title: Failure of post-action stages of the transtheoretical model to predict change in regular physical activity: a multiethnic cohort study.
abstract: BACKGROUND
  Predicting variation in meeting recommended levels of physical activity is important for public health evaluation.
  
  
  OBJECTIVE
  The purpose of this study is to determine the predictive value of stages of the Transtheoretical Model (TTM) for classifying people who meet the US Healthy People 2010 guideline for regular physical activity.
  
  
  METHODS
  A cohort (N = 497) from a random, multiethnic sample of 700 adults living in Hawaii was assessed at 6-month intervals three or more times for 2 years. Latent transition analysis was used to classify people according to TTM stages and separately according to whether they met the guideline. The predictive value of pre- vs. post-action stages was then tested.
  
  
  RESULTS
  Stages were more likely to falsely classify people as meeting the guideline than to falsely classify them as not meeting it. Probabilities of predicting 6-month transitions were about 50% for the stable class of meeting the guideline each time and just 25% for transitions between meeting and not meeting the guideline.
  
  
  CONCLUSIONS
  The TTM post-action stages had limited usefulness in this cohort. Further longitudinal study is needed to determine whether TTM stages can accurately classify transitions from physical inactivity to physical activity below recommended levels.
authors.affiliation: Department of Kinesiology, The University of Georgia, Ramsey Center, 330 River Road, Athens, GA 30602-6554, USA. rdishman@uga.edu
authors.forename: Rod K
authors.initials: RK
authors.lastname: Dishman
authors.forename: Nathaniel J
authors.initials: NJ
authors.lastname: Thom
authors.forename: Cherie R
authors.initials: CR
authors.lastname: Rooks
authors.forename: Robert W
authors.initials: RW
authors.lastname: Motl
authors.forename: Caroline
authors.initials: C
authors.lastname: Horwath
authors.forename: Claudio R
authors.initials: CR
authors.lastname: Nigg
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D005006:Ethnicity / Q000706:statistics & numerical data*; D005260:Female; D017408:Guidelines as Topic; D006306:Health Surveys; D040361:Healthy People Programs; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009043:Motor Activity; D011237:Predictive Value of Tests; D013997:Time Factors