Soccer injuries in Iceland

Scand J Med Sci Sports 1996: 6: 40-45 Printed in Denmurk . AN rights reserved

Copyr igh t 0 Munksgaard 1996

Scandinavian Journal of MEDICINE & SCIENCE

I N S P O R T S ISSN 0905-7188

Soccer injuries in Iceland Arnason A, Gudmundsson A, Dahl HA, Johannsson E. Soccer injuries in Iceland. Scand J Med Sci Sports 1996: 6: 4045. 0 Munksgaard, 1996

We investigated the frequency, cause and location of injuries in Icelandic elite soccer in 1991. The incidence of injuries for the individual player was 34.825.7 per 1000 game-hours and 5.9?1.1 per 1000 practice-hours. The most common types of injuries were muscle strains (29%), ligament sprains (22%), contusions (20%), and other injuries (29%). The frequency of reinjury was markedly high, where 44% of the strains and 58% of the sprains were registered as reinjuries. Strains occurred mainly during sprinting, sprains by tackling, and contusion during other contact. Signifi- cantly more injuries occurred on artificial turf than on grass or gravel in correlation to number of hours in games and practices. Teams who had the longest pre-season preparation period obtained significantly fewer injuries during the season.

Soccer is the most popular sport in Europe (1, 2). In Iceland about 9% of the population are registered soccer players, making soccer the largest organized sport in the country. Soccer is a contact sport char- acterized by short and quick movements such as sprinting, sudden acceleration or deceleration, cutting, pivoting, shooting and kicking. Tackling and collision are also common (3) . The average distance run by an elite soccer player is about 10 km during one game, a major part of which is at high work intensity ( 3 ) . Elite soccer players therefore need to be in very good physical condition, and it is important for the coaches to cover many different elements in the training. Previous studies have shown that soccer players are responsible for approximately 50-60% of all sports-related injuries in Europe (4, 5). In view of this, it is necessary for the soccer players to train continuously for the major part of the year, and the training must include preventive measures.

The purpose of this study was to investigate the frequency and cause of injuries in Icelandic male elite soccer players during one season.

Material and methods Ten male teams take part in the Icelandic elite soccer division. Out of these, 5 teams with a total of 84 players (mean age 25, range 18-34 years) were chosen to participate in this study. The selection of teams

A. Arnasonl A. Gudmundssonl, H. A. Dah12.g, E. J6hannsson2g3 ’Icelandic College of Sport and Physical Education, Laugarvatn, Iceland, *Norwegian University of Sport and Physical Education, Oslo, 3Department of Anatomy, Institute of Basic Medical Sciences, Oslo, Norway

Key words: soccer; soccer injury; sports injury; epidemiology

Arni Arnason, Icelandic College of Sport and Physical Education, 840 Laugarvatn, Iceland

Accepted for publication June 7, 1995

was based on geographical distribution and on the results from 6 previous seasons. The soccer season starts in the middle of May and lasts until the middle of September.

In our study we have chosen to use the same injury definition as Lewin (6) : a soccer player was defined as injured if he was unable to participate in a match or training session because of an injury incurred in soccer. The player was defined as injured until he was able to comply fully with all instructions given by the oach.

The injuries were classified in 4 categories according to the length of absence from games and training sessions: less than 1 week, 1-2 weeks, 2 4 weeks and more than 4 weeks.

In April the players were tested with regard to muscle tightness and mechanical stability of the ankles and the knees. Range of motion (ROM) was measured in accordance with Ekstrand et al. (7) for hip flexion (with straight knee), hip extension, hip abduction, knee flexion (in the prone position with the hip straight) and ankle dorsiflexion (with straight knee). A Myrin flexometer was used in all of these measurements except for hip abduction where a double protractor goniometer was used. These measurements were all performed by the same physical therapist in controlled circumstances. The method and its reliability are described by Ekstrand et al. (7).

The tests for mechanical stability (medial, lateral,

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Soccer injuries in Iceland

Table 1. Injury rates per 1000 hours of soccer

Injury rate Number of

Type of injury injuries Soccer* Game Practice

drawer test) of the ankles and knees were all performed by hand by one experienced physical therapist.

From April 1 until the end of the season, Septem- ber 18, 1991, the injuries were registered by a physical therapist, physician or coach on a particular injury registration form. We registered when and where the injury occurred, the type and location of the injury and whether it was a reinjury or not. For acute injuries, we registered the playing situation when injuries occurred, at what time in the game or practice the injuries occurred, the actual playing ground and use of shinguards. Overuse injuries were registered with regard to playing ground, training intensity etc. as well as changes in these factors. Moreover, duration of absence from game and practice because of the injury was registered. All injuries were examined and diagnosed by a physician or by a physical therapist. Finally, every practice session and game was registered by the coach in a training diary, with regard to playing surface and participation by the individual player. The total time each player spent in games and training was registered, and the players also answered a questionnaire about previous injuries.

The statistical analyses were performed with two- group unpaired t-test to compare the difference in ROM between injured and non-injured players. Chi- square was used to compare the incidence of injuries in stable and unstable ankles and knees.

Results During the period of this study, 60 of the players (71%) incurred 129 injuries. The population at risk was 84, and the incidence of injury for the individual player was 12.421.4 per 1000 hours of soccer: 34.825.7 per 1000 game-hours and 5,921.1 per 1000 practice-hours. On average one injury occurred in 2 games and 12 practice sessions. Eighty- five injuries by 49 players were registered with regard to type, location and cause of injury. Seventy (82%) of the injuries were located in the lower ex- tremities. Seventy-seven (9 1%) of the injuries were acute and 8 (9%) were overuse injuries. Forty-four injuries by 11 players were insufficiently documented and have been classified as such. They are not discussed further here.

Types and locations of injuries

Strains in the muscle-tendon unit were the most frequent type of injury (29%). The incidence for the individual player was 2.620.7 per 1000 hours of soccer (Table 1). Most of the strains lasted less than 1 week (n= 1 l), or 1-2 weeks (n=9). Most of the strains occurred during games. Significantly (P<0.02) more

~ ~

Muscle strains Hamstrings

Ligament sprains Ankles

Contusions Other

Total

25 (29%) 14 (16%) 19 (22%) 13 (13%) 17 (20%) 24 (28%)

85 (100%)

2.620.7 1 5 2 0 . 5 2.0+0.5 1.320.4 1.720.4 2.620.7

12.4tl.4

8.222.5 4.1 21 .6 6.822.0 4.421.4 4.321.3 3.651.4

34.825.7

0.820.3 0.420.3 0.320.2 0.1 20.1 0.7 t 0.3 2.220.7

5.921.1

Soccer=game and practice

strains occurred in the second half of the games and practices than in the first half.

Ligament sprains accounted for 22% of the injuries. Most of them occurred during games. The incidence was 2.0?0.5 per 1000 hours of soccer (Table 1). The majority of the ankle sprains was located in the lateral ligaments and lasted less than 1 week (n=6) or 1-2 weeks (n=4). Most of the knee sprains occurred in the medial or lateral collateral ligament (n=4) and lasted 2 4 weeks. One injury affected both the anterior cruciate ligament and the medial collateral ligament and lasted more than 4 weeks.

Contusions were 20%,, and the incidence was 1.720.4 per 1000 hours of soccer (Table 1); 59% lasted less than 1 week and 41% 1-2 weeks. Most (70'K) occurred during games.

Other types of injuries were 24 (28%). Of these, 8 were overuse injuries and 16 were acute, such as inter- vertebral locking, meniscal injuries or fractures. The details of incidence and location of the acute injuries are shown in Table 2.

Rein j u ry

Of 85 injuries, 30 (35%) were reinjuries (Fig. 1). Seven occurred less than 1 month after the previous injury. Five occurred 1-6 months after, 4 occurred 6-12 months after, and 14 of the reinjuries occurred more than 12 months after the previous injury. Forty-four percent of the muscle strains and 58% of the ligament sprains were reinjuries of the same type and location (Fig. 1).

Mechanism of the injuries

Fifty-one (66%) of the 77 acute injuries occurred during games and 26 (34%) during practice. Of the acute injuries, 44%" occurred during physical contact with another player, and 56% were non-contact injuries. The number of injuries incurred in different playing situations is shown in Fig. 2. The most common in-

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Arnason et al.

Table 2. Type and location of acute injuries in relation to playing situations when the injuries occur (n=77)

Contact injuries (n= 34) Noncontact injuries (n=43)

Type and location Other contact Shooting/ of injuries Tacklings than tacklings Sprinting kicking Cutting Other Total

Total muscle strain 1 0 14 7 2 1 25 Posterior thigh 1 0 12 1 0 0 14 Anterior thigh 0 0 0 3 1 1 5 Groin 0 0 1 2 1 0 4 Other location 0 0 1 1 0 0 2

Total ligament sprain 13 1 0 1 2 2 19 Ankles 8 1 0 0 2 2 13 Knees 5 0 0 0 0 0 5 Foot 0 0 0 1 0 0 1

Total contusions 4 12 0 0 0 I 17 Anterior thigh 2 5 0 0 0 1 8 Posterior lower leg 0 4 0 0 0 0 4 Knee 1 1 0 0 0 0 2 Other location 1 2 0 0 0 0 3

Other 3 0 0 3 1 9 16

Total 21 13 14 11 5 13 77

juries during tackling were ankle sprains, knee sprains and contusions (Table 2). Of 13 ligament sprains incurred during tackling, 11 occurred during the first half of a game.

Playing surface and equipment During the study, significantly (P<O.Ol) more injuries occurred on artificial turf than on grass or gravel in

16 I ~

14

12

1 0 Number of

injuries 6 4

2 0

Ankle Knee Hamstrings Quadriceps Groin Low back sprains sprains strams strains strams inlures

Fig. 1. The number of injuries and reinjuries with regard to type and location

relation to number of hours in soccer (games and practices) (Fig. 3 ) . There was no significant difference in type and location of injuries between different playing surfaces.

Ninety-seven percent of the players used shinguards in every game and 38% in every practice session, and no contusions were seen anteriorly in the leg and only one contusion occurred at the lateral malleolus.

Muscle tightness In this study there was no significant difference in muscle tightness between players who strained their muscles and those who did not. Players who earlier had strained their quadriceps had significantly (FY0.03) shorter rectus femoris, than those who never had strained before. The players had significantly (P<0.02) more flexibility in the nondominant leg than in the dominant leg in hip abduction and hip

2 s Injuries per 2o

1000 hours of soccer

10

S 0

Gravel Artificial tur f Grass

Fig. 3. The incidence of injuries for the individual player per 1000 hours of soccer on different playing surfaces

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extension. The players who had participated in other kinds of sport earlier had significantly (P<0.05) more flexibility in hip extension than players who only had played soccer.

Joint instability

Lateral instability was found in 33% of the ankles and anterior instability in 25% of the ankles. Al- though nine of 13 ankle sprains affected ankles with a history of previous sprain, there was no significant difference in the number of ankle sprains between ankles with lateral or anterior instability and those who were stable. Medial instability was found in 21% of the knees and lateral instability in 17% of the knees. Anterior instability was found in 2% of the knees. Significantly (P<0.02) more injuries occurred in knees with medial instability than in stable knees.

Coaching factors

In spite of differences in the pre-season preparation period, the number of games (3 1.2?2.9) and practice sessions (86.627.1) in the season was almost similar between the different teams. The 2 teams who had longer pre-season preparation period obtained significantly (fYO.01) fewer injuries during the season than the 3 other teams. These 3 teams that started later had coaches with less education in sport.

A typical warm-up by all the 5 teams included run- ning, ball exercises and a short period of stretching, often individually performed and not controlled by the coach. No cool-downs were seen after games, but after some of the practices the teams coached by physical educators used cool-down consisting of run- ning and stretching. Some of the players in the other teams used stretching after the practices. In these cases stretching was commonly performed inad- equately, of too short duration and performed individually without control by the coach.

Discussion The results of previous epidemiologic and traumatol- ogic studies in soccer are equivocal, because both the injury definition and the way information is collected and recorded vary between the studies (1, 6, 8-12). In most studies the injury rate is given in absolute num- bers or in percent, without regard to the time spent in game and training. Because of this, exact comparison between different studies can be difficult (1, 5, 13). In the present study, the incidence of various injuries is given per 1000 hours of game, practice or game and practice combined for each player. This method ac- counts for the time the players are at risk and makes it easier to compare injury rates in different studies.

In several studies, a soccer player is defined as injured until he is able to participate in games or practice (1, 9, 14). In the present study, we used the broader definition presented by Lewin (6). This can possibly result in more lasting injuries compared to the study by Ekstrand (9). For example, we found a higher rate of muscle strains and ligament sprains lasting more than 4 weeks, but fewer lasting less than one week than Ekstrand (9). Effective treatment and sufficient rehabilitation is necessary to get the players quickly back on the team after an injury and to avoid reinjuries. The long duration of injuries together with a relatively high incidence of reinjuries in our material may indicate insufficient medical support from the teams. Two of the five teams in this study have no special contact with medical professions.

Short pre-season preparation period by some of the teams and coaches with poor education in sport can be risk factors for injuries. Inadequate or no cool down and a lack of adequate stretching may predis- pose to tight muscles and longer recovery time after each game or practice (9, 15, 16).

The rate of injured players was higher in this study than in most previous studies ( I , 12, 17, 22). Few studies have reported a similar or higher frequency of injured players (6, 9), although these studies lasted longer than the present study. One explanation for this may be that the season is very short in Iceland, allocating only short time for rest and recuperation between the games. Nielsen & Yde ( l ) , and Ek- strand & Tropp (17) have shown that the incidence of injuries during games is higher in the top divisions than in the lower divisions. The reason for this can be that games and practices are more tightly sched- uled and the work intensity is higher among players in the top divisions. On the other hand, the incidence of injuries per 1000 practice-hours in the present study was similar to most other studies (1, 9, 17).

In the present study, 29% of all injuries were muscle strains. This is substantially higher than reported by Ekstrand (9), but similar to that found by Lewin (6). Our results differ from the others by having much more strains in the hamstrings. The majority of these occurred in sprint situations, which is in agreement with Arge (16) and Ekstrand (9). Significantly more muscle strains occurred in the second half of the game or practice than in the first half, and it is tempt- ing to assume that the short pre-season preparatory period used by many of the teams leaves the players in an insufficient physical condition when the pre-season training games start. In addition, progressive muscle fatigue towards the end of a game, for example because of depression of muscle glycogen (1 8) may increase the risk of injury.

Although many studies report a possible relationship between muscle tightness and muscle strains (1 5, 16, 19), very few studies have been able to prove this

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Arnason et al.

relationship (9). In the current study we found no correlation between muscle tightness and muscle strains, possibly because of many other confusing factors and the relatively low number of participants in this study.

Quadriceps tightness in players with a history of previous strains in this muscle group indicates insufficient rehabilitation or stretching after these injuries. Compared to other studies (15), a high frequency of recurrent strains (44% of the muscle strains) was found in the present study, indicating insufficient rehabilitation or too early return to high-intensity training or games after the acute injury.

Muscle tightness is common in soccer players and may be the result of the high demands placed on muscle strength and power in this sport. Moreover, insufficient attention is often paid to flexibility training (9, 15). Significantly less flexibility in the dominant leg compared to the nondominant in hip abduction and hip extension in the present study, and significantly lower flexibility in hip extension in players who had not participated in other kinds of sport, support the assumption that soccer training may pre- dispose to muscle tightness.

There is reason to believe that the cold and windy weather in Iceland may increase the risk of muscle strains, but this factor has not been clearly documented in previous studies (1 5) .

Ligament sprains were less frequent in this study (22%) than in earlier studies (6, 9, 20). This difference is probably due to relatively fewer knee sprains in our study. However, the knee injuries we observed (especially ligament and meniscal injuries) lasted longer than other types of injuries, and this is in agreement with Ekstrand (9). It has been suggested that instability because of previously sprained ankles or knees is a risk factor for renewed ankle or knee sprain (9, 13, 17). Compared to other studies (1, 17), recurrent ankle sprains were frequent in the present study (69%). We found no difference in the rate of ankle sprains, however, between ankles with mechanical instability and those who were stable. The reason could be that we only tested mechanical stability but not functional stability, and in Iceland the use of taping and braces is common for mechanically unstable ankles in soccer.

Tackling, which was the most common cause of ligament sprains, will always carry an inherent risk of injury in soccer. Hopefully, the new rules, prescribing the red card for rough tackling from behind, will re- duce the incidence of serious ligament injuries in soccer in the future.

The overuse injuries were less frequent in this study than in most other studies (1, 9). A reasonable explanation for this can be that most of the overuse injuries observed by others, occurred in the pre-season preparation period, but only the latest part of this period was included in the present study.

A possible relationship between injuries in soccer and the playing surface has been discussed in many studies (13, IS, 21-23). According to Ekstrand & Nigg (22), two main factors affect surface-related soccer injuries: the stiffness of a surface and the friction between surface and shoe. In the present study two fields covered with artificial turf were used. Both of them were stiff and with high friction, especially in dry weather, which may explain why the frequency of injury was significantly higher on those fields than on grass or gravel.

References 1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

Nielsen AB, Yde J. Epidemiology and traumatology of injuries in soccer. Am J Sports Med 1989: 17: 803-7. Nilsson S, Roaas A. Soccer injuries in adolescents. Am J Sports Med 1978: 6: 358-61. Ekblom B. Applied physiology of soccer. Sports Med 1986: 3: 50-60. Franke K. Traumatologie des Sports. Berlin: VEG Verlag, 1977. Keller CS, Noyes FR. Buncher CR. The medical aspects of soccer injury epidemiology. Am J Sports Med 1987: 15:

Lewin G. The incidence of injuries in an English professional soccer club during one competitive season. Physiotherapy 1989: 75: 601-5; Ekstrand J, Wiktorsson M, Oberg B, Gillquist J. Lower extremity goniometric measurements: a study to determine their reliability. Arch Phys Med Rehabil 1982: 63:

Alles WF, Powell JW, Buckley W, Hunt EE. The national athletic injuryiillness reporting system 3-year findings of high school and college football injuries. JOSPT 1979: 1:

Ekstrand J. Soccer injuries and their prevention. Linkop- ing: Linkoping University Medical Dissertations No. 130, 1982. Hoff GL, Martin TA. Outdoor and indoor soccer: Injuries among youth players. Am J Sports Med 1986: 14: 231-3. Sadat-Ali M, Sankarian-Kutty M. Soccer injuries in Saudi Arabia. Am J Sports Med 1987: 15: 50&2. Schmidt-Olsen S, Biinemann LKH, Lade V, Brasscre JOK. Soccer injuries of youth. Br J Sports Med 1985: 19: 161- 4. Ekstrand J, Gillquist J. Soccer injuries and their mechan- isms: a prospective study. Med Sci Sports Exerc 1983: 15:

Sullivan JA, Gross RH, Grana WA, Garcia-Moral CA. Evaluation of injuries in youth soccer. Am J Sports Med 1980: 8: 325-7. Inklaar H. Soccer injuries 11. Aetiology and prevention. Sports Med 1984: 18: 81-93. Arge JC. Hamstring injuries. Proposed aetiological factors, prevention, and treatment. Sports Med 1985: 2: 21- 33. Ekstrand J, Tropp H. The incidence of ankle sprains in soccer. Foot Ankle 1990: 11: 4 1 4 . Bangsbo J. The physiology of soccer. Copenhagen: Univer- sity of Copenhagen, August Krogh Institute, 1993. Arge JC, Baxter TL. Musculoskeletal profile of male col- legiate soccer players. Arch Phys Med Rehabil 1987: 68: 147-50. Albert M. Descriptive three year data study of outdoor

230-7.

171-5.

103-8.

267-70.

44


and indoor professional soccer injuries. Athletic Training 1983: 18: 218-20.

21, Berger-Vachon C, Gabard G, Moyen B. Soccer accidents in the French RhBne-Alpes Soccer Association. Sports Med 1986: 3: 69-71. 15.

22. Ekstrand J, Nigg BM. Surface-related injuries in soccer. Sports Med 1989: 8: 56-62.

23. Fried T, Lloyd GJ. An overview of common soccer injuries. Management and prevention. Sports Med 1992: 14: 269-

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Soccer injuries in Iceland