Walking Energetics And Cerebral Vascular Health

PURPOSE: White matter hyperintensities (WMHs) are markers of cerebral small vessel disease, increase with age, and contribute to cognitive and motor function decline. Energy costs for mobility worsen with age, as the energetic cost of walking increases and energetic capacity declines. We examined the cross-sectional associations of multiple measures of walking energetics with WMHs in mid-to-late-aged adults from the Baltimore Longitudinal Study of Aging. METHODS: A total of 601 cognitively unimpaired adults (mean age 66.9 ± 15.3 years, 54% women) underwent brain magnetic resonance imaging scans and completed two walking energy expenditure assessments with metabolic measurement (V̇O2), to derive three measures: standardized slow-paced V̇O2 (ml/kg/min), peak-paced V̇O2 (ml/kg/min), and a ratio of slow-to peak-paced V̇O2 (“cost-to-capacity ratio”). T1-weighted scans and FLAIR images were used to quantify WMHs. A series of linear regression models that controlled for demographics, body composition, and comorbid conditions were performed to test the associations between walking energetics and WMHs. To improve the interpretability, we report standardized beta coefficients. RESULTS: In unadjusted models, lower slow-paced V̇O2, higher peak-paced V̇O2, and lower cost-to-capacity were each associated with less WMHs (all p < .0001). All associations remained significant after adjusting for total WM volume, age, sex, race, education, systolic blood pressure, height, body composition, and comorbid conditions (Model 1). After additional adjustment for usual gait speed (Model 2), lower slow-paced V̇O2 (B = .07; p = .030), higher peak-paced V̇O2 (B = -.10; p = .007), and lower cost-to-capacity ratio (B = .12; p < .0001), each remained significantly associated with lower WMH volume. The cost-to-capacity ratio, which describes the percentage of capacity required for ambulation, was the walking energetic measure most strongly associated with WMHs. CONCLUSIONS: Efforts to maintain aerobic capacity and walking efficiency may preserve white matter structure throughout mid-to-late life. Longitudinal research investigating additional markers of cerebral small vessel disease is needed to determine the temporality and specificity of the association between walking energetics and cerebral vascular health. K01AG080122