title: Predicting behavioral intentions and physical exercise: a test of the health action process approach at the intrapersonal level.
abstract: OBJECTIVE
  Theories of health behavior are usually tested on the between-person level. Associations between variables on the between- and the within-person level, however, can differ substantially. Thus, in order to better understand intrapersonal processes in the domain of health behavior, studies applying within-person analyses are needed. This study tested the Health Action Process Approach (HAPA) on the within- and between-person level in the context of physical exercise.
  
  
  METHODS
  Participants were 265 first-year students who completed nine online questionnaires every second week. Data were analyzed by focusing on intrapersonal associations applying multilevel modeling.
  
  
  METHODS
  Intentions for physical exercise and self-reported physical exercise served as main outcome measures.
  
  
  RESULTS
  Analyses mainly confirm associations specified by the HAPA at the intrapersonal level: outcome expectancies and self-efficacy, but not risk awareness, were positively associated with intentions for physical exercise. Physical exercise in turn was positively associated with intentions, self-efficacy, action control, but not with action planning.
  
  
  CONCLUSIONS
  The HAPA could be confirmed on the within-person level. Future studies should focus on testing other theories of health behavior at the within-person level.
authors.affiliation: Department of Psychology, University of Zurich, Switzerland. urte.scholz@psychologie.uzh.ch
authors.forename: Urte
authors.initials: U
authors.lastname: Scholz
authors.forename: Roger
authors.initials: R
authors.lastname: Keller
authors.forename: Sonja
authors.initials: S
authors.lastname: Perren
mesh_terms: D000293:Adolescent; D000328:Adult; D015444:Exercise; D005260:Female; D005544:Forecasting; D015438:Health Behavior; D006801:Humans; D033182:Intention; D008297:Male; D008875:Middle Aged; D011795:Surveys and Questionnaires; D013557:Switzerland; D055815:Young Adult