Recreational trail runners often participate in online community forums where they can freely read posted messages, join discussions and/or introduce new discussion topics. This tool can enhance learning as runners connect with other trail runners and reflect on how they can better organize their own practice. Studying forum activity would provide greater insight into the relationship between field practice and dedicated forums. The aim of this study was therefore to detect the topics discussed online by trail runners in order to understand how they collectively look for solutions that help them adapt to issues that emerge during actual practice. The discussion topics (n = 171) on the forum hosted by the Raidlight brand were examined using inductive content analysis, which distinguished two general dimensions. The first dimension was training and had four first-order themes (i.e., "specific trail running sessions", "complementary trail running sessions". "training plans" and "specific questions about races") grouped into two second-order themes (i.e., "training session contents" and "structure and schedule"). The second dimension was health and had seven first-order themes (i.e., "tendinitis", "muscle issues", "foot issues", "sprains and fractures", "pain", "physiology" and "substances and practitioners") grouped into two second-order themes (i.e., "pain and injury" and "prevention"). The results indicate that the issues that trail runners discuss on forums are significant and that the successions of questions and solutions are a fruitful means for building, enriching and adjusting their activity as they cope with constraints. As a practical consequence, suggestions for improving such online platforms are made.