The role of age and physical fitness on the relationship between physical activity and executive function

BackgroundFew studies simultaneously examine the relationship between physical activity, multiple domains of physical fitness (cardiorespiratory fitness, strength, gait speed), and cognition. Our objective was to investigate the association between physical activity and executive function in middle-aged and older adults and examine the extent to which modifiable aspects of physical fitness explain the relationship between physical activity and cognition.MethodsSelf-reported moderate-to-vigorous physical activity, objective measures of cardiorespiratory fitness, muscular strength, gait speed, and executive function were collected from 623 adults within the Human Connectome Project – Aging dataset (ages 36-100 years; mean age = 59.2 years; 57.8% female). Relative importance metrics, multiple regression, and conditional process analysis were used to examine relationships of age, physical activity, and physical fitness with executive function.ResultsGreater physical fitness was related to better executive function performance (β = .28, p < .001). Moderate-to-vigorous physical activity was not associated with executive function (β = -.04, p = .16). These relationships were not dependent on age. There was an indirect relationship between physical activity and executive function through physical fitness (ab = .02, 95% CI: .004 – .04). The strength of this relationship increased with age and was explained primarily by the indirect association of cardiorespiratory fitness with physical activity and executive function.ConclusionsThese data highlight the importance of considering multiple domains of physical fitness in relation to physical activity and cognitive performance in middle aged and older adults, as well as considering different associative strengths among these variables across the adult lifespan.