Incidence of Injuries in French Professional Soccer Players

965 Incidence of Injuries in French Professional Soccer Players Authors M. Dauty, S. Collon Affiliations Médecine Physique et Réadaptation, CHU Nantes, France Orthopedic, CHU Nantes, France Key words soccer injury epidemiology Abstract In this prevalence cohort study, injuries sustained during 5 seasons in a professional soccer team were investigated according to the different soccer seasons, number of matches per season, month the injury occurred, location, severity, playing position and the team s rank at the end of the French professional championship. Altogether, 9 injuries in 7 professional soccer players were reported. Injury per h of exposure during matches and training was 4.7 ± 5. This did not vary significantly between seasons. However, injury increased after the year and constantly exceeded 4.. In the same way, after muscle injury always exceeded per h of exposure. Injury peaked during the month of January. Hamstring muscle injury represented the most frequent injury. No difference in injury was found according to the playing position or to the season whether the team participated or not in the European cup. No correlation was found with the team s rank at the end of the French championship. This study highlighted no significant variation on injury over a 5-season period except for the muscle injury rate in high level soccer players. accepted after revision June 9, Bibliography DOI http://dx.doi.org/.55/s--888 Published online: November, Int J Sports Med ; : 965 969 Georg Thieme Verlag KG Stuttgart New York ISSN 7-46 Correspondence Dr. Marc Dauty Médecine Physique et Réadaptation CHU Nantes Hôpital Saint Jacques 445 Nantes France Tel.: +//484 6 Fax: +//484 69 marc.dauty@chu-nantes.fr Introduction According to different studies, the of injury during soccer match-play is 5 times superior to the of injury during training [9,, 4, 6, 7, ]. When training and matches are grouped, the injury ranges from.9 to. and reflects the consequences of all the injuries that occurred during the season and their physical impact on professional soccer players [, 8, 5, ]. However, investigations have tended to examine injury across or seasons [,, 6, 7, ]. To our knowledge, data on injury rates collected and compared over multiple seasons are scarce and further research on inter-seasonal variations in injury is therefore warranted [ ]. During matches played in the European cup the injury is low in comparison to that observed during matches played in the League [4 ]. However, the consequences of matches played in the European cup on the injury per season are not well known either. To answer this question, a comparison between seasons whether or not the team played in the European cup seemed necessary. A few studies have examined the effects of the different playing positions (goalkeeper, defender, midfield and forward) on and severity of injury [6 ]. Some studies report more frequent injuries in forward [4, 9 ], defender [8 ] or goalkeeper [ ] positions while others find no difference between playing positions [6 ]. However, the number of players included according to their playing position is limited in these studies. An investigation of injury during several seasons allows inclusion of more soccer players and increases the amount of information collected. To obtain good results in competition, soccer players have to be talented, well trained and healthy. If too many injuries are sustained, team results can decrease because injury is then the single major factor decreasing player availability [4 ]. To confirm this assumption we investigated the relationship between injury and championship rankings. The aim of this prospective study of injury in professional soccer players during 5 seasons was to describe and examine: ) injury rate per seasons whether or not the team played in the European cup ) injury according Dauty M, Collon S. Incidence of Injuries in Int J Sports Med ; : 965 969

966 Clinical Sciences to playing position; ) the relationship between injury and the rank of the team at the end of each national soccer championship. Material and Methods In this cohort study, the of injury was investigated in professional soccer players in a single French professional club, the Football Club of Nantes. All the data were recorded prospectively during 5 seasons by sports physicians from the 995 996 to the 9 season. Ethics approval was obtained from the internal review board of the sampled football club and the study was performed in accordance with the ethical standards of the International Journal of Sports Medicine [ 7 ]. To ensure team and player confidentiality, all performance data were anonymized before analysis. Inclusion criteria for the study were defined by the selection of soccer players who participated in at least one match of the French championship during the sports season. The mean squad size over the 5-season period was 7 ± 6 players who were categorised into of the 4 individual playing positions: goalkeeper, defender, midfield and forward. Data were collected from the entire 995 996 to 9 seasons. During each season, matches played in the European or in the Domestic Cup were taken into account as time of exposure to potential injury. The club participated in the UEFA Champions League in 995 996 and, in the UEFA cup in 997 998, 999 and, but dropped to the French League during the 7 8 and 9 seasons.the number and the intensity of matches played in competition were thus different between seasons. All injuries were prospectively diagnosed the day after games by of the club s sports physicians and recorded in the professional sport injury register [ 7 ]. Injury was defined as one received during training or match-play and that prevented the injured party from participating in normal training for more than 7 h including the day of the injury [ 8, 9 ]. The injury location was clinically documented and the muscle injuries of the lower limbs were particularly studied because of their frequency [ ]. The player was considered injured until he was able to participate in collective training and was ready for match selection. Injury severity was categorized according to the definitions used on English and Swedish professional soccer players, as major (more than 8 days), moderate (7 8 days) and minor (less than 7 days) [, 5, 8, 9 ]. Slight ( days), minimal ( days) and mild (4 7 days) injuries were considered as minor injuries. A recurrent injury was taken into account as an independent injury. The exposure time per month was recorded a posterio by the physical trainer and could not be correlated to the respective proportion of endurance and technical training during the same period. The precise date of each injury was recorded to examine monthly variations in injury during the sports season. The mechanism, the cause of injury, and the injury context in match or during training periods were not recorded because attendance of a member of the medical staff is not always mandatory [ ] during training. It was deemed too unreliable to ask the players or coaching staff to report back to the medical centre. Statistical analysis was conducted using a SPSS 4. software (SPSS Inc. Chicago, IL, USA). Results are presented as means and standard deviations (mean ± SD). Injury is reported as injuries per h of exposure [, 4 ]. A Kruskal-Wallis two-way analysis of rank variance was used to compare injury s between seasons and according to the playing position or according to the severity of injuries during the 5-season period. Follow-up univariate analysis using Tukey s HSD test was used when appropriate. The relationships between total injury according to the severity of injuries or according to the team s rank in the French championship were explored using Pearson s product-moment correlation. To establish this last relationship, injuries which arose during the European or the Domestic cup were excluded. The seasons with and without matches played in the European cup were compared using t-test after variance analysis by a Levene test. The level of accepted statistical significance was set at p <.5. Results During the 5-season period, a total of 9 injuries were reported in 7 professional soccer players (height: 8 ± 5 cm; weight: 76 ± 7 kg). The injury rate per h of exposure was 4.7 ± 5. According to the severity of injuries, the injury rate per h of exposure was.6 ±. for minor injuries,.5 ±.4 for moderate injuries and.5 ±.66 for major injuries. The comparison of injury s between seasons showed no significant difference except for the 8 9 season (p <.) ( Table ). During a season, moderate injury occurred more frequent than that of minor or major injury. No difference was found according to playing positions on total injury ( p =.56) or on injury severity ( p =.66, p =.4 and p =.9 for minor, moderate and major injury, respectively) ( Table ). However, muscle injury doubled in 5 years. It was.9 per h of exposure in 995 996 and reached. in 9 with a maximum of.84 in 7 8 ( Fig. ). Hamstring injury represented the most frequent muscle injury. Muscle injuries of the lower limb increased during the 5-season period while other injuries of the lower limb, the upper limb, the head and the trunk did not increase ( Fig. ). No difference was found according to playing positions. During the 5-season period, January was the month with the highest injury rate ( Fig. ). No correlation was found between the total injury and the rank of the team at the end of each season ( Fig. 4 ). The injury according to injury severity (minor, moderate or major) was not correlated to these parameters either. The injury of seasons, when matches played in the European cup were played, was not different from that observed during seasons when matches were played only in the League and the Domestic cup (4 ± 4. vs. 5. ± 5.4; p =.). Discussion The definition of injury and injury severity used in this study followed that of other epidemiologic studies on elite soccer players [8,,, 6, ]. Injury was well documented because French law requires that all work related injuries occurring in a professional soccer team be reported. The duration of exposure is well documented because training and match scheduling is essential to the management of a sports season. Results indicated an overall injury rate ranging from.5 to 8.8 with a mean of 4.7 per h of exposure. In comparison, Walden et al. found an injury of 7.6 during consecutive seasons in Dauty M, Collon S. Incidence of Injuries in Int J Sports Med ; : 965 969

967 Season n Age Matches in National championship/ season/players National championship rank Injury ( h of exposure) 995 96 5. ±.7 ± 7 4.4 ± 4.4 996 97 8 5. ± 8 ± 5.69 ± 7.48 997 98 5 4 ± 4. 6 ± 4.9 ±.5 998 99 7.5 ±.8 6 ± 7.96 ±.4 999.5 ±.7 5 ±.59 ±.5 4. ±. 7 ± 4. ±.6 7 4. ± 4 6 ±.5 ±.5 6.9 ±. 9 ± 9.89 ±.9 4 6 4. ± 4 9 ± 6 4.75 ± 4.7 4 5.9 ±.4 ± 7 4.8 ± 5. 5 6 5.9 ±.4 7 ± 9 4 4. ± 4.6 6 7. ±.5 9 ± 6. ± 7. 7 8 6 4. ± 4. 7 ± (League ) 5.45 ± 5.44 8 9 5.4 ± 4.7 6 ± 9 8.8 ± 7.9** 9 5.6 ± 4.7 8 ± 5 (League ) 5. ± 4.76 total mean 7 ± 6 4. ± 4 7 ± ± 6 4.7 ± 5.4 **p <. participation in the European Cup Table Yearly injury over the 5-season period. elite professional Swedish soccer teams [ ]. Hawkins et al. reported an average injury rate of 8.5 in 4 English League teams over a 4-season period [8 ]. This difference could be explained by the fact that injury soars to about injuries per h of match-play and seems to increase with the playing level [ ]. The risk of injury may differ between countries, with a higher risk for English and Dutch teams in comparison to elite Swedish or Danish teams [4 ]. Regional differences on the risk of injury may be ascribed to several factors such as differences in seasonal team compositions, training intensity, playing style, tactics, referee judgments, weather and pitch conditions, and the way the medical staff works [ ]. The influence of these factors has not yet been established. Playing intensity during the European Cup matches does not seem to have influenced injury per h of exposure. In seasons during which matches in the European Cup were played, the injury (from.5 to 4) was not superior to that of other seasons (from.8 to 8.8). This result can be explained by the fact that injury was not associated to the number of days separating games [ 4 ]. In the same way, players who had international commitments during a given season did not have a higher risk of injury [ 9 ]. Injury rate did not depend on the team s final rank in the French championship. During the 8 9 season, the injury rate was very high (8.8 injuries per h of exposure) and corresponded to the decline from the French League to the League. However, it was not possible to know if this result was a cause or a consequence, because during the 7 8 season the same decline was observed and the total injury was much lower (5.4 injuries per h of exposure) and comparable to that of 996 997 season during which the team ranked third in the French League. The lowest injury (.5 injuries per h exposure) was observed during 999 and seasons during which the team respectively ranked and in the French League. The total injury was not related to the final ranking in the French championship. Various authors have already underlined the possibility of significant inter-season variation in injury rate over a - and 7-seasons period [, 5 ]. These findings may reflect natural variations across seasons or differences in the Table Playing position Total injury according to playing positions. n Players Injury ( h of exposure) 95 %CI goalkeeper 5 4.6 ± 6.6.54 6.68 defender 55 5.4 ± 5.5 4.5 6.4 midfielder 5 4.6 ± 4.9.5 4.99 forward 5 4.9 ± 4.74.68 5..5.5.5 995 96 997 98 999 Total muscle injury Hamstring injury Quadriceps injury 4 5 6 7 8 9 Calf injury Adductor injury Fig. Muscle injury (per h of exposure) during the 5-season period. Dauty M, Collon S. Incidence of Injuries in Int J Sports Med ; : 965 969

968 Clinical Sciences.5.5.5 995 96 996 97 997 98 998 99 Muscle injury Lower limb injury 999 4 4 5 5 6 Upper limb 6 7 7 8 8 9 9 Head and trunk injury Fig. Injury (per h of exposure) during the 5-season period according to injury location. Total Injury 6 5 4 July August September October November December January February March April May Fig. Seasonal injury (per h of exposure) variation during the 5-season period. French Championship's rank 8 6 4 8 6 4 5 5 5 Total Injury Incidence (Mean and Standard deviation) Fig. 4 Total injury ( h of exposure) and the French championship final rank of the team for each sports season. study environment. Changes in coaching staff and training methods or player turnover may also explain this variation [ 6 ]. The effect of injury can be considered in relation to its severity. The result of the present study differed from those previously reported by Junge et al. in which compared youth players from European regions [ ]. More moderate injuries and less major injuries were described with no correlation to the playing position. However, major injuries always required a lay-off of at least months and sometimes more if surgical treatment was necessary. Various periods in a season have been linked to injury [9, ]. Depending on different authors, periods were identified with a highest : in August at the beginning of the competition period ( Fig. ), [9 ] and in November and March [ 4 ]. In our study, total injury was highest in January. This winter month corresponds to a return to competition after a midseason break of 5 days. It has been suggested that this peak is due to the fact that players have an intensive and short period of time to recover an appropriate level of fitness to withstand the stresses associated with competitive soccer [ 4 ]. This observation was in accordance with the results of different studies which have shown an increase in injury after the midseason summer break when players returned to training and competition [5, 9 ]. In contrast, the injury was very low in May perhaps because there were no overuse injuries [4, ] or few injuries during competition [8 ]. June corresponded to a period of rest without injury. July was also not associated with a high injury although following a vacation break because this month corresponds to a long period of gradual physical and psychological preparation free of competition and with good weather conditions for playing [ 8 ]. Various studies have looked into the influence of playing positions on injury [9, 8,, 6, ]. Le Gall et al. found no difference between playing roles and age groups in elite youth soccer players [ 5 ]. In elite adult players the same author found a higher of muscle strain in the centre-forward players. Senior English professional defenders sustain more injuries during match play [ 8, 8 ]. For other authors, professional goalkeepers have significantly more upper body and hand injuries compared to outfield players [9 ]. In fact, comparisons between populations are difficult because study designs differ in identifying the 6 different playing positions. Our study has shown no difference in total injury according to playing positions. This can be explained by the practice of modern soccer in which a given playing position may change during a game. For example, the lateral fullbacks play in a defender position when the ball is lost and in a forward position when the team leads the game. In the same way, the fact that defenders and forwards are repeatedly in opposing roles with the adverse team players increases physical contact and the need for explosive anaerobic activity causing intrinsic injuries, such as muscle injuries [ 6, ]. In the case of the goalkeeper role, the number of players occupying this specific position may not have been sufficient to reveal significant differences in injury. The most common type of injury reported was muscle injury. During the 5-year period, the muscle injury rate increased progressively from less than per h of exposure from 995 to to over after. In contrast, the of other types of injury did not differ during the same period. Hamstring and quadriceps muscle injuries occurred very frequently with an of.7. in accordance with the results reported by Hägglund et al. (from.7.) [ 5 ]. A similar was Dauty M, Collon S. Incidence of Injuries in Int J Sports Med ; : 965 969

969 reported by Carling et al. with significant variations between seasons during a 4-season period (. 5.5) [ 4 ]. The highest rate reported in their study concerned the centre-forward position but all the playing positions had rates similar to those of our study. The main limitations of our study is that the cohort included soccer players from a single club and the injury context in match or during training period was not separately documented. The fact that data were recorded by different sport physicians can represented a limit of the study but only in terms of duration of prescribed sports rest. Similar investigations are needed with a larger sample of clubs to increase statistical power. It would have been interesting to have detailed information combining gamespecific and medical risk factors for injury, as well as information on the mechanisms involved in soccer-play injuries [ ]. Nevertheless, the present study gave worthwhile results in terms of soccer injuries that can be compared to current and future sports research. Conclusion In professional soccer players, the total injury did not vary significantly over a 5-season period except for the muscle injury rate which increased season after season independent of playing positions, of the matches played in the European cup per season and of the final rank of the team in the French national championship. However, inter-season variations may occur. To obtain more explanations about soccer injuries, future epidemiologic research should be carried out in accordance with international recommendations to record more medical information during training and matches. References Arnason A, Sigurdsson SB, Gudmundsson A, Holme I, Engebretsen L, Bahr R. Risk factors for injuries in football. Am J Sports Med 4 ; (Suppl ): 5S 6S Arnason A, Tenga A, Engebretsen L, Bahr R. 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