title: Associations of Reducing Sedentary Time With Vascular Function and Insulin Sensitivity in Older Sedentary Adults.
abstract: BACKGROUND
  We previously reported increased moderate-intensity (3-6 metabolic equivalents (METs)) physical activity (PA) reverses aging-associated vascular endothelial dysfunction, a surrogate marker of cardiovascular risk. Whether reductions in sedentary time alone contribute to this improvement is unknown.
  
  
  METHODS
  Data from 96 adults (aged ≥50 years) enrolled in a randomized control trial evaluating a 12-week intervention to increase PA in sedentary individuals were analyzed. Amount and intensity of activity were measured pre- and post-intervention by step count and accelerometry. Subjects were divided into 3 categories based on change in sedentary activity (<1. 5 METs): (i) ≥5% reduction in sedentary time, (ii) 0-4.99% reduction, and (iii) increase sedentary time. Vascular endothelial function was measured by brachial artery flow-mediated dilation (FMD%) pre- and post-intervention.
  
  
  RESULTS
  Sedentary time decreased overall (P = 0.001), with a 101-minute decrease in category 1 (N = 27, P < 0.001), a 42-minute decrease in category 2 (N = 29, P = 0.003), and a 44-minute increase in category 3 (N = 40, P = 0.02). While FMD% increased in the entire study population (P = 0.008) over 12 weeks, no differences were observed between the categories (P = 0.73). In category 1, FMD% improvement was associated achievement of ≥20 minutes/day of moderate intensity PA in bouts ≥ 10 minutes in length.
  
  
  CONCLUSIONS
  Reductions of up to 100 minutes of sedentary time per day over 12 weeks was not significantly associated with improved vascular endothelial function in older adults. FMD% was significantly higher among those with lower sedentary behavior and concomitant moderate-intensity PA of ≥20 minutes/day in bouts.
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA;
authors.forename: Tisha B
authors.initials: TB
authors.lastname: Suboc
authors.affiliation: Graduate School of Biomedical Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, USA;
authors.forename: Daniel
authors.initials: D
authors.lastname: Knabel
authors.affiliation: Department of Kinesiology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, USA;
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Strath
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA;
authors.forename: Kodlipet
authors.initials: K
authors.lastname: Dharmashankar
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA;
authors.forename: Allison
authors.initials: A
authors.lastname: Coulliard
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA;
authors.forename: Mobin
authors.initials: M
authors.lastname: Malik
authors.affiliation: Department of Orthopaedic Surgery, University of Missouri-Kansas City, Kansas City, Missouri, USA;
authors.forename: Kristoph
authors.initials: K
authors.lastname: Haak
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA; Department of Pharmacology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. mwidlans@mcw.edu.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Widlansky
mesh_terms: D061725:Accelerometry; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001916:Brachial Artery / Q000503:physiopathology; D002318:Cardiovascular Diseases / Q000503:physiopathology* / Q000523:psychology; D004730:Endothelium, Vascular / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D057185:Sedentary Behavior; D014664:Vasodilation / Q000502:physiology*
keywords: blood pressure; endothelial function; exercise; hypertension; physical activity; sedentary time; steps; walking.