(1) A study on cross-cultural adaptation and validation of internationally used questionaires (the International Physical Activity Questionnaire (IPAQ-SF), the Physical Activity Neighborhood Environment Scale (PANES) and the Neighborhood Environemnt Walkability Scale (NEWS) in Nigeria; (2) A population based cross-sectional study to determine the associations between outcomes (physical activity, and overweight status), and environmental variables and socioeconomic status among adults in Nigeria; (3) A study on investigation of physical activity as potential mediator of associations of environmental variables with overweight; (4) A comparative study on physical activity and sedentary behaviour patterns between Nigerian and Belgian adults; (5) A study on differences in associations between environmental variables and physical activity, and overweight between Nigerian and Belgian adults.