Role of cardiorespiratory fitness in the relation between physical activity and arterial stiffness and hippocampal volume in inactive older adults

Age is one of the major factors that is associated with cognitive decline in older adults. Several physiological changes occur in the body with advancing age. Stiffening of major arteries such as the aorta and carotid arteries is associated with target organ damage to organs that require high blood flow, including the brain. Increased aortic stiffness (AS) dampens the buffering ability of major arteries to regulate blood flow, which leads to microvascular damage in the brain. Another factor that contributes to cognitive decline is atrophy of the hippocampus that is responsible for long-term memory formation. Fortunately, physical activity (PA) that targets improvements in cardiorespiratory fitness (CRF) can attenuate the increase in AS and the decrease in hippocampal volume with advancing age. However, it is unclear whether the CRF level of inactive older adults modifies how PA is related to vascular and brain outcomes relevant to aging.

Participants were divided into the higher and the lower CRF groups. In both groups (n = 70, 66.7 ± 6.3 years), there was no association between light, moderate or vigorous PA and AS or hippocampal volume among inactive middle-aged and older adults and this was not modified by CRF; however, there was a trend for an association between higher vigorous PA (β = -0.373, p = 0.073) and lower cfPWV among those with higher CRF; the association of MAP with cfPWV is blunted by higher CRF in inactive older adults; and higher CRF also appeared to mask the association of age with hippocampal volume.