Intensity matters: vigorous activity is associated with lower pressure-independent arterial stiffness in the UK Biobank.

<h4>Background</h4>Arterial stiffness, a predictor of cardiovascular disease, reflects both structural properties of the arterial wall and load-dependent effects of intra-arterial pressure. Although exercise improves vascular health, its optimal intensity and effects on these stiffness components remain unclear in older adults.<h4>Methods</h4>We analyzed 34 105 UK Biobank participants (mean age 64; 49% female) with finger-derived arterial stiffness index (ASI) and International Physical Activity Questionnaire-assessed activity. ASI was regressed on mean arterial pressure and decomposed into pressure-independent (ASI-PI; residuals) and pressure-dependent (ASI-PD; total minus ASI-PI) components. Multivariable models tested associations with total and intensity-specific MET-minutes, adjusting for demographic, socioeconomic, cardiometabolic, and medication factors.<h4>Results</h4>Higher overall physical activity was associated with lower total ASI (9.45 ± 2.93 for high activity vs 9.72 ± 2.89 for low; p < .001), and lower ASI-PI (-0.01 ± 2.91 for high vs 0.26 ± 2.88 for low vs; p < .001). The association between physical activity and ASI-PD was minimal. Each 1 SD higher total MET was associated with lower ASI-PI (β = -0.094, 95% CI -0.119 to -0.068; p < .001) but not ASI-PD. In intensity-specific models, vigorous activity was consistently associated with lower ASI-PI (β ≈-0.12; p < .001), whereas moderate activity showed modest positive associations, and walking activity was not significantly related. When total activity volume was held constant, vigorous METs were associated with lower ASI-PI, while associations with ASI-PD remained negligible.<h4>Conclusions</h4>Vigorous activity was consistently associated with lower ASI-PI, suggesting beneficial vascular adaptations to exercise beyond its effects on hemodynamic load.