# Prediction of Injuries in CrossFit Training: A Machine Learning Perspective
## 4 Discussion  
In the present study six risk factors for injury during CF training were identified: (i) CF participation in months/years (CF experience); (ii) days/weeks of training; (iii) training duration; (iv) prior to CF level of activity; (v) medical history/previous injuries; (vi) gender. These risk factors have been reported in previous studies related to CF injuries either individually or combined with other risk factors using various statistical methods. [PERSON] et al. (2017) [15] identified CF participation (CF experience) as a risk factor of injury. They suggested that coaches and athletes should focus on correct movement patterns and workouts designed for beginners. This is something that happens in most CF boxes. Every CF training center has a different beginners' program; therefore, the quality of coaching might vary [15]. It is reasonable that loads can be managed better by more experienced athletes and thus they have smaller injury risk than inexperienced ones [50]. [PERSON] et al. (2020) [21] found that a 1-year increase in CF experience reduced the odds of sustaining a musculoskeletal injury related to CF by approximately half. On the other hand, [PERSON] et al. (2018) [18] reported that CF athletes with 3 years of experience reported more injuries (43.1%) compared with those with 1 to 3 years (38.8%) and those with less than 1 year (18.0%) of experience. In agreement with their findings [PERSON] et al. (2017) [9] and [PERSON] et al. (2019) [19] found that more CF experience (in years) was associated with higher odds of sustaining a musculoskeletal injury related to CF. Training frequency is also an important risk factor for injury in CF. According to the American College of Sports Medicine (ACSM) [51] in order to obtain the physiological training effects, such as the cardiovascular conditioning improvement and muscle hypertrophy, training program prescription should include at least 3 training sessions per week. [PERSON] & [PERSON] (2019) [7] in a sample of 885 worldwide athletes, found that participants of CF who trained twice or less than a week had a 3.24 greater probability of injury than those who exercised more. [PERSON] et al. (2018) [18] and [PERSON] and [PERSON] (2019) [7] were in agreement with the finding of the aforementioned studies and particularly they stated that practitioners who trained fewer times a week had increased probability to have an injury than those who trained three or more times a week. There is conflicting evidence whether the duration of CF participation is a risk factor for injury. [PERSON] et al. (2020) [6] found a positive correlation between injury prevalence and training duration per week in CF athletes. This comes in agreement with studies of [PERSON] et al. (2017) [9] and [PERSON] et al. (2016) [11] who concluded that a higher length of participation in CF was associated with a higher injury incidence. On the other hand [PERSON] (2017) [16], [PERSON] et al. (2016) [11] and [PERSON] et al. (2014) [8] found no significant difference between injury incidence and training session duration. Further research is needed to determine if CF training duration is related to injuries in CF. The present study showed that referring medical history to the coach is a risk factor for future injuries in CF. Medical history knowledge can prevent injuries by modifying CF exercises' parameters and informing coach of any health problems that may affect performance or problems that may endanger the trainee's health. Therefore, supervision by a proper and trained coach is considered of paramount importance. There is strong evidence that previous injuries increase the risk of future injuries in several sports [52; 53; 54; 55] as well as in CF [21]. To our knowledge there is no clear evidence regarding gender and its relationship with CF related injuries. It is difficult to make a conclusive statement on this since some studies have statistical significant results [8; 10; 56] but others did not [9; 11].