## 4 Discussion
### Main Findings
Besides, shops in the Netherlands (except for grocery stores) close at approximately the same time a working day ends, which also hinders adults in visiting those locations on weekdays. Green spaces can be important facilitators of PA behavior [44], but varying types of green spaces can contribute to MVPA of diverse subpopulations in different ways. For example, this study found that MVPA levels in small green area were lower for car owners than for adults who do not own a car. On the other hand, levels of MVPA in larger green area were higher for car owners than for adults who do not own a car. This may be explained by previous studies that showed that car owners tend to undertake more PA outside their residential neighborhood [25]. As small green areas (_i.e._, parks and allotments) are likely to be present within one's residential neighborhood, and larger green area (_i.e._, forests, recreational areas, moorland) are often located further from the home, it is plausible that car owners use their cars to visit larger green areas and be physically active there, whereas adults without a car visit small green areas within their neighborhood, which they can reach by foot or bike. Not having a car may thus be a constraint for adults to engage in MVPA in larger green areas, but also in other places. Interestingly, living in the neighborhoods Zuid-Oost and West (Maastricht) was negatively correlated to MVPA in larger green areas, whereas these neighborhoods have the highest amounts of larger green areas as compared to the neighborhoods of Rotterdam. As we found that car owners spent more time in larger green areas, proximity of and travel distance to larger green spaces may thus become of less importance. MVPA at sports facilities was lowest for adults living in Oude Noorden (Rotterdam). They also spent least time in sports facilities, compared to participants of the other three neighborhoods. This may be influenced by the presence of sports facilities in one's neighborhood, as the amount of sports facilities within the neighborhood Oude Noorden are lower than in Kralingen-West, Zuid-oost and West. Visual analyses of data on MVPA behavior at sports facilities indicated that adults may have taken off the devices during exercise, as we identified gaps in time. Since data before and after such time gaps indicated that participants were at a sports facility, it seems plausible that during the gap, participants were also at that facility. Results may thus underestimate MVPA levels at sports facilities. Other residential areas were positively correlated to MVPA behavior of dog owners. This finding is not unexpected, as dog owners are likely to walk their dog in residential areas such as the residential neighborhood or adjacent neighborhoods. Adults of older age and adults with a poorer health status spent less time in MVPA in other residential areas. An explanation for this may be that these adults experience physical limitations (e.g., difficulties with walking) that hinder them to be physically active in these areas. In addition, employed adults spent less time in MVPA in other residential areas, which may be explained by the obligation to spend a certain amount of time at the workplace. We found that transport-related MVPA differs between native Dutch adults, and western and non-western immigrants. This is supported by figures on cycling in the Netherlands, which show that native Dutch adults cycle more often than individuals with other ethnic origins [48]. Additional analyses revealed that compared to autochthonous adults, significantly less non-western immigrants have a bicycle. Here, cultural differences seem to influence MVPA behavior. Physical limitations seem to be of influence as well, as we found that adults who reported lower levels of health status had lower levels of transport-related MVPA. It may be that adults who reported a very good health status had less difficulties with walking and cycling than adults with a lower health status, for example, because they felt better, or had less health complaints.