This chapter reflects upon the reality associated with running sports events in protected areas, in particular at the Peneda Gerês National Park (PNPG), with a particular focus on the Trans Peneda-Gerês (TPG), and understands its impacts within a sustainable tourism development perspective. With the diversity of landscapes and natural resources, and its characteristic villages, PNPG, as many other protected areas in Portugal, has a strong potential for Outdoor Sports/Tourism, offering some of Portugal's best running trails. As such, a considerable number of running events are currently being hosted. Based on a research process which includes both questionnaires and interviews, the authors propose to identify the profile and behavior of 2019 TPG edition's participants, and to assess local stakeholders' perception of economic, environmental, and social impacts, and to contribute to the discussion from a sustainable development perspective of the creation and management of tourism-related sports events, namely running, in protected areas.