The heterogeneity in reported effects was reduced in higher quality studies , when physical activity was self-directed with some professional guidance and when there was on-going professional support .
Our review suggests that physical activity interventions have a moderate effect on self reported physical activity and cardio-respiratory fitness , but not on achieving a predetermined level of physical activity .
Due to the clinical and statistical heterogeneity of the studies , only limited conclusions can be drawn about the effectiveness of individual components of the interventions .
BACKGROUND Little is known about the effectiveness of strategies to enable people to achieve an increase in their physical activity .
OBJECTIVES To assess the effects of interventions for promoting physical activity in adults aged 16 years and older , not living in an institution .
Evaluation of the results of a randomized controlled trial: how to define changes between baseline and follow-up.
OBJECTIVE The most common way to evaluate the effect of an intervention is to compare the  intervention and nonintervention groups regarding the change in the outcome variable between baseline and follow-up ; however , there are many different ways to define " changes . " The purpose of this article is to demonstrate how different definitions of " change " used in the analysis can influence the results of a study . STUDY DESIGN AND SETTING Two different r and omized controlled trials were used as examples . RESULTS The results of the analyses showed that for continuous outcome variables , analysis of covariance seems to be the most appropriate because it corrects for the phenomenon of regression to the mean . For dichotomous outcome variables , multinomial logistic regression analysis with all possible changes over time as outcome seems to be the most appropriate , especially because of its straightforward interpretation . CONCLUSION A different definition of " change " can lead to different results in the evaluation of the effect of an intervention
The heterogeneity in reported effects was reduced in higher quality studies , when physical activity was self-directed with some professional guidance and when there was on-going professional support .
Our review suggests that physical activity interventions have a moderate effect on self reported physical activity and cardio-respiratory fitness , but not on achieving a predetermined level of physical activity .
Due to the clinical and statistical heterogeneity of the studies , only limited conclusions can be drawn about the effectiveness of individual components of the interventions .
BACKGROUND Little is known about the effectiveness of strategies to enable people to achieve an increase in their physical activity .
OBJECTIVES To assess the effects of interventions for promoting physical activity in adults aged 16 years and older , not living in an institution .