DISCUSSION
This study characterized the injury profile in a training center for soccer athletes from a club of the first Brazilian division. It was observed that the incidence of injuries was 50% for the Sub15 team, 47.61% for the Sub 17 team, and 39.53% for the Sub 20 team. Although no correlation was found between the injury index and anthropometric factors and with the position of the athletes, specific training characteristics in each category, as well as preventive and regenerative programs and financial interests can explain the difference in the incidence of injury and time off in each category.
The incidence of injuries observed during games 13 (21%) was lower than those that occurred in training 49 (79%). However, when we analyze the ratio of injuries that occurred every thousand hours of training and playing, we have higher values ​​of injuries that occurred in games; 25.98 and 42.27 respectively. These data coincide with those of a study carried out in a professional club of the first division of Brazilian football, which shows an 18 times higher rate of injuries in games [5]. Other studies have reported lower values: an average of 27.5 / 1000 hours by the Union of European Football Associations (UEFA) [14] and 21.8 / 1000 hours by teams from the Japanese first division [15]. This fact can be explained by the high number of matches played in Brazilian football when compared to other countries.
In the present study, the mean BMI value was 22.8 and there was no correlation between this variable and the number of injuries, different from what was shown in the study by Rodrigues et al. [18], where a higher injury rate was found in the group of athletes with a BMI of 18.5 to 24.9 and in the group of athletes with a BMI <18, a lower number of injuries was found, and this study was conducted in basic categories. There were no athletes with a BMI <18 to observe the number of injuries in this BMI range.
In this study, the anatomical region most affected was the lower limbs, where a number of 18 injuries were found in the thigh, 12 injuries in the ankle, 12 injuries in the knee, 7 injuries in the groin, and one injury in the calf. A smaller number of injuries were found in the upper limbs, with 2 being documented on the shoulder, 4 on the hand, and 2 on the elbow. These results are related to those of Rodrigues et al. [18] where similar data were found in baseline categories: 18 ankle injuries, followed by 14 knee injuries, 13 hip/thigh injuries, and 5 wrist, hand, and fingers injuries. However, these findings do not agree with a study carried out in a professional club, where only lower limb injuries were found. Most of the injuries found in this study were non-contact and non-recurring. The recurrence rate (21%) is within what is reported in the literature (20-25%) [18]. Other authors have found even lower recurrence values ​​in professional elite football [5].
Regarding the severity of the injuries, no correlation was found with age, BMI, position, recurrence, and time when the injury occurred. This can be explained by the fact that the sample is homogeneous with respect to BMI. In addition, although the athletes have a defined position in their respective teams, most of the activities performed in training situations are similar for all positions. Although no correlation was found between severity and the time when the injuries occurred, all knee sprains that resulted in rupture of the anterior cruciate ligament occurred during official matches.
In this context, a systematic review and meta-analysis of epidemiological data on injuries in professional male soccer were carried out. The overall incidence of injuries in professional male soccer players was 8.1 injuries/1000 hours of exposure. The incidence of gambling injuries (36 injuries/1000 hours of exposure) was almost 10 times higher than the incidence rate of training injuries (3.7 injuries/1000 hours of exposure). Lower extremity injuries had the highest incidence rates (6.8 injuries / 1000 hours of exposure). The most common types of injury were muscle/tendon (4.6 injuries/1000 hours of exposure), often associated with traumatic incidents. Mild injuries (1-3 days wasted) were the most common. The injury incidence rate in the top 5 European professional leagues was not different from the professional leagues in other countries (6.8 vs 7.6 injuries/1000 hours of exposure, respectively) [19].