# Injury Incidence and Pattern in Elite Young Male and Female Trail Runners
## 4 Discussion
Furthermore, it is suggested that the injury risk in runners is lower at ages between 18 and 30 years [42], so runners younger than 18 years may maintain or reduce this lower risk. According to our study, most of the injuries (92%) were in the lower body, which is in line with the current literature [43]. The body regions that registered the most occurrences were the ankles (49.5%), the knees (17.9%), the lower legs (9.5%), and the thighs (5.3%). These data differ from other studies such as [PERSON] et al. [38], who concluded that most of the injuries in trail running occurred in the knees (26.5%), ankles (21.6%), and feet (16.7%). This discrepancy might be due to the age and type of runners, as well as the distances studied, where the paces are lower and there is a tendency to risk less. In other studies with runners [36; 44; 45], most occurrences vary between knees, hamstrings, shins (tibialis), and the hip, but they are based on injuries suffered in different types of runners and modalities, being the sprint modalities the ones that report the most [46]. These studies were related to athletics modalities, where the terrain is quite stable, which affects the body region of occurrence. Another source of dissimilarity is that the race distance, short-, middle- or long-distance, influences the time of execution, the previous warm-up, or the stride length. Therefore, the data of these studies from races characterized by constant and maintained stride with equal impacts may not be entirely comparable with those obtained in the present study. It is generally accepted that the main body area of injury in mountaineering is the ankle with 40%, followed by the knee (10.7%), the foot (7.9%), and the lower leg (7.4%) [47], which are in line with our results. Thus, the continuous variability of the terrain, together with the unevenness, favors the incidence of this type of injury over others more typical of repetitive cyclic movements in much more stable terrain. The same review study reported orienteering injuries, where the most affected area is the ankle (29.8%), followed by the knee (18.1%) and lower leg (14.8%), percentages values in line with [PERSON] [40], who observed that injuries in orienteers were located in the ankle, lower leg (both 27.27%) and knee (25.77%). This would confirm that the terrain is of key importance in terms of the areas affected by injury, rather than the running movement. Although the majority were directly related injuries and occurred more during training (40.0%) versus in competition (33.7%), if the time spent in both groups is considered, the percentage of injuries in competition is much higher than while training, indirect injuries, or not at all related with trail running. This has been widely reported in several studies produced during practice and competition in different sports [48; 49; 50; 51], which concluded that the percentage of injury per 1000 h of competition is higher than that of injuries produced during training/warm-up. These same studies also suggested that this increase might be caused by a rise in intensity. The review on ultra-endurance runners conducted by [PERSON] and [PERSON] [28] also suggested that the body region, diagnosis, and rate of injuries differed between competition and training as well as between different ultra-endurance races. While the back, knee, and bone stress injuries are common during training, in short ultra-trail races (65 km), the incidence is higher and it mainly affects the foot (plantar fascitits), ankle (ankle sprain), and knee. They also concluded that the main injured regions are the knee (patella femoral pain syndrome), and ankle in long continuous races. So, for the particular case of trail running, another reason can be greater exposure to risk when trying to maintain high intensities in unstable and varied terrain. In line with the above, our study showed that most of the injuries are due to acute sudden onset (49.5%), repetitive sudden onset (34.7%), and repetitive gradual onset (15.8%).