Aaron R. CaldwellƗ1, Benjamin T. Harris*1, Megan E. Rosa-CaldwellƗ1, Marcus PayneƗ1, Bryce DanielsƗ1, Kaitlin M. Gallagherǂ1, Matthew S. Ganioǂ1, FACSM. 1University of Arkansas, Fayetteville, AR.

Prolonged sitting creates an atherogenic environment that causes reductions in arterial function. Standing desks have been promoted as a healthy alternative to sitting, but the cardiovascular benefits of standing desks have not been thoroughly investigated. Physical activity, such as taking walking breaks, increases shear stress, and thereby prevents sitting-induced reductions in arterial function. Therefore, walking breaks, even when compared to standing may provide cardiovascular benefits. Purpose: First, to observe changes in arterial stiffness, as assessed by pulse wave velocity (PWV), with a 2 hour bout of standing. Second, to determine if short, intermittent walking bouts provide a comparative advantage to standing alone. Methods: 20 apparently healthy adults (BMI = 22.9 ± 3.2 kg/m2; Age = 21 ± 5 years old) stood for 2 consecutive hours while being assessed for heart rate (HR), mean arterial pressure (MAP), and central (CPWV), upper peripheral (UPWV), and lower peripheral (LPWV) PWV before, during, and after the standing bout. Subjects participated in two trials in a randomized order. In one trial, the subjects stood at a standing desk immobile for 2 hours. In the other trial, subjects performed 5-minute walking breaks after every 25 minutes of standing for a total of two hours of standing with 4 walking breaks. A repeated measures ANOVA utilized for statistical analyses. Results: There was no time by trial interaction for any measure of arterial stiffness (p = 0.82, p = 0.21, and p = 0.15; for CPWV, UPWV, and LPWV respectively). However, from beginning to end of each trial LPWV increased 85 ± 126 cm/s independent of trial (i.e., main effect of time; p < 0.001). There was a non-significant tendency for greater increases in LPWV during the standing (120 ± 142 cm/s) versus the walking trial (50 ± 127 cm/s; p = 0.15). There were no differences regarding HR or MAP (p > 0.05) CONCLUSION: Standing for 2 hours leads to increases in peripheral arterial stiffness. Walking breaks during 2 hours of standing did not significantly attenuate these changes. However, the suggestive evidence (p=0.15) for walking breaks to improve LPWV suggests that future studies should investigate longer duration trials and/or longer walking breaks that are applicable to occupational settings, such as assembly-line work.

Supported by funding from Southwest Center for Occupational and Environmental Health NIOSH Pilot Project Research Training Program

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