Effect of a web-based intervention to promote physical activity and improve health among physically inactive adults: A population-based randomized controlled trial

Background: many people in western countries do not follow public health physical activity (pa) recommendations. web-based interventions provide cost- and time-efficient means of delivering individually targeted lifestyle modification at a population level. objective: to examine whether access to a website with individually tailored feedback and suggestions on how to increase pa led to improved pa,anthropometrics,and health measurements. methods: physically inactive adults (n = 12,287) participating in a nationwide ehealth survey and health examination in denmark were randomly assigned to either an intervention (website) (n = 6055) or a no-intervention control group (n = 6232) in 2008. the intervention website was founded on the theories of stages of change and of planned behavior and,apart from a forum page where a physiotherapist answered questions about pa and training,was fully automated. after 3 and again after 6 months we emailed participants invitations to answer a web-based follow-up questionnaire,which included the long version of the international physical activity questionnaire. a subgroup of participants (n = 1190) were invited to a follow-up health examination at 3 months. results: less than 22.0% (694/3156) of the participants logged on to the website once and only 7.0% (222/3159) logged on frequently. we found no difference in pa level between the website and control groups at 3- and 6-month follow-ups. by dividing participants into three groups according to use of the intervention website,we found a significant difference in total and leisure-time pa in the website group. the follow-up health examination showed no significant reductions in body mass index,waist circumference,body fat percentage,and blood pressure,or improvements in arm strength and aerobic fitness in the website group. conclusions: based on our findings,we suggest that active users of a web-based pa intervention can improve their level of pa. however,for unmotivated users,single-tailored feedback may be too brief. future research should focus on developing more sophisticated interventions with the potential to reach both motivated and unmotivated sedentary individuals. trial registration: clinicaltrials.gov nct01295203; http://clinicaltrials.gov/ct2/show/nct01295203 (archived by webcite at http://www.webcitation.org/6b7hdmqiq).