Macrovascular and microvascular responses to prolonged sitting with and without bodyweight exercise interruptions: A randomized cross-over trial

Exposure to uninterrupted prolonged sitting leads to macro- and microvascular complications, which can contribute to increased cardiovascular disease risk. This study investigated the macrovascular and microvascular responses to 3 h of sitting that was: (i) uninterrupted (CON); and (ii) interrupted every 20 min with 1 min light intensity half squats plus calf raises (EX). Twenty healthy participants (21 [SD: 2] years; 21.5 [SD: 1.6] kg/m 2 ) were recruited to participate in this randomized cross-over trial. Macrovascular function was quantified using brachial–ankle pulse wave velocity (baPWV) and the lower- and upper-limb arterial stiffness index (ASI). Microvascular function was quantified as the medial gastrocnemius tissue oxygen saturation (StO 2 ) area under the curve (AUC) during reactive hyperemia. The baPWV did not significantly change with time ( p = 0.594) or by condition ( p = 0.772). The arm ASI increased by 3.6 (95% CI: 0.7 to 6.6, effect size [ES] = 0.27) with a nonsignificant condition effect ( p = 0.219). There was a significant interaction effect for leg ASI ( p = < 0.001), with ASI increasing (impairment) by 18.7 (95% CI: 12.1 to 25.3, ES = 0.63) for CON and decreasing (improvement) by −11.9 (95% CI: −18.5 to −5.3, ES = 0.40) for EX compared to presitting. Similarly, the AUC decreased (detrimental) by 18% (Δ = −321, 95% CI: −543 to −100, ES = 0.32) for CON and increased by 32% (Δ = 588, 95% CI: 366 to 809, ES = 0.59) for EX. The leg ASI was inversely associated with StO 2 AUC (interclass correlation coefficient: −0.66, 95% CI: −0.51 to −0.77). These preliminary findings suggest that regularly interrupting prolonged sitting with simple bodyweight exercises may help to preserve lower-limb vascular function.