Impact of habitual sedentary patterns on popliteal artery endothelial-dependent vasodilation in healthy adults

Abstract

Introduction: Acute, laboratory-based bouts of prolonged sitting attenuate lower-limb arterial endothelial-dependent vasodilation. However, the impact of habitual sedentary patterns on popliteal artery endothelial health is unclear. We tested the hypothesis that greater habitual total sedentary time, more time spent in prolonged sedentary bouts, and fewer sedentary breaks would be associated with worse popliteal flow-mediated dilation (FMD) responses. Methods: This cross-sectional study used 98 healthy participants (19–77 years, 53 females) that wore an activPAL monitor on the thigh for 6.4 ± 0.8 days to objectively measure sedentary activity and completed a popliteal ultrasound assessment to determine FMD. Both relative (%baseline diameter) and absolute (mm) FMD were calculated. Using bivariate correlation and multiple regression analyses, we examined if there were relationships between sedentary outcomes and FMD while statistically controlling for any potential confounders. Results: In the multiple regression model, age ( p = 0.006, β = −0.030, 95% CI = −0.051, −0.009) and total time in sedentary bouts > 1 hour ( p = 0.031, β = −0.005, 95% CI = −0.009, −0.001) were independent predictors of relative FMD. Age (β = −0.002, 95% CI = −0.003, −0.001), mean blood flow (β = 0.013, 95% CI = 0.002, 0.024), moderate-intensity physical activity (β = 155.9E−5, 95% CI = 22.4E−5, 289.4E−5), sedentary breaks (β = 0.036, 95% CI = 0.007, 0.066), and total time spent in sedentary bouts > 1 hour (β = −25.02E−5, 95% CI = −47.67E−5, −2.378E−5) were predictors of absolute FMD (all, p < 0.047). All independent outcomes remained significant after partially controlling for all other predictor variables (all, p < 0.031). Conclusions: Habitual prolonged sedentary bouts and sedentary breaks, but not total sedentary time, were predictors of popliteal endothelial-dependent vasodilatory function. The patterns by which sedentary time is accumulated may be more important than the total sedentary time on lower-limb arterial health.

Habitual sedentary time and stationary time are inversely related to aerobic fitness

“…103 participants (52 females) were included in the present study. Some activPAL data have been previously published in a sub-sample of 73 (37 females) that evaluated the impact of habitual activity on peripheral vascular function 14 and the influence of sedentary activity on baroreflex sensitivity. 15 However, the current purpose and statistical analyses (i.e., comparison with aerobic fitness) are independent from these previous reports.…”

Characterization of Detailed Sedentary Postures Using a Tri-Monitor ActivPAL Configuration in Free-Living Conditions

“…Definitions of what angle constitutes sitting versus lying or bent-knee versus straight-legged are unclear, but the angles selected serve as likely reasonable heuristic thresholds in the absence of recommendations. Given the documented physiological differences [ 19 ] and separate international guidelines [ 2 , 3 ] for prolonged versus non-prolonged sedentary time, we examined time spent in sedentary postures separately for prolonged (i.e., >1 h) versus non-prolonged sedentary time (i.e., <1 h). In the absence of a strict definition of what is “prolonged”, 1 h was selected due to the established negative impact of sedentary bouts >1 h on leg blood flow [ 10 ], endothelial function [ 19 ], and arterial blood pressure [ 20 ].…”

Exercise therapy for peripheral artery disease in 2022: Progress and a prediction

“…In this issue of the Journal, two studies in people without PAD demonstrated associations of prolonged uninterrupted sedentary time and fewer breaks during sedentary time with more adverse flow-mediated dilation (FMD) and microvascular or macrovascular function. [4][5][6] A systematic review reported that better aerobic fitness and regular exercise training were associated with more favorable measures of low-flow-mediated constriction, a measure of endothelial vasodilator function and of the decline in conduit artery diameter that occurs during the distal ischemic period of the FMD test. 6 Whether these vascular associations contribute to the biologic pathway for the association of greater sedentary time with higher rates of cardiovascular events requires further study.…”