title: Relative importance of step count, intensity, and duration on physical activity's impact on vascular structure and function in previously sedentary older adults.
abstract: BACKGROUND
  Age-related endothelial dysfunction and vascular stiffening are associated with increased cardiovascular (CV) risk. Many groups have encouraged goals of ≥10 000 steps/day or ≥30 min/day of moderate intensity physical activity (MPA) to reduce age-related CV risk. The impact of MPA on the vasculature of older adults remains unclear.
  
  
  RESULTS
  We randomized 114 sedentary older adults ages ≥50 to 12 weeks of either no intervention (group 1), a pedometer-only intervention (group 2), or a pedometer with an interactive website employing strategies to increase the adoption of habitual physical activity (PA, group 3). Endothelial function by brachial flow-mediated dilation (FMD%), vascular stiffness by tonometry, step-count by pedometer, and PA intensity/distribution by accelerometer were measured. Step-count increased in groups 2 (5136±1554 to 9596±3907, P<0.001) and 3 (5474±1512 to 8167±3111, P<0.001) but not in group 1 (4931±1667 to 5410±2410). Both groups 2 and 3 increased MPA ≥30 min/day. Only group 3 increased MPA in continuous bouts of ≥10 minutes (P<0.001) and improved FMD% (P=0.001). Neither achievement of ≥10 000 steps/day nor ≥30 min/day of MPA resulted in improved FMD%. However, achieving ≥20 min/day in MPA bouts resulted in improved FMD%. No changes in vascular stiffness were observed.
  
  
  CONCLUSIONS
  MPA reverses age-related endothelial dysfunction, but may require MPA to be performed in bouts of ≥10 minutes duration for ≥20 min/day to be effective. Commonly encouraged PA goals do not guarantee improved endothelial function and may not be as effective in reducing CV risk.
  
  
  BACKGROUND
  Clinicaltrials.gov. UNIQUE IDENTIFIER: NCT-01212978.
authors.affiliation: Division of Cardiovascular Medicine, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Tisha B
authors.initials: TB
authors.lastname: Suboc
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Strath
authors.forename: Kodlipet
authors.initials: K
authors.lastname: Dharmashankar
authors.forename: Allison
authors.initials: A
authors.lastname: Coulliard
authors.forename: Nora
authors.initials: N
authors.lastname: Miller
authors.forename: Jingli
authors.initials: J
authors.lastname: Wang
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Tanner
authors.forename: Michael E
authors.initials: ME
authors.lastname: Widlansky
mesh_terms: D056044:Actigraphy; D000367:Age Factors; D000368:Aged; D000375:Aging; D001916:Brachial Artery / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005260:Female; D015438:Health Behavior; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged; D009043:Motor Activity; D020127:Recovery of Function; D012307:Risk Factors; D040242:Risk Reduction Behavior; D057185:Sedentary Behavior; D013997:Time Factors; D014652:Vascular Diseases / Q000175:diagnosis / Q000503:physiopathology / Q000517:prevention & control*; D059289:Vascular Stiffness; D014664:Vasodilation; D014922:Wisconsin
keywords: elderly; endothelial function; physical exercise