Exercises to prevent lower limb injuries in youth sports: cluster rand
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《英国医生杂志》
1 Oslo Sports Trauma Research Center, Norwegian University of Sport and Physical Education, 0806 Oslo, Norway
Correspondence to: O E Olsen odd-egil.olsen@nih.no
Abstract
Regular physical activity reduces the risk of premature mortality in general and of coronary heart disease, hypertension, colon cancer, obesity, and diabetes mellitus in particular.1 2 However, participation in sports also entails a risk of injury for all athletes, from the elite to the recreational level. Studies from Scandinavia document that sports injuries constitute 10-19% of all acute injuries seen in emergency departments, and the most common types are knee and ankle injuries.3 Serious knee injuries, such as injuries to the anterior cruciate ligament, are a growing cause of concern. The highest incidence is seen in adolescents playing pivoting sports such as football, basketball, and team handball. In these sports, women are three to five times more likely to contract a serious knee injury than men.4-6
Injuries to the anterior cruciate ligament may require surgery, always entail a long rehabilitation period, and drastically increase the risk of long term sequelae.7 Although treatment methods have advanced notably, there is no evidence to show that repair of a ruptured anterior cruciate ligament or isolated cartilage lesions prevents early development of osteoarthritis.7 Effective methods for preventing injuries therefore need to be developed.
Some studies report promising results, indicating that it may be possible to reduce the incidence of knee and ankle injuries among adults8-10 and adolescents.11-14 However, these studies are small and mainly non-randomised, with important methodological limitations. Prospective randomised intervention studies are therefore needed, especially among children and adolescents, to assess the efficacy of interventions aiming to reduce injuries.
We conducted a randomised controlled trial to investigate the effect of a structured programme of warm-up exercises used to prevent acute injuries of the lower limb in young people playing sports. To minimise overlap within clubs, we used a cluster design.
Methods
Figure 3 shows the flow of clubs and players through the trial. Players in the two groups were similar in sex distribution, age, and dropout rates (table 1). All but eight (13%) of the clubs in the intervention group used the programme of warm-up exercises used to prevent injuries during the study period. Also, 13 (22%) of the clubs in the control group used specific exercises intended to prevent injuries (including training on the balance mat and wobble board) as a part of their training.
Fig 3 Flow of club clusters and players through the study. After randomisation, two clubs in the control group withdrew from participating in the Norwegian Handball Federation league (no players played for these clubs), and one club in the intervention group declined to participate in the study. The players (n=49) in these clubs were excluded from the study
Table 1 Characteristics of participants and compliance of clubs. Values are numbers (percentages) of participants unless otherwise indicated
Box 3: Operational definitions used in the registration of injury
Reportable injury
An injury occurred during a scheduled match or training session, causing the player to require medical treatment or miss part of or the next match or training session
Player
A player was entered into the study if she or he was aged 15-17 years (born between 1 January 1985 and 31 December 1987), was registered on the club roster by the coach, and did not have a major injury at the start of the study
Return to participation
The player was defined as injured until he or she was able to participate fully in club activities (match and training sessions)
Type of injury
Acute—injury with a sudden onset associated with a known trauma Overuse—injury with a gradual onset without any known trauma
Severity
Slight—0 days of absence and able to participate fully in the next match or training session
Minor—absence from match or training for 1-7 days
Moderate—absence from match or training for 8-21 days
Major—absence from match or training for > 21 days
Exposure*
Match exposure—hours of matches
Training exposure—hours of training
In nearly all cases, players sustaining moderate or major injuries were examined by a doctor. If there was any doubt about the diagnosis the player was referred to a sport doctor or a sports medicine centre for follow up, which often included imaging studies or arthroscopic examination. In case of a slight or minor injury, the player was often examined only by a physical therapist or coach or not at all. None of the injured players was examined or treated by any of the authors, and we had no influence on the time it took a player to return to club activities.
Injury characteristics
During the eight month season, 262 (14%) of the 1837 players who were included in the study contracted a total of 298 injuries. Of these, 241 (81%) were acute injuries and 57 (19%) were overuse injuries. Table 2 shows the location of the most common body part injured, the type of acute and overuse injuries, and the age of the injured players.
Table 2 Most common body part injured, most common type of acute and overuse injuries, and age of the injured players. Values are numbers (percentages) of participants unless otherwise indicated
Effect of prevention
Significantly fewer injured players were in the intervention group than in the control group for injuries overall, lower limb injuries, acute knee or ankle injuries, and acute knee and upper limb injuries, whereas a 37% reduction in acute ankle injuries did not reach significance (table 3). The degrees of clustering at the club level (intracluster correlation coefficient) were estimated to be 0.043 to 0.071. The number needed to treat to prevent one injury varied from 11 to 59 players.
Table 3 Intention to treat analysis. Values are numbers (percentages) of injured players
The exposure in hours for the intervention group was 93 812 (11 210 hours spent in matches, 82 602 hours in training) and in the control group 87 483 hours (10 783 hours in matches, 76 700 hours in training). Table 4 shows the severity of injury for different types of injury. Injuries overall, acute injuries, and acute knee or ankle injuries differed significantly, whereas reductions in 7-53% for slight injuries and 18-59% in minor injuries did not reach significance. The overall difference in the incidence of match and training injuries was also significant, whereas acute injuries and acute knee or ankle injuries differed only for matches (table 5). The 13 control clubs using training exercises to prevent injuries had a significantly lower incidence of injuries than the clubs in the control group doing no prevention training (rate ratio: all injuries 0.48, 95% confidence interval 0.31 to 0.73, P < 0.001; lower limb injuries 0.35, 0.19 to 0.63; P = 0.001; acute injuries 0.47, 0.29 to 0.76; P = 0.002; acute knee or ankle injuries 0.22, 0.09 to 0.55; P = 0.001). No category of injury differed by sex.
Table 4 Numbers and severity of injuries
Table 5 Number of acute injuries, acute knee or ankle injuries, and incidence of injuries during matches and training. Incidence is reported as the number of injuries per 1000 player hours, with standard errors
Discussion
Pate RR, Pratt M, Blair SN, Haskell WL, Macera CA, Bouchard C, et al. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273: 402-7.
Fletcher GF, Balady G, Blair SN, Blumenthal J, Caspersen C, Chaitman B, et al. Statement on exercise: benefits and recommendations for physical activity programs for all Americans. A statement for health professionals by the Committee on Exercise and Cardiac Rehabilitation of the Council on Clinical Cardiology, American Heart Association. Circulation 1996;94: 857-62.
Bahr R, Kannus P, van Mechelen. Epidemiology and prevention of sports injuries. In: Kj?r M, Krogsgaard M, Magnusson P, Engebretsen L, Roos H, Takala T, et al. Textbook of sports medicine. Basic science and clinical aspects of sports injury and physical activity. Blackwell Science, 2003: 299-314.
Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer. NCAA data and review of literature. Am J Sports Med 1995;23: 694-701.
Myklebust G, Maehlum S, Engebretsen L, Strand T, Solheim E. Registration of cruciate ligament injuries in Norwegian top level team handball. A prospective study covering two seasons. Scand J Med Sci Sports 1997;7: 289-92.
Powell JW, Barber-Foss KD. Sex-related injury patterns among selected high school sports. Am J Sports Med 2000;28: 385-91.
Myklebust G, Bahr R. "When can I play again, Doc" vs. "Is it time to quit"—a critical look at return-to-play guidelines after ACL surgery. Br J Sports Med (in press).
Caraffa A, Cerulli G, Projetti M, Aisa G. Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training. Knee Surg Sports Traumatol Arthroscopy 1996;4: 19-21.
Bahr R, Lian O, Bahr IA. A twofold reduction in the incidence of acute ankle sprains in volleyball after the introduction of an injury prevention program: a prospective cohort study. Scand J Med Sci Sports 1997;7: 172-7.
Myklebust G, Engebretsen L, Braekken IH, Skjolberg A, Olsen OE, Bahr R. Prevention of ACL injuries in female team handball players - a prospective intervention study over three seasons. Clin J Sport Med 2003;13: 71-8.
Wedderkopp N, Kaltoft M, Lundgaard B, Rosendahl M, Froberg K. Prevention of injuries in young female players in European team handball. A prospective intervention study. Scand J Med Sci Sports 1999;9: 41-7.
Hewett TE, Lindenfeld TN, Riccobene JV, Noyes FR. The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study. Am J Sports Med 1999;27: 699-706.
Heidt RS Jr, Sweeterman LM, Carlonas RL, Traub JA, Tekulve FX. Avoidance of soccer injuries with preseason conditioning. Am J Sports Med 2000;28: 659-62.
Junge A, Rosch D, Peterson L, Graf-Baumann T, Dvorak J. Prevention of soccer injuries: a prospective intervention study in youth amateur players. Am J Sports Med 2002;30: 652-9.
Nielsen AB, Yde J. An epidemiologic and traumatologic study of injuries in handball. Int J Sports Med 1988:9: 341-4.
Lin DY, Wei DJ. The robust inference for the Cox proportional hazards model. J Am Stat Assoc 1989;84: 1074-8.
Ebstrup JF, Bojsen-Moller F. Anterior cruciate ligament injury in indoor ball games. Scand J Med Sci Sports 2000;10: 114-6.
Olsen OE, Myklebust G, Engebretsen L, Bahr R. Injury mechanisms for anterior cruciate ligament injuries in team handball: a systematic video analysis. Am J Sports Med 2004;32: 1002-12.
Holm I, Fosdahl MA, Friis A, Risberg MA, Myklebust G, Steen H. Effect of neuromuscular training on proprioception, balance, muscle strength, and lower limb function in female team handball players. Clin J Sport Med 2004;14: 88-94.
Hewett TE, Stroupe AL, Nance TA, Noyes FR. Plyometric training in female athletes. Decreased impact forces and increased hamstring torques. Am J Sports Med 1996;24: 765-73.
Mjolsnes R, Arnason A, Osthagen T, Raastad T, Bahr R. A 10-week randomized trial comparing eccentric vs. concentric hamstring strength training in well-trained soccer players. Scand J Med Sci Sports 2004;14: 311-7.
Chappell JD, Yu B, Kirkendall DT, Garrett WE. A comparison of knee kinetics between male and female recreational athletes in stop-jump tasks. Am J Sports Med 2002;30: 261-7.
Fagenbaum R, Darling WG. Jump landing strategies in male and female college athletes and the implications of such strategies for anterior cruciate ligament injury. Am J Sports Med 2003;31: 233-40.(Odd-Egil Olsen, research fellow1, Grethe)
Correspondence to: O E Olsen odd-egil.olsen@nih.no
Abstract
Regular physical activity reduces the risk of premature mortality in general and of coronary heart disease, hypertension, colon cancer, obesity, and diabetes mellitus in particular.1 2 However, participation in sports also entails a risk of injury for all athletes, from the elite to the recreational level. Studies from Scandinavia document that sports injuries constitute 10-19% of all acute injuries seen in emergency departments, and the most common types are knee and ankle injuries.3 Serious knee injuries, such as injuries to the anterior cruciate ligament, are a growing cause of concern. The highest incidence is seen in adolescents playing pivoting sports such as football, basketball, and team handball. In these sports, women are three to five times more likely to contract a serious knee injury than men.4-6
Injuries to the anterior cruciate ligament may require surgery, always entail a long rehabilitation period, and drastically increase the risk of long term sequelae.7 Although treatment methods have advanced notably, there is no evidence to show that repair of a ruptured anterior cruciate ligament or isolated cartilage lesions prevents early development of osteoarthritis.7 Effective methods for preventing injuries therefore need to be developed.
Some studies report promising results, indicating that it may be possible to reduce the incidence of knee and ankle injuries among adults8-10 and adolescents.11-14 However, these studies are small and mainly non-randomised, with important methodological limitations. Prospective randomised intervention studies are therefore needed, especially among children and adolescents, to assess the efficacy of interventions aiming to reduce injuries.
We conducted a randomised controlled trial to investigate the effect of a structured programme of warm-up exercises used to prevent acute injuries of the lower limb in young people playing sports. To minimise overlap within clubs, we used a cluster design.
Methods
Figure 3 shows the flow of clubs and players through the trial. Players in the two groups were similar in sex distribution, age, and dropout rates (table 1). All but eight (13%) of the clubs in the intervention group used the programme of warm-up exercises used to prevent injuries during the study period. Also, 13 (22%) of the clubs in the control group used specific exercises intended to prevent injuries (including training on the balance mat and wobble board) as a part of their training.
Fig 3 Flow of club clusters and players through the study. After randomisation, two clubs in the control group withdrew from participating in the Norwegian Handball Federation league (no players played for these clubs), and one club in the intervention group declined to participate in the study. The players (n=49) in these clubs were excluded from the study
Table 1 Characteristics of participants and compliance of clubs. Values are numbers (percentages) of participants unless otherwise indicated
Box 3: Operational definitions used in the registration of injury
Reportable injury
An injury occurred during a scheduled match or training session, causing the player to require medical treatment or miss part of or the next match or training session
Player
A player was entered into the study if she or he was aged 15-17 years (born between 1 January 1985 and 31 December 1987), was registered on the club roster by the coach, and did not have a major injury at the start of the study
Return to participation
The player was defined as injured until he or she was able to participate fully in club activities (match and training sessions)
Type of injury
Acute—injury with a sudden onset associated with a known trauma Overuse—injury with a gradual onset without any known trauma
Severity
Slight—0 days of absence and able to participate fully in the next match or training session
Minor—absence from match or training for 1-7 days
Moderate—absence from match or training for 8-21 days
Major—absence from match or training for > 21 days
Exposure*
Match exposure—hours of matches
Training exposure—hours of training
In nearly all cases, players sustaining moderate or major injuries were examined by a doctor. If there was any doubt about the diagnosis the player was referred to a sport doctor or a sports medicine centre for follow up, which often included imaging studies or arthroscopic examination. In case of a slight or minor injury, the player was often examined only by a physical therapist or coach or not at all. None of the injured players was examined or treated by any of the authors, and we had no influence on the time it took a player to return to club activities.
Injury characteristics
During the eight month season, 262 (14%) of the 1837 players who were included in the study contracted a total of 298 injuries. Of these, 241 (81%) were acute injuries and 57 (19%) were overuse injuries. Table 2 shows the location of the most common body part injured, the type of acute and overuse injuries, and the age of the injured players.
Table 2 Most common body part injured, most common type of acute and overuse injuries, and age of the injured players. Values are numbers (percentages) of participants unless otherwise indicated
Effect of prevention
Significantly fewer injured players were in the intervention group than in the control group for injuries overall, lower limb injuries, acute knee or ankle injuries, and acute knee and upper limb injuries, whereas a 37% reduction in acute ankle injuries did not reach significance (table 3). The degrees of clustering at the club level (intracluster correlation coefficient) were estimated to be 0.043 to 0.071. The number needed to treat to prevent one injury varied from 11 to 59 players.
Table 3 Intention to treat analysis. Values are numbers (percentages) of injured players
The exposure in hours for the intervention group was 93 812 (11 210 hours spent in matches, 82 602 hours in training) and in the control group 87 483 hours (10 783 hours in matches, 76 700 hours in training). Table 4 shows the severity of injury for different types of injury. Injuries overall, acute injuries, and acute knee or ankle injuries differed significantly, whereas reductions in 7-53% for slight injuries and 18-59% in minor injuries did not reach significance. The overall difference in the incidence of match and training injuries was also significant, whereas acute injuries and acute knee or ankle injuries differed only for matches (table 5). The 13 control clubs using training exercises to prevent injuries had a significantly lower incidence of injuries than the clubs in the control group doing no prevention training (rate ratio: all injuries 0.48, 95% confidence interval 0.31 to 0.73, P < 0.001; lower limb injuries 0.35, 0.19 to 0.63; P = 0.001; acute injuries 0.47, 0.29 to 0.76; P = 0.002; acute knee or ankle injuries 0.22, 0.09 to 0.55; P = 0.001). No category of injury differed by sex.
Table 4 Numbers and severity of injuries
Table 5 Number of acute injuries, acute knee or ankle injuries, and incidence of injuries during matches and training. Incidence is reported as the number of injuries per 1000 player hours, with standard errors
Discussion
Pate RR, Pratt M, Blair SN, Haskell WL, Macera CA, Bouchard C, et al. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273: 402-7.
Fletcher GF, Balady G, Blair SN, Blumenthal J, Caspersen C, Chaitman B, et al. Statement on exercise: benefits and recommendations for physical activity programs for all Americans. A statement for health professionals by the Committee on Exercise and Cardiac Rehabilitation of the Council on Clinical Cardiology, American Heart Association. Circulation 1996;94: 857-62.
Bahr R, Kannus P, van Mechelen. Epidemiology and prevention of sports injuries. In: Kj?r M, Krogsgaard M, Magnusson P, Engebretsen L, Roos H, Takala T, et al. Textbook of sports medicine. Basic science and clinical aspects of sports injury and physical activity. Blackwell Science, 2003: 299-314.
Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer. NCAA data and review of literature. Am J Sports Med 1995;23: 694-701.
Myklebust G, Maehlum S, Engebretsen L, Strand T, Solheim E. Registration of cruciate ligament injuries in Norwegian top level team handball. A prospective study covering two seasons. Scand J Med Sci Sports 1997;7: 289-92.
Powell JW, Barber-Foss KD. Sex-related injury patterns among selected high school sports. Am J Sports Med 2000;28: 385-91.
Myklebust G, Bahr R. "When can I play again, Doc" vs. "Is it time to quit"—a critical look at return-to-play guidelines after ACL surgery. Br J Sports Med (in press).
Caraffa A, Cerulli G, Projetti M, Aisa G. Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training. Knee Surg Sports Traumatol Arthroscopy 1996;4: 19-21.
Bahr R, Lian O, Bahr IA. A twofold reduction in the incidence of acute ankle sprains in volleyball after the introduction of an injury prevention program: a prospective cohort study. Scand J Med Sci Sports 1997;7: 172-7.
Myklebust G, Engebretsen L, Braekken IH, Skjolberg A, Olsen OE, Bahr R. Prevention of ACL injuries in female team handball players - a prospective intervention study over three seasons. Clin J Sport Med 2003;13: 71-8.
Wedderkopp N, Kaltoft M, Lundgaard B, Rosendahl M, Froberg K. Prevention of injuries in young female players in European team handball. A prospective intervention study. Scand J Med Sci Sports 1999;9: 41-7.
Hewett TE, Lindenfeld TN, Riccobene JV, Noyes FR. The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study. Am J Sports Med 1999;27: 699-706.
Heidt RS Jr, Sweeterman LM, Carlonas RL, Traub JA, Tekulve FX. Avoidance of soccer injuries with preseason conditioning. Am J Sports Med 2000;28: 659-62.
Junge A, Rosch D, Peterson L, Graf-Baumann T, Dvorak J. Prevention of soccer injuries: a prospective intervention study in youth amateur players. Am J Sports Med 2002;30: 652-9.
Nielsen AB, Yde J. An epidemiologic and traumatologic study of injuries in handball. Int J Sports Med 1988:9: 341-4.
Lin DY, Wei DJ. The robust inference for the Cox proportional hazards model. J Am Stat Assoc 1989;84: 1074-8.
Ebstrup JF, Bojsen-Moller F. Anterior cruciate ligament injury in indoor ball games. Scand J Med Sci Sports 2000;10: 114-6.
Olsen OE, Myklebust G, Engebretsen L, Bahr R. Injury mechanisms for anterior cruciate ligament injuries in team handball: a systematic video analysis. Am J Sports Med 2004;32: 1002-12.
Holm I, Fosdahl MA, Friis A, Risberg MA, Myklebust G, Steen H. Effect of neuromuscular training on proprioception, balance, muscle strength, and lower limb function in female team handball players. Clin J Sport Med 2004;14: 88-94.
Hewett TE, Stroupe AL, Nance TA, Noyes FR. Plyometric training in female athletes. Decreased impact forces and increased hamstring torques. Am J Sports Med 1996;24: 765-73.
Mjolsnes R, Arnason A, Osthagen T, Raastad T, Bahr R. A 10-week randomized trial comparing eccentric vs. concentric hamstring strength training in well-trained soccer players. Scand J Med Sci Sports 2004;14: 311-7.
Chappell JD, Yu B, Kirkendall DT, Garrett WE. A comparison of knee kinetics between male and female recreational athletes in stop-jump tasks. Am J Sports Med 2002;30: 261-7.
Fagenbaum R, Darling WG. Jump landing strategies in male and female college athletes and the implications of such strategies for anterior cruciate ligament injury. Am J Sports Med 2003;31: 233-40.(Odd-Egil Olsen, research fellow1, Grethe)