Trail running is characterised by running on off-road surfaces, in natural environments, and often involves large elevation changes. The consequences of injury in trail running are of concern as medical support in remote regions are challenging. This highlights the importance of identifying trail runners at increased risk for injury before trail running participation in remote regions. It is also important to identify increased injury risk in trail runners not participating in remote regions to design individualised injury risk management strategies. At the start of this research project, limited research evidence was available on injury in trail running. To determine the epidemiology and clinical characteristics of injury in trail running, a systematic review was conducted (Chapter 2). A wide injury incidence range of 1.6–61.2 injuries per 1000 h of running were reported. The most injured anatomical region reported was the lower limb, mostly affecting the foot. The review highlighted the limited research evidence on injury in shorter distance trail running. In Chapter 3, the epidemiology, clinical characteristics, and associated injury risk factors were investigated prospectively. An overall injury rate of 19.6 running-related injuries (RRIs) per 1000 h and an RRI mean prevalence of 12.3% were reported. The most injured anatomical site was the lower limb (82.9%), affecting the knee (29.8%). Independent risk factors for RRIs among were a history of previous RRI in the past 12 months (p=0.0032) and having a chronic disease (p=0.0188). In Chapter 4, the epidemiology, clinical characteristics, and associated injury risk factors were investigated specifically in shorter distance trail runners through analysing an existing dataset. The retrospective annual incidence for gradual onset running-related injuries (GORRIs) was 13%. The most injured anatomical region was the lower limb (94%) with soft tissue injuries accounting for most (83%) GORRIs. Longer race distance (p