Intelligence in early adulthood and midlife physical performance in men: The mediating roles of education and physical activity

The objective of this study was to examine whether associations between intelligence in early adulthood and midlife physical performance in men were mediated by education and leisure-time physical activity. Intelligence correlated positively with later education (r = 0.47) and negatively with physical activity (r = − 0.04). We found higher early adult intelligence to be associated with better midlife physical performance for five of the seven measures. Education mediated the association between intelligence and chair-rise and jump height with mediated proportions of 32.4% (95% confidence interval [CI]: 0.21%, 0.43%) and 28.4% (95% CI: 0.17%, 0.39%), respectively. No significant mediating effects of education were seen for sagittal flexibility, postural balance, handgrip strength, or muscle force in the abdomen or lower back. Physical activity was positively associated with physical performance, but because intelligence in early adulthood was inversely associated with physical activity, the indirect effects through physical activity were negative. Overall, education and leisure-time physical activity were not strong mediators of the association between early adult intelligence and midlife physical performance.