LAUSR

Prolonged sitting has been shown to promote endothelial dysfunction in the lower legs. Further, it has been reported that simple sitting-interruption strategies, including calf raises, prevent leg endothelial function. However, it is unclear whether prolonged sitting affects central cardiovascular health, or whether simple sitting interruption strategies prevent impaired central cardiovascular health. PURPOSE This study sought to answer two questions: in young, healthy adults (i) does prolonged sitting (3h) lead to increased aortic stiffness? and (ii) do intermittent calf raise exercises to prevent pooling, also prevent aortic stiffening? METHODS Twenty young, healthy participants (21.7±2.5 y, 70% F, 25.5±6.1 kg/m2) were randomized to 3 h of sitting with (CALF) or without (CON) 10 calf raises every 10 min. Aortic stiffening (carotid-femoral pulse wave velocity, PWV) was measured in the supine position pre- and post-sitting. Venous pooling during sitting was estimated with total hemoglobin (tHB) concentration using near-infrared spectroscopy. RESULTS There were no condition x time interactions. Following 3 h of sitting, PWV significantly increased (0.30±0.46 m/s, p <0.001). There was no condition effect for PWV (p=0.694), indicating the intermittent calf rises did not preserve central cardiovascular health. tHb was not significantly affected by sitting (p=0.446) but was 1.9 μM higher for CON vs. CALF (p=0.106). CONCLUSIONS Sitting increases aortic stiffness in young, healthy individuals, a process that may be influenced by lower extremity blood pooling. Calf raises, which have been reported to preserve vascular function in the legs, do not appear to provide sufficient stimulus for maintaining central cardiovascular health.