AUTHOR=Bowden Davies Kelly A. , Norman Juliette A. , Thompson Andrew , Mitchell Katie L. , Harrold Joanne A. , Halford Jason C. G. , Wilding John P. H. , Kemp Graham J. , Cuthbertson Daniel J. , Sprung Victoria S. 

TITLE=Short-Term Physical Inactivity Induces Endothelial Dysfunction

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.659834

DOI=10.3389/fphys.2021.659834

ISSN=1664-042X

ABSTRACT=<sec><title>Objective</title><p>This study examined the effects of a short-term reduction in physical activity, and subsequent resumption, on metabolic profiles, body composition and cardiovascular (endothelial) function.</p></sec><sec><title>Design</title><p>Twenty-eight habitually active (≥10,000 steps/day) participants (18 female, 10 male; age 32 ± 11 years; BMI 24.3 ± 2.5 kg/m<sup>2</sup>) were assessed at baseline, following 14 days of step-reduction and 14 days after resuming habitual activity.</p></sec><sec><title>Methods</title><p>Physical activity was monitored throughout (SenseWear Armband). Endothelial function (flow mediated dilation; FMD), cardiorespiratory fitness (<inline-formula><mml:math id="INEQ1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mtext>V</mml:mtext><mml:mo>.</mml:mo></mml:mover><mml:mo>⁢</mml:mo><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math></inline-formula> peak) and body composition including liver fat (dual-energy x-ray absorptiometry and magnetic resonance spectroscopy) were determined at each assessment. Statistical analysis was performed using one-way within subject’s ANOVA; data presented as mean (95% CI).</p></sec><sec><title>Results</title><p>Participants decreased their step count from baseline by 10,111 steps/day (8949, 11,274; <italic>P</italic> &lt; 0.001), increasing sedentary time by 103 min/day (29, 177; <italic>P</italic> &lt; 0.001). Following 14 days of step-reduction, endothelial function was reduced by a 1.8% (0.4, 3.3; <italic>P</italic> = 0.01) decrease in FMD. Following resumption of habitual activity, FMD increased by 1.4%, comparable to the baseline level 0.4% (–1.8, 2.6; <italic>P</italic> = 1.00). Total body fat, waist circumference, liver fat, whole body insulin sensitivity and cardiorespiratory fitness were all adversely affected by 14 days step-reduction (<italic>P</italic> &lt; 0.05) but returned to baseline levels following resumption of activity.</p></sec><sec><title>Conclusion</title><p>This data shows for the first time that whilst a decline in endothelial function is observed following short-term physical inactivity, this is reversed on resumption of habitual activity. The findings highlight the need for public health interventions that focus on minimizing time spent in sedentary behavior.</p></sec>