used for its corresponding longitudinal group.
At age 20, males in the classic event were estimated to be 17.1% faster than their age-42 reference cross-sectionally but 4.7% slower longitudinally. The contrast was larger among males in the classic event than in the freestyle event.
Similar trends were observed for females in the classic event.
As with the freestyle analyses, at older ages, longitudinal estimates generally indicated greater deterioration than cross-sectional estimates. These contrasts between cross-sectional and longitudinal analyses show that cross-sectional analyses may not reliably represent within-person age changes in performance.