An online physical activity program for German and Dutch adults delivered by SMS.

The main aim of this study is to assess the effectiveness of a physical exercise intervention delivered to German and Dutch adults via mobile telephone short messages service (SMS). Secondly, it will be investigated whether and how an exercise intervention may affect other health behaviors.



Using a randomized controlled trial, levels of exercise, social cognitions, and other health behaviors will be assessed at four measurement points among 260 adults. The experimental group will receive several mobile phone short messages tailored to exercise-specific cognitions from the HAPA and I-Change model.



By means of multivariate analyses, we expect to find the experimental group being more physically active and having a healthier lifestyle in general compared to the control group.

Tailored feedback delivered via SMS may be an effective way to improve exercise.



Exercise interventions may affect other health behaviors.



We expect to find the experimental group being more physically active and having a healthier lifestyle in general compared to the control group.

Levels of physical exercise, social cognitions (self-efficacy, intention, action plans), and other health behaviors (nutrition, alcohol intake, smoking) will be assessed at up to four measurement points:

T0 (baseline);

T1 (after one week);

T2 (after two weeks);

T3 (after three weeks).



Demographic variables (gender, age, marital status, educational level, height and weight) will be measured at T0. Height and weight will also be measured at T3.

Since eHealth interventions hold promise for increasing reach of people and health behavior change, a bilingual (German and Dutch), web-based tailored program for adults of the general population will be developed aimed at physical activity.



By use of questionnaires, physical activity level, nutrition, alcohol intake and smoking behavior will be assessed, in addition to multiple health behavior cognitions (e.g., transfer) and demographic factors.



Using an RCT, our respondents will be randomized among two groups: The control group will receive the questionnaire four times (at baseline and afterwards once per week plus 1 general short message) whereas the experimental group will, additionally, receive tailored short messages on their mobile phones concerning physical activity. The messages will be based on different social-cognitive exercise-specific factors, such as self-efficacy, planning and motivation.



Data for the analyses will come from the two subsamples – one in Germany and one in the Netherlands.