Physical fitness mediates the association between age and cognition in healthy adults

Abstract

Background Physical fitness is an important contributor to healthy aging that improves cognition. Older adults who engage in cardiorespiratory fitness activities show less cognitive decline. Aims To examine whether physical fitness acts as a potential protective mechanism shielding against the negative associations between age and cognition. Specifically, we examined whether physical fitness mediates the relationship between age and processing speed. Methods 114 (M = 63.80, SD = 10.63) senior executives completed a computerized cognitive battery composed of four processing speed tasks. Level of physical fitness was assessed on a treadmill stress test and reported in metabolic equivalents (METs). Results Older age was associated with slower processing speed (r = 0.25, p = 0.007), whereas greater physical fitness was associated with faster processing speed (r = −0.30, p = 0.001). Path analysis indicated that the association between age and processing speed was fully mediated by the level of physical fitness (Indirect effect: β = 0.10, p = 0.008; Direct effect: β = 0.16, p = 0.20). Conclusions and discussion The findings indicate that physical fitness is a strong mediator of the relationship between age and processing speed and imply that physical fitness makes a major contribution to cognitive reserve during the aging process. The results may suggest that the decrease in physical fitness during aging may partially account for slower cognitive processing.