||Natural & Protected Areas (N&PA) have always promoted visitation and leisure uses of its terri-tories, but these have changed dramatically over the last few decades. Soft and contemplative activities like walking, hiking, or camping have moved to hard skill/adventure practices such as trail running (TR), mountain biking (MTB), among others carrying new challenges to these territo-ries. The urbanization/globalization of the world population have for sure played some role in these new practices, where N&PA are used at the same time as an escape from modern ways of life reconnecting people to the environment/wild, but also attracting urban lifestyles, usually fore-seen as new opportunities for local and regional development making balance between positive and negative impacts difficult to measure and monitor. Large nature-based sports events of MTB and more recently of TR are two of these new uses that can gather up to thousands of practi-tioners and visitors over several days depending on different factors. Although “natural/rural” landscapes and positive climbs are not exclusive of N&PA its not uncommon that these concen-trate the most appellative territories for these nature-based activities. Previous studies on MTB have found that these events tend to happen in Portugal more close to N&PA (Nogueira Mendes, Farías-Torbidoni & Pereira da Silva, 2021) and that within Lisbon Metropolitan Area, 60% of MTB rides target at least one of its peri-urban N&PA – that altogether occupy only 10% of the territory (Nogueira Mendes, Farías-Torbidoni & Pereira da Silva [submitted]). Julião, Valente & Nogueira Mendes (2018) found that 30% of the actual trail runners are old mountain bikers, sug-gesting that MTB is being gradually replaced by TR in terms of popularity. What could be a pressure relief in terms of environmental and social im-pacts from MTB, could be a new wave of concerns to N&PA managers, since TR is bringing not just older but also new users and different demands.To better understand the role of N&PA on MTB and TR events organized in Portugal, the location of all these nature-based sports events promoted in 2018 was plotted against the Na-tional Network of Classified Areas (SNAC), to eval-uate its attractiveness and possible susceptibility. SNAC includes the National Network of Protected Areas (RNAP), Natura 2000 Network sites, Ramsar sites, and UNESCO Biosphere Reserves, covering a total of 29,58% of the country area that follows under the jurisdiction of the National Institute of Nature Conservation and Forestry in terms of recreational and sports use. Although both MTB and TR are sports activities, many events fall off the jurisdiction of its sports federations and their official calendars, requiring secondary data to monitor it at the national level. Data was gath-ered from Timing companies – often hired to manage registrations and insurances, along with national & regional federations/associations, so-cial media, municipalities, and local cultural and sports clubs webpages. Extra searches were con-ducted within the WWW during February 2019 using the terms: “MTB”, “TR” and “2018”. Results have found 608 MTB and 461 TR events scattered all over Portugal mainland, that were georefer-enced and uploaded to a GIS project (Figure 1). Proximity to all protected and classified areas was measure using a 10 km search radius since most MTB and TR events have several race lengths.