title: The Impact of Moderate Intensity Physical Activity on Cardiac Structure and Performance in Older Sedentary Adults.
abstract: BACKGROUND
  Sedentary aging leads to adverse changes in vascular function and cardiac performance. We published improvements in vascular function with moderate intensity physical activity (PA) in continuous bouts. Whether moderate intensity PA also impacts cardiac structure and cardiovascular performance of the aging left ventricle (LV) is unknown.
  
  
  METHODS
  We recruited and analyzed results from 102 sedentary older adults ages ≥ 50 from a randomized controlled trial with 3 study groups: control (group 1), a pedometer-only intervention (group 2), or a pedometer with an interactive website employing strategies to increase habitual physical activity (PA, group 3) for 12 weeks. Transthoracic echocardiograms were performed prior to and following the 12 week intervention period to assess cardiac morphology, left ventricular (LV) systolic performance, LV diastolic function, arterial and LV ventricular elastance. Step count and PA intensity/distribution were measured by pedometer and accelerometer.
  
  
  RESULTS
  We found no significant changes in cardiac morphology. Further, we found no improvement in the aforementioned cardiac functional parameters. Comparing those who achieved the following benchmarks to those who did not showed no significant changes in cardiac structure or performance: 1)10,000 steps/day, 2) ≥ 30 minutes/day of moderate intensity physical activity, or 3) moderate intensity PA in bouts ≥ 10 minutes for ≥ 20 minutes/day.
  
  
  CONCLUSIONS
  In sedentary older adults, increasing moderate intensity PA to currently recommend levels does not result in favorable changes in LV morphology or performance over 12 weeks. More prolonged exposure, higher PA intensity, or earlier initiation of PA may be necessary to see benefits.
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Tisha B
authors.initials: TB
authors.lastname: Suboc
authors.affiliation: Department of Kinesiology, University of Wisconsin-Milwaukee ; Center for Aging and Translational Research, University of Wisconsin-Milwaukee, Milwaukee, WI.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Strath
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Kodlipet
authors.initials: K
authors.lastname: Dharmashankar
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Leanne
authors.initials: L
authors.lastname: Harmann
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Allison
authors.initials: A
authors.lastname: Couillard
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Mobin
authors.initials: M
authors.lastname: Malik
authors.affiliation: Graduate School of Biomedical Sciences, Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Kristoph
authors.initials: K
authors.lastname: Haak
authors.affiliation: Graduate School of Biomedical Sciences, Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Daniel
authors.initials: D
authors.lastname: Knabel
authors.affiliation: Department of Medicine, Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, WI ; Department of Pharmacology, Medical College of Wisconsin, Milwaukee, WI.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Widlansky
keywords: Aging; Cardiac Function; Echocardiography; Physical Activity; Sedentary