Local exercise does not prevent the aortic stiffening response to acute prolonged sitting: a randomized crossover trial

Abstract

Prolonged sitting has been shown to promote endothelial dysfunction in the lower legs. Furthermore, it has been reported that simple sitting-interruption strategies, including calf raises, prevent leg endothelial dysfunction. However, it is unclear whether prolonged sitting affects central cardiovascular health, or whether simple sitting-interruption strategies prevent impaired central cardiovascular health. This study sought to answer two questions: in young, healthy adults 1) does prolonged sitting (3 h) lead to increased aortic stiffness, and 2) do intermittent calf raise exercises to prevent pooling prevent aortic stiffening. Twenty young, healthy participants (21.7 ± 2.5 yr, 70% female, 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. There were no condition × 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 versus CALF (P = 0.106). 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.NEW & NOTEWORTHY Although simple strategies, such as fidgeting or calf raises, are sufficient for preserving vascular function in the legs, data from the current study indicate that such strategies are not sufficient for maintaining central cardiovascular health, which is linked to cardiovascular disease.

Keywords: PWV; arterial stiffness; augmentation index; sitting; vascular.