The Effect of Playground- and Nature-based Playtime Interventions on Physical Activity and Self-esteem in UK School Children

School playtime provides opportunities for children to engage in physical activity (PA). Playground playtime interventions designed to increase PA have produced differing results. However, nature can also promote PA, through the provision of large open spaces for activity. The purpose of this study is to determine which playtime interventions are most effective at increasing moderate-to-vigorous physical activity (MVPA) and if this varies by school location. Fifty-two children from an urban and rural school participated in a playground sports (PS) and nature-based orienteering intervention during playtime for one week. MVPA was assessed the day before and on the final day of the interventions using accelerometers. Intervention type (p < 0.05) and school location (p < 0.001) significantly influenced MVPA; with PS increasing MVPA more than nature-based orienteering. Urban children seemed to respond to the interventions more positively; however, differences in baseline MVPA might influence these changes. There was a positive correlation for fitness and MVPA during PS (r = 0.32; p < 0.05), but not nature-based orienteering (p > 0.05). The provision of PS influences PA the most; however, a variety of interventions are required to engage less fit children in PA.