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Assessment of player performance following return to sport after hamstring muscle strain injury
Journal of Science and Medicine in Sport (2006) 9, 87—90
ORIGINAL PAPER
Assessment of player performance following return to sport after hamstring muscle strain injury G.M. Verrall a, Y. Kalairajah a,∗, J.P. Slavotinek b, A.J. Spriggins a a b
SPORTSMED SA Sports Medicine Clinic, 32 Payneham Road, Stepney, Adelaide, SA 5069, Australia Department of Medical Imaging, Flinders Medical Centre, Adelaide, Australia KEYWORDS Hamstring muscle strain; Player performance; Return to sport
Summary Objective: To determine if there is any decrease in playing performance of athletes following return to sport after recovery from hamstring muscle strain injury. Design: Prospective cohort study. Participants: One professional Australian football team over two playing seasons. Methods: For every game, the team coach rated player performance proportional to time spent on the ground playing (an integer score out of a maximum of 10). Player performance ratings were compared pre- and post-hamstring muscle strain injury to assess player performance upon return to sport. Results: Thirteen athletes had hamstring injuries and the required player ratings were available. The mean player performance rating for the entire playing season in which the player was injured was 6.9. The mean player performance rating for the two games prior to injury was 6.8 as opposed to 5.4 for the two games after return to sport. Athletes had a significantly lower player performance rating immediately upon return to sport when compared to ratings for the entire season (p < 0.001) and when compared to ratings from the two games prior to injury (p < 0.001). Conclusions: Following return to sport from hamstring injury, player performance as assessed by the team coach is reduced. This suggests that some athletes may return to sport prior to complete resolution of the injury. © 2006 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
Introduction Hamstring muscle strain injuries are common in many sports, including the various football codes.1,2 In Australian football, hamstring injuries ∗
Corresponding author. Tel.: +61 8 8362 8111; fax: +61 8 8362 6635. E-mail address: [email protected] (Y. Kalairajah).
are responsible for the greatest quantity of competition time lost due to injury2 and have a high recurrence rate.2,3 Athletes in professional sports are aware of the troublesome nature and high recurrence rate of hamstring injuries.4 Despite this there is often an expectation from the team, coach and the athletes themselves to return to active competition as soon as practical following this injury. Although no data have
1440-2440/$ — see front matter © 2006 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.jsams.2006.03.007
88 Table 1
G.M. Verrall et al. Summary of player performance ratings in injured players
For entire season For two games prior to injury For two games after return to sport
Mean
Median
Range
S.D.
6.8 6.8 5.1
6.7 7.0 5.0
5.7—7.8 5.5—8.0 4.0—6.5
0.56 0.70 0.87
Data is presented for the 13 players where comparisons could be made. Comparing all three columns a Friedman test demonstrated significant difference between the three periods p < 0.001. A pairwise Exact Wilcoxon Signed Ranks Test demonstrated significant differences between player ratings for the entire season compared to player ratings for the two games after return to sport p < 0.001 and player ratings for the two games prior to injury compared to player ratings for the two games after return to sport p < 0.001.
been presented about player performance after return to sport from hamstring injury, evidence from magnetic resonance imaging (MRI) studies,5 laboratory studies of muscle stretch injury6,7 and the observed high recurrence rate3 suggests that the injury in many cases has not fully resolved at the time of return to sport. Accordingly, the aim of this study was to determine if athlete performance is poorer following return to sport after recovery from hamstring injury.
Method All athletes were male and played professional Australian football for an elite level team consisting of first and reserve grade teams. The study was conducted over two full playing seasons with the team playing weekly for 25 competition matches in each season. Hamstring muscle strain injury was noted when a player developed pain localised to the posterior thigh during the course of playing or training and subsequent MRI scan detected focal intramuscular hyperintensity within the hamstring muscle(s) on T2 images.8—10 For every first grade game the club coach rated player performance proportional to time spent on the ground. Players who had limited on-field time (less than one-quarter) were not rated. This rating was an integer score to a maximum of 10. Player ratings for the two games prior to injury and for the entire playing season in which the player was injured were compared to player ratings for the first two games played after return to sport. Players were included in the study if they played at least two matches out of a possible two in the first grade team after return to sport following injury. An exact Friedman test was performed comparing all data followed by pairwise Exact Wilcoxon Signed Rank Tests if the Friedman test was significant. Thus, we compared player performance rat-
ings from the two matches after returning to competition to the player performance ratings of the player for the entire season and to the player performance ratings for the player in the two matches prior to injury.
Results Across the two seasons, a total of 20 hamstring injuries were recorded. Thirteen of these injuries had relevant player ratings and were therefore included in the analyses. Seven athletes were excluded (three had insufficient pre-injury ratings, four had insufficient post-injury ratings). Three of the 13 returned to play in the reserve grade and played one match there, before being promoted to the first grade team, whereas the other 10 played in the first grade team for their return from injury match. Only first grade matches were rated. Player ratings are summarised in Table 1. There was significantly reduced performance in the first two games after return to sport compared to performance during the entire season (p < 0.001) and the two games prior to the injury (p < 0.001).
Discussion This study demonstrates that player performance in Australian football is reduced in the immediate return to play period following hamstring injury. This is consistent with the hypothesis that athletes often return to sport prior to complete resolution, with respect to muscle healing, of injury.3 As obtaining direct histological evidence is difficult in the study of athletic hamstring injuries, indirect evidence, such as player performance or persistent MRI abnormalities may provide support for the proposition of incomplete resolution of injury prior to return to sport. Other studies also support this proposition.
Player performance after hamstring muscle strain injury It has been demonstrated that at six weeks posthamstring injury 36% of athletes still had signal intensity changes on MRI, despite nearly all of these athletes having returned to competition sport by this time.5 Laboratory studies that analyse muscle stretch injury and subsequent healing6,7 also suggest that the injury may take many weeks to heal, longer than the average 28-day2 hamstring injury convalescent interval. Finally, it has been shown that there is an increased susceptibility for re-injury that lasts up to eight weeks after return to sport.3 How incomplete resolution of injury impacts negatively upon player performance upon return to sport is not clear. It is possible that the hamstring muscle has reduced capacity to perform following rehabilitation and that this would be important in a sport, such as Australian football, that requires a large amount of high-intensity interval running. Other factors that could be responsible include a decreased level of fitness of the players upon return to sport because of their time out of match-playing, reduction in confidence that may result in the athlete not ‘‘risking’’ their hamstring as players are aware of the high re-injury rate, reduced skill level because of significant absence from match-playing, and finally a perceived negative assessment (bias) of performance by the coach as he may place the player under more rigorous assessment than would normally be the case. When considering the impact that decreased performance of a player may have on team performance, it may be reasonable to suggest that players should have a longer convalescence interval before returning to sport following hamstring injury. It is not clear whether or not a longer convalescent interval would improve player performance upon returning to sport. With the recurrence rate in the first week upon returning to sport in Australian football being relatively low (13%)3 , by justifying the timing of return to sport, there may be longterm benefit to the team for the player returning from injury gaining match conditioning that may allow improved performance in subsequent matches. When interpreting the findings of this study it is important to consider its inherent weaknesses. The most obvious weakness of this study is the limited size of the injured group. Another weakness was the failure to look at return to sport performance following other injuries as these athletes may demonstrate a similar trend. Furthermore, the validity and reliability of the player performance ratings could not be assessed. Finally, direct comparisons from the literature are also not possible
89
as to our knowledge no study has looked at player performance criteria after return from any injury in any sport.
Conclusions This study demonstrates that player performance as assessed by the team coach is reduced following return to play after hamstring injury. This is consistent with the proposition from other studies that some athletes may return to sport prior to complete resolution of injury.
Practical implications • Player performance is reduced following return to play after hamstring injury. • Some athletes return to play prior to complete resolution of the hamstring injury. • Coaches, players and the medical team should be aware for the potential for player performance to be impaired when making decisions on the timing of return to play for hamstring injured athletes.
Acknowledgements The authors wish to thank Dr. Adrian Esterman for his statistical analysis. The coach of the Norwood football club, Mr. Peter Rhode is also thanked.
References 1. Arnason A, Sigurdsson SB, Gudmundsson A, et al. Risk factors for injuries in football. Am J Sports Med 2004;32(1S):5S—16S. 2. Orchard J, Seward H. Epidemiology of injuries in the Australian Football League, seasons 1997—2000. Br J Sports Med 2002;36(1):39—45. 3. Orchard J, Best TM. The management of muscle strain injuries: an early return versus the risk of recurrence. Clin J Sports Med 2002;12(1):3—5. 4. Garrett WE. Muscle strain injuries. Am J Sports Med 1996;24(6):S2—8. 5. Connell DA, Schneider-Kolsky ME, Hoving JL, et al. Longitudinal study comparing sonographic and MRI assessment of acute and healing hamstring injuries. Am J Roentgenol 2004;183(4):975—84. 6. Kaariainen M, Kaariainen J, Jarvinen TL, et al. Correlation between biomechanical and structural changes during the regeneration of skeletal muscle after laceration injury. J Ortho Res 1998;16:197—206. 7. Taylor DC, Dalton JD, Seaber AV, et al. Experimental muscle strain injury. Early functional and structural deficits and
90 the increased risk for reinjury. Am J Sports Med 1993;21: 190—4. 8. DeSmet AA, Best TM. MR imaging of the distribution and location of acute hamstring injuries in athletes. Am J Roentgenol 2000;174(2):393—9. 9. Slavotinek JP, Verrall GM, Fon GT. Hamstring injury in athletes: the association between MR measurements of the
G.M. Verrall et al. extent of muscle injury and the amount of time lost from competition. Am J Roentgenol 2002;179:1621—8. 10. Verrall GM, Slavotinek JP, Barnes PG, et al. Diagnostic and prognostic value of clinical findings in 83 athletes with posterior thigh injury. Comparison of clinical findings with magnetic resonance imaging documentation of hamstring muscle strain. Am J Sports Med 2003;31(6):969—73.
ORIGINAL PAPER
Assessment of player performance following return to sport after hamstring muscle strain injury G.M. Verrall a, Y. Kalairajah a,∗, J.P. Slavotinek b, A.J. Spriggins a a b
SPORTSMED SA Sports Medicine Clinic, 32 Payneham Road, Stepney, Adelaide, SA 5069, Australia Department of Medical Imaging, Flinders Medical Centre, Adelaide, Australia KEYWORDS Hamstring muscle strain; Player performance; Return to sport
Summary Objective: To determine if there is any decrease in playing performance of athletes following return to sport after recovery from hamstring muscle strain injury. Design: Prospective cohort study. Participants: One professional Australian football team over two playing seasons. Methods: For every game, the team coach rated player performance proportional to time spent on the ground playing (an integer score out of a maximum of 10). Player performance ratings were compared pre- and post-hamstring muscle strain injury to assess player performance upon return to sport. Results: Thirteen athletes had hamstring injuries and the required player ratings were available. The mean player performance rating for the entire playing season in which the player was injured was 6.9. The mean player performance rating for the two games prior to injury was 6.8 as opposed to 5.4 for the two games after return to sport. Athletes had a significantly lower player performance rating immediately upon return to sport when compared to ratings for the entire season (p < 0.001) and when compared to ratings from the two games prior to injury (p < 0.001). Conclusions: Following return to sport from hamstring injury, player performance as assessed by the team coach is reduced. This suggests that some athletes may return to sport prior to complete resolution of the injury. © 2006 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
Introduction Hamstring muscle strain injuries are common in many sports, including the various football codes.1,2 In Australian football, hamstring injuries ∗
Corresponding author. Tel.: +61 8 8362 8111; fax: +61 8 8362 6635. E-mail address: [email protected] (Y. Kalairajah).
are responsible for the greatest quantity of competition time lost due to injury2 and have a high recurrence rate.2,3 Athletes in professional sports are aware of the troublesome nature and high recurrence rate of hamstring injuries.4 Despite this there is often an expectation from the team, coach and the athletes themselves to return to active competition as soon as practical following this injury. Although no data have
1440-2440/$ — see front matter © 2006 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.jsams.2006.03.007
88 Table 1
G.M. Verrall et al. Summary of player performance ratings in injured players
For entire season For two games prior to injury For two games after return to sport
Mean
Median
Range
S.D.
6.8 6.8 5.1
6.7 7.0 5.0
5.7—7.8 5.5—8.0 4.0—6.5
0.56 0.70 0.87
Data is presented for the 13 players where comparisons could be made. Comparing all three columns a Friedman test demonstrated significant difference between the three periods p < 0.001. A pairwise Exact Wilcoxon Signed Ranks Test demonstrated significant differences between player ratings for the entire season compared to player ratings for the two games after return to sport p < 0.001 and player ratings for the two games prior to injury compared to player ratings for the two games after return to sport p < 0.001.
been presented about player performance after return to sport from hamstring injury, evidence from magnetic resonance imaging (MRI) studies,5 laboratory studies of muscle stretch injury6,7 and the observed high recurrence rate3 suggests that the injury in many cases has not fully resolved at the time of return to sport. Accordingly, the aim of this study was to determine if athlete performance is poorer following return to sport after recovery from hamstring injury.
Method All athletes were male and played professional Australian football for an elite level team consisting of first and reserve grade teams. The study was conducted over two full playing seasons with the team playing weekly for 25 competition matches in each season. Hamstring muscle strain injury was noted when a player developed pain localised to the posterior thigh during the course of playing or training and subsequent MRI scan detected focal intramuscular hyperintensity within the hamstring muscle(s) on T2 images.8—10 For every first grade game the club coach rated player performance proportional to time spent on the ground. Players who had limited on-field time (less than one-quarter) were not rated. This rating was an integer score to a maximum of 10. Player ratings for the two games prior to injury and for the entire playing season in which the player was injured were compared to player ratings for the first two games played after return to sport. Players were included in the study if they played at least two matches out of a possible two in the first grade team after return to sport following injury. An exact Friedman test was performed comparing all data followed by pairwise Exact Wilcoxon Signed Rank Tests if the Friedman test was significant. Thus, we compared player performance rat-
ings from the two matches after returning to competition to the player performance ratings of the player for the entire season and to the player performance ratings for the player in the two matches prior to injury.
Results Across the two seasons, a total of 20 hamstring injuries were recorded. Thirteen of these injuries had relevant player ratings and were therefore included in the analyses. Seven athletes were excluded (three had insufficient pre-injury ratings, four had insufficient post-injury ratings). Three of the 13 returned to play in the reserve grade and played one match there, before being promoted to the first grade team, whereas the other 10 played in the first grade team for their return from injury match. Only first grade matches were rated. Player ratings are summarised in Table 1. There was significantly reduced performance in the first two games after return to sport compared to performance during the entire season (p < 0.001) and the two games prior to the injury (p < 0.001).
Discussion This study demonstrates that player performance in Australian football is reduced in the immediate return to play period following hamstring injury. This is consistent with the hypothesis that athletes often return to sport prior to complete resolution, with respect to muscle healing, of injury.3 As obtaining direct histological evidence is difficult in the study of athletic hamstring injuries, indirect evidence, such as player performance or persistent MRI abnormalities may provide support for the proposition of incomplete resolution of injury prior to return to sport. Other studies also support this proposition.
Player performance after hamstring muscle strain injury It has been demonstrated that at six weeks posthamstring injury 36% of athletes still had signal intensity changes on MRI, despite nearly all of these athletes having returned to competition sport by this time.5 Laboratory studies that analyse muscle stretch injury and subsequent healing6,7 also suggest that the injury may take many weeks to heal, longer than the average 28-day2 hamstring injury convalescent interval. Finally, it has been shown that there is an increased susceptibility for re-injury that lasts up to eight weeks after return to sport.3 How incomplete resolution of injury impacts negatively upon player performance upon return to sport is not clear. It is possible that the hamstring muscle has reduced capacity to perform following rehabilitation and that this would be important in a sport, such as Australian football, that requires a large amount of high-intensity interval running. Other factors that could be responsible include a decreased level of fitness of the players upon return to sport because of their time out of match-playing, reduction in confidence that may result in the athlete not ‘‘risking’’ their hamstring as players are aware of the high re-injury rate, reduced skill level because of significant absence from match-playing, and finally a perceived negative assessment (bias) of performance by the coach as he may place the player under more rigorous assessment than would normally be the case. When considering the impact that decreased performance of a player may have on team performance, it may be reasonable to suggest that players should have a longer convalescence interval before returning to sport following hamstring injury. It is not clear whether or not a longer convalescent interval would improve player performance upon returning to sport. With the recurrence rate in the first week upon returning to sport in Australian football being relatively low (13%)3 , by justifying the timing of return to sport, there may be longterm benefit to the team for the player returning from injury gaining match conditioning that may allow improved performance in subsequent matches. When interpreting the findings of this study it is important to consider its inherent weaknesses. The most obvious weakness of this study is the limited size of the injured group. Another weakness was the failure to look at return to sport performance following other injuries as these athletes may demonstrate a similar trend. Furthermore, the validity and reliability of the player performance ratings could not be assessed. Finally, direct comparisons from the literature are also not possible
89
as to our knowledge no study has looked at player performance criteria after return from any injury in any sport.
Conclusions This study demonstrates that player performance as assessed by the team coach is reduced following return to play after hamstring injury. This is consistent with the proposition from other studies that some athletes may return to sport prior to complete resolution of injury.
Practical implications • Player performance is reduced following return to play after hamstring injury. • Some athletes return to play prior to complete resolution of the hamstring injury. • Coaches, players and the medical team should be aware for the potential for player performance to be impaired when making decisions on the timing of return to play for hamstring injured athletes.
Acknowledgements The authors wish to thank Dr. Adrian Esterman for his statistical analysis. The coach of the Norwood football club, Mr. Peter Rhode is also thanked.
References 1. Arnason A, Sigurdsson SB, Gudmundsson A, et al. Risk factors for injuries in football. Am J Sports Med 2004;32(1S):5S—16S. 2. Orchard J, Seward H. Epidemiology of injuries in the Australian Football League, seasons 1997—2000. Br J Sports Med 2002;36(1):39—45. 3. Orchard J, Best TM. The management of muscle strain injuries: an early return versus the risk of recurrence. Clin J Sports Med 2002;12(1):3—5. 4. Garrett WE. Muscle strain injuries. Am J Sports Med 1996;24(6):S2—8. 5. Connell DA, Schneider-Kolsky ME, Hoving JL, et al. Longitudinal study comparing sonographic and MRI assessment of acute and healing hamstring injuries. Am J Roentgenol 2004;183(4):975—84. 6. Kaariainen M, Kaariainen J, Jarvinen TL, et al. Correlation between biomechanical and structural changes during the regeneration of skeletal muscle after laceration injury. J Ortho Res 1998;16:197—206. 7. Taylor DC, Dalton JD, Seaber AV, et al. Experimental muscle strain injury. Early functional and structural deficits and
90 the increased risk for reinjury. Am J Sports Med 1993;21: 190—4. 8. DeSmet AA, Best TM. MR imaging of the distribution and location of acute hamstring injuries in athletes. Am J Roentgenol 2000;174(2):393—9. 9. Slavotinek JP, Verrall GM, Fon GT. Hamstring injury in athletes: the association between MR measurements of the
G.M. Verrall et al. extent of muscle injury and the amount of time lost from competition. Am J Roentgenol 2002;179:1621—8. 10. Verrall GM, Slavotinek JP, Barnes PG, et al. Diagnostic and prognostic value of clinical findings in 83 athletes with posterior thigh injury. Comparison of clinical findings with magnetic resonance imaging documentation of hamstring muscle strain. Am J Sports Med 2003;31(6):969—73.