Long term effects of self-determination theory and motivational interviewing in a web-based physical activity intervention: randomized controlled trial.
BACKGROUND
Our main objective in the current study was to evaluate the long-term effectiveness (12 months from baseline) of I Move (a web-based computer tailored physical activity intervention, based on self-determination theory and motivational interviewing). To this end, we compared I Move to a web-based computer tailored physical activity intervention based on traditional health behavior theories (Active Plus), and to a no-intervention control group. As a secondary objective, the present study aimed to identify participant characteristics that moderate the long term effects of I Move and Active Plus.


METHODS
A randomized controlled trial was conducted, comparing three research conditions: 1) the I Move condition, participants in this condition received I Move; 2) the Active Plus condition, participants in this condition received Active Plus; 3) the control condition; participants in this condition received no intervention and were placed on a waiting list. Main outcome measures were weekly minutes of moderate to vigorous physical activity and weekly days with minimal 30 min of physical activity. All measurements were taken by web-based questionnaires via the study website. Intervention effects were analyzed using multilevel linear regression analyses.


RESULTS
At 12 months from baseline, I Move was found to be effective in increasing weekly minutes of moderate to vigorous physical activity (ES = .13), while Active Plus was not. In contrast, Active Plus was found to be effective in increasing weekly days with ≥ 30 min PA at 12 months (ES = .11), while I Move was not. No moderators of the effects of I Move were found.


CONCLUSIONS
The results suggest that web-based computer tailored physical activity interventions might best include elements based on both self-determination theory/motivational interviewing and traditional health behavioral theories. To be more precise, it is arguable that the focus of the theoretical foundations, used in new web-based PA interventions should depend on the intended program outcome. In order to draw firm conclusions, however, more research on the effects of self-determination theory and motivational interviewing in web-based physical activity promotion is needed.


BACKGROUND
Dutch Trial Register NTR4129.
Open University of the Netherlands, Faculty of Psychology and Educational Sciences, P.O. box 2960, 6401, DL, Heerlen, The Netherlands. stijn.friederichs@ou.nl.
Stijn A H
SA
Friederichs
Department of Health Promotion, Maastricht University, P.O. Box 616, 6200, MD, Maastricht, The Netherlands. a.oenema@maastrichtuniversity.nl.
Anke
A
Oenema
Open University of the Netherlands, Faculty of Psychology and Educational Sciences, P.O. box 2960, 6401, DL, Heerlen, The Netherlands. catherine.bolman@ou.nl.
Catherine
C
Bolman
Open University of the Netherlands, Faculty of Psychology and Educational Sciences, P.O. box 2960, 6401, DL, Heerlen, The Netherlands. lilian.lechner@ou.nl.
Lilian
L
Lechner
D000328:Adult; D003201:Computers; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D009042:Motivation; D062405:Motivational Interviewing; D009043:Motor Activity; D017063:Outcome Assessment, Health Care; D026684:Personal Autonomy; D015397:Program Evaluation; D011582:Psychological Theory; D011795:Surveys and Questionnaires; D013995:Time; D016896:Treatment Outcome