title: Prolonged sitting-induced leg endothelial dysfunction is prevented by fidgeting.
abstract: Prolonged sitting impairs endothelial function in the leg vasculature, and this impairment is thought to be largely mediated by a sustained reduction in blood flow-induced shear stress. Indeed, preventing the marked reduction of shear stress during sitting with local heating abolishes the impairment in popliteal artery endothelial function. Herein, we tested the hypothesis that sitting-induced reductions in shear stress and ensuing endothelial dysfunction would be prevented by periodic leg movement, or "fidgeting." In 11 young, healthy subjects, bilateral measurements of popliteal artery flow-mediated dilation (FMD) were performed before and after a 3-h sitting period during which one leg was subjected to intermittent fidgeting (1 min on/4 min off) while the contralateral leg remained still throughout and served as an internal control. Fidgeting produced a pronounced increase in popliteal artery blood flow and shear rate (prefidgeting, 33.7 ± 2.6 s(-1) to immediately postfidgeting, 222.7 ± 28.3 s(-1); mean ± SE; P < 0.001) that tapered off during the following 60 s. Fidgeting did not alter popliteal artery blood flow and shear rate of the contralateral leg, which was subjected to a reduction in blood flow and shear rate throughout the sitting period (presit, 71.7 ± 8.0 s(-1) to 3-h sit, 20.2 ± 2.9 s(-1); P < 0.001). Popliteal artery FMD was impaired after 3 h of sitting in the control leg (presit, 4.5 ± 0.3% to postsit: 1.6 ± 1.1%; P = 0.039) but improved in the fidgeting leg (presit, 3.7 ± 0.6% to postsit, 6.6 ± 1.2%; P = 0.014). Collectively, the present study provides evidence that prolonged sitting-induced leg endothelial dysfunction is preventable with small amounts of leg movement while sitting, likely through the intermittent increases in vascular shear stress.
authors.affiliation: Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan; Japan Society for the Promotion of Science, Chiyoda, Tokyo, Japan;
authors.forename: Takuma
authors.initials: T
authors.lastname: Morishima
authors.affiliation: Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri;
authors.forename: Robert M
authors.initials: RM
authors.lastname: Restaino
authors.affiliation: Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri;
authors.forename: Lauren K
authors.initials: LK
authors.lastname: Walsh
authors.affiliation: Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri;
authors.forename: Jill A
authors.initials: JA
authors.lastname: Kanaley
authors.affiliation: Kinesiology, University of Texas-Arlington, Arlington, Texas;
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Fadel
authors.affiliation: Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; and Child Health, University of Missouri, Columbia, Missouri padillaja@missouri.edu.
authors.forename: Jaume
authors.initials: J
authors.lastname: Padilla
mesh_terms: D000328:Adult; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D035002:Lower Extremity / Q000098:blood supply*; D008297:Male; D009119:Muscle Contraction; D011150:Popliteal Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011187:Posture; D012039:Regional Blood Flow; D057185:Sedentary Behavior; D013314:Stress, Mechanical; D013997:Time Factors; D018616:Ultrasonography, Doppler, Duplex; D014652:Vascular Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000517:prevention & control*; D014664:Vasodilation
keywords: blood flow; endothelial function; leg movement; physical inactivity; sitting