title: Lifestyle intervention effects on the frequency and duration of daily moderate-vigorous physical activity and leisure screen time.
abstract: How a healthy lifestyle intervention changes the frequency and duration of daily moderate-vigorous physical activity and sedentary behavior has not been well characterized. Secondary analyses of data from the Make Better Choices randomized controlled trial were conducted to evaluate how interventions to increase physical activity or reduce leisure screen time affected the frequency and duration of these behaviors during treatment initiation and follow-up.
  
  
  
  Participants were 202 adults who exhibited insufficient physical activity, excessive screen time and poor diet during a 14-day baseline screening period. The design was a randomized controlled trial with a 3-week intervention period followed by eight 3- to 7-day bursts of data collection over the 6-month follow-up period after intervention termination. Participants self-reported on their physical activity and screen time at the end of each day.
  
  
  
  A 2-part multilevel model indicated that, relative to baseline levels, the physical activity intervention increased the odds of daily moderate-vigorous intensity physical activity (frequency) but not the duration of activity during the intervention period and these effects persisted (albeit somewhat more weakly) during the follow-up period. The screen time intervention reduced both the frequency and duration of daily screen time from the beginning of the intervention through the follow-up period.
  
  
  
  A 3-week intervention increased daily physical activity frequency but not duration, and reduced both the frequency and duration of daily leisure screen time. These effects were maintained over 20 weeks following the end of the intervention. (PsycINFO Database Record
authors.affiliation: Department of Kinesiology.
authors.forename: David E
authors.initials: DE
authors.lastname: Conroy
authors.affiliation: Department of Public Health Sciences, University of Chicago.
authors.forename: Donald
authors.initials: D
authors.lastname: Hedeker
authors.affiliation: Department of Preventive Medicine, Northwestern University.
authors.forename: H G
authors.initials: HG
authors.lastname: McFadden
authors.affiliation: Department of Preventive Medicine, Northwestern University.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Pellegrini
authors.affiliation: Department of Preventive Medicine, Northwestern University.
authors.forename: Angela F
authors.initials: AF
authors.lastname: Pfammatter
authors.affiliation: Department of Preventive Medicine, Northwestern University.
authors.forename: Siobhan M
authors.initials: SM
authors.lastname: Phillips
authors.affiliation: Department of Preventive Medicine, Northwestern University.
authors.forename: Juned
authors.initials: J
authors.lastname: Siddique
authors.affiliation: Department of Preventive Medicine, Northwestern University.
authors.forename: Bonnie
authors.identifier: 0000-0003-0692-9868
authors.initials: B
authors.lastname: Spring
mesh_terms: D000328:Adult; D002755:Choice Behavior; D003201:Computers / Q000706:statistics & numerical data*; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006801:Humans; D007899:Leisure Activities; D008297:Male; D008875:Middle Aged; D057185:Sedentary Behavior; D057566:Self Report; D013690:Television / Q000706:statistics & numerical data*; D055815:Young Adult