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Injury in elite New Zealand cricketers 2002–2008: descriptive epidemiology
  1. Warren Leonard Frost1,
  2. David John Chalmers2
  1. 1Rochester and Rutherford Hall, Christchurch, New Zealand
  2. 2Injury Prevention Research Unit, Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
  1. Correspondence to Warren Leonard Frost, Rochester and Rutherford Hall, 77 Ilam Road, Christchurch 8041, New Zealand; wmfrost{at}xtra.co.nz

Abstract

Objective To describe the incidence, prevalence, nature and severity of injury to elite New Zealand cricketers for the 2002/2003 to 2007/2008 seasons.

Design Prospective cohort.

Setting Elite cricket in New Zealand.

Participants 248 elite male cricketers.

Main outcome measures Incidence and prevalence rates.

Results The overall match injury incidence rate for the international competition (51.6 injuries per 10 000 player-hours; 95% CI 40.1 to 65.3) was almost twice that of the domestic competition (27.2; 23.5 to 31.4). The prevalence rate for the international competition (12%; 11.3% to 12.8%) was significantly higher than that for the domestic competition (9.7%; 9.4% to 10.1%). Overall, 79.5% of injuries occurred in matches and 48.7% of all injuries were sustained while bowling. The lower limb was the body region most commonly injured (43.5%), the most common specific diagnosis was hamstring strains/tears (11.1%) and the injuries contributing the highest proportion of match days lost were stress fractures to the low back (22%).

Conclusions The findings of this study support ongoing injury surveillance in New Zealand and other test cricket playing nations for the purpose of describing injury and monitoring the effect of interventions over time.

  • Cricket
  • Epidemiology
  • Injury Prevention
  • Sporting injuries
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Introduction

There is a paucity of information on the epidemiology of injuries in elite New Zealand cricket players. The single article located in the scientific literature reported an incidence proportion of 59% for a cohort of first-class bowlers.1 A number of reports have been published of studies of elite players in other cricketing nations: Australia,2–4 South Africa,5–12 England13 ,14 and the West Indies.15 Comparison between studies has been difficult due to inconsistent definitions and differing methods of data gathering and analysis being used.2 ,13 ,14 To address this problem, representatives of six test-playing nations collaborated in the development of a consensus statement on methods for injury surveillance in international cricket.16–19

The present research was initiated in 2002, with the objective of establishing an injury surveillance system for elite cricket in New Zealand that could be used to investigate injuries and their impact on the game. Surveillance is recognised as the first step in developing intervention strategies.20–22 The aim of this study was to describe the incidence, prevalence, nature and severity of injury to elite New Zealand cricketers for the 2002/2003 to 2007/2008 seasons, using data from the surveillance system.

Methods

A prospective cohort design was used for the surveillance system, with separate but not independent cohorts being enrolled in each of the six seasons. To allow international comparisons the definitions and methods prescribed in the consensus statement were adopted.16–19 The surveillance system was first implemented in the 2002–2003 season, prior to the consensus statement being published, but was designed in consultation with members of the group that developed the statement. Data collected before publication of the statement was reformatted to align it with the methods prescribed.

Prior to the beginning of each season each of six domestic first-class teams contracted players to be members of their ‘squad’.16–19 These players formed the cohort that was followed throughout the season. Any players joining a squad during the season were added to the cohort and followed for the remainder of the season. As players retired or missed selection for a subsequent season they were excluded from the cohort for that season. Players selected to represent New Zealand in the ‘international team’16–19 were drawn from the domestic first-class teams and could, therefore, be counted as domestic or as international players at different times during the course of a season.

Each player was classified according to his primary skill (this classification was made independently by a past director of the New Zealand Cricket Academy). A player's primary skill was the skill he was selected to perform during the season. The player types used are shown in table 1. A player was classified as an all-rounder if he was recognised as being able to perform more than one skill.

Table 1

Player types with primary skill definitions

For the purposes of this research, the New Zealand season was defined as the period from April 1 to March 31. Where a series of games began in March and ended in April it was counted as part of the season in which it began.16–19 International matches were all test matches, one-day matches and Twenty20 matches involving the international team.16–19 Domestic matches were all first-class matches, one-day matches and Twenty20 matches in which the six domestic teams played.16–19 The study included all matches played from 9 April 2002 through to 11 April 2008. The definitions for new injury, recurrent injury and recovery from injury were taken from the consensus statement.16–19 Injuries were classified using the Orchard sports injury classification system.23 ,24

Injuries were recorded in Excel spreadsheets by the team physiotherapists. Player participation in matches was recorded by the physiotherapists and checked against published season records.25–30

Analyses

All data were collated in a Microsoft Access database and all analyses were undertaken using the STATA statistical package.31 Incidence and prevalence rates were calculated using methods consistent with those prescribed in the consensus statement16–19 but adapted for use with STATA. The 95% CIs were calculated using the STATA CI procedure.31

In calculating ‘match injury incidence rates’ (injuries per 10 000 player-hours) the numerator was the number of new injuries occurring in matches (ie, excluding recurrent injuries) and the denominator was team match exposure time. Whereas the consensus statement prescribes a method for calculating exposure time for a team,16–19 the exposure time for each player was estimated individually and the estimates summed to produce the team match exposure time. Where a match was abandoned (without a ball being bowled) the match was classified as ‘washed out’ and no exposure time was recorded. In calculating ‘seasonal injury incidence rates’ (injuries per squad per season), the numerator was the number of training and match injuries (new, recurring and gradual onset) multiplied by ‘squad season’ (defined as 1500 player-days) and the denominator the total number of days played by a squad multiplied by the number of players in a squad minus the number of days washed out.16–19 In calculating the ‘injury prevalence rate’ (expressed as a percentage), the numerator was missed match days and the denominator the number of match days multiplied by squad members exposed.

Results

Two hundred and forty-eight players were followed. A total of 415 injuries were sustained by 152 players, resulting in 2651 lost match days (ie, the total number of days players were not available for selection because of injury or illness).

As shown in table 2, the match injury incidence rate for the international competition across all seasons and all match types (51.6 injuries per 10 000 player-hours; 95% CI 40.1 to 65.3) was observed to be almost twice that of the comparable rate for the domestic competition (27.2; 23.5 to 31.4). With the exception of the 2006–2007 season, however, in which the rate for the international competition (97; 59.3 to 149.9) was more than three times that of the domestic competition (30.6; 21.4 to 42.3), no significant differences were observed between international and domestic competitions by season. The only match type for which significant differences between international and domestic competitions were observed was one-day matches. The one-day match incidence rate for the international competition across all seasons (73.1; 53.3  to 97.9) was twice that of the comparable rate for the domestic competition (36.2; 27.3 to 47.1). Again, a significantly higher rate was observed for the international competition (111.4; 60.9 to 186.3) compared to the domestic competition (28.3; 11.4 to 58.3) in only the 2006–2007 season. The overall one-day match incidence rate for the international competition (73.1; 53.3 to 97.9) was more than twice that for test matches (30.1; 18.6 to 46) but no significant differences were observed for individual seasons. No differences were observed for the domestic competition. With the exception of the 2003–2004 season, the seasonal incidence rate was significantly higher for the international competition than for the domestic competition (table 3).

Table 2

Match injury incidence rates per 10000 player-hours (95% CI) by season and match type

Table 3

Seasonal injury incidence rates per squad per season (95% CI) by season

A total of 3864 match days was lost because of injury during the study period, giving a prevalence rate of 10.2% (95% CI 9.9% to 10.5%). The prevalence rate for the international competition across all seasons (12%; 11.3% to 12.8%) was observed to be significantly higher than that for the domestic competition (9.7%; 9.4% to 10.1%; table 4). Significantly higher prevalence rates were observed for the international competition compared to the domestic competition in four of the six seasons. Pace bowlers had the highest prevalence rate of all player types (18.7%; 18% to 19.3%). This rate was significantly higher than the rates for spin bowlers (5.5%; 4.8% to 6.3%), batters (5.4%; 5.1% to 5.8%) and wicket keepers (3.8%; 3.1% to 4.5%). A higher prevalence rate was observed for pace bowlers in the international competition (21.1%; 19.6% to 22.7%) compared to those in the domestic competition (18.1%; 17.4% to 18.8%). Batters in the international competition (9.3%; 8.4% to 10.3%), also, had a higher prevalence rate than batters in the domestic competition (4.4%; 4% to 4.7%). No significant difference was observed between spin bowlers in the international competition (4.7%; 3.5% to 6.2%) and those in the domestic competition (5.8%; 5% to 6.7%). Wicketkeepers in the domestic competition (4.6%; 3.8% to 5.6%) had a higher prevalence rate than those in the international competition (0.9%; 0.3% to 2%).

Table 4

Injury prevalence rates (%; 95% CI) by season

Table 5 reports the circumstances in which injury incidents occurred over the six seasons. Almost 80% of injuries occurred in matches and bowling was the commonest activity in which incidents occurred (48.7%).

Table 5

Circumstances of injury occurring in practices and matches

Injury incidents by body region and match days lost are shown in table 6. Overall, the lower limb was the most frequently injured body region (47.3%) and contributed the highest proportion of match days lost (43.5%), followed by the trunk/back (25.1%; 37.1%) and upper limb (17.8%; 14.9%). This result was consistent across competitions. Injury incidents by body part and match days lost are shown in table 7. The leading three body parts injured in the domestic competition were: thigh (16.3%), low back (15%) and abdomen (8.7%). The leading three incidents in the domestic competition by severity, as measured by percentage of match days lost, were: low back (28.3%), knee (11.2%) and thigh (10.8%). The leading three body parts injured in the international competition were: thigh (19.1%), illness (14.8%) and low back (12.2%). The leading three incidents in the international competition by severity were: low back (22.1%), knee (20.1%) and shoulder (10.9%).

Table 6

Injury incidents (%) by body region and match days lost

Table 7

Injury incidents (%) by body part and match days lost

Muscle tear/sprain was the most common mechanism of injury in the domestic (45%) and international (25%) competitions. The more common injuries by specific diagnosis are given in table 8. The severity of fractures to the lumbar region is clearly observed with fractures to pars interarticularis and vertebrae accounting for 5.5% of all incidents, but 22% of all missed match days. The commonest specific diagnosis was hamstring strain/tear 11.1%. Although systemic non-specific virus accounted for 6% of all incidents, the loss of match days was only 1.7%. This pattern of relatively low severity of injury was also observed with hamstring strain/tear, groin muscle strain and lumbar facet joint strain/jar.

Table 8

Common injury incidents (%) by specific diagnosis and match days missed

Discussion

The definitions and methods of data collection used were generally consistent with the consensus statement. One exception was the classification of player type. According to the consensus statement, to be classified as a bowler a player must have ‘averaged more than five overs bowled in matches during the previous two seasons’.16–19 This criterion was not applied as many players who are called upon to bowl for a limited number of overs, would have been incorrectly classified as bowlers when their primary skill was batting. Instead, players were classified by an expert, with the resulting classification exceeding the minimum requirements of the consensus statement. Another departure was the method of estimating exposure time, which was player-based rather than team-based as prescribed.16–19 The estimates were consistent with those that would have been obtained using the prescribed method.

The provision of CIs around the incidence and prevalence point estimates is not prescribed by the consensus statement but their inclusion added strength to this study. They provided a measure of the reliability of the estimates as well as allowing statistical comparisons to be made between competitions and between seasons. The provision of CIs is recommended for future studies using the consensus methods.

One shortcoming of this study was that the numbers of overs delivered by bowlers and faced by batters were not recorded electronically by New Zealand Cricket at the time of the study. It is understood that such a system is now in place.

The overall match injury incidence rate for the New Zealand international competition (51.6/10 000 player-hours) was slightly higher than the upper end of the range of rates reported for Australia's international competition (27.3–49.4) in the period 2002–20054 but much lower than that for South Africa in 2004–2006 (90).12 The incidence rate in test matches was higher than that for the West Indies in the 2003–2004 season (48.7).15 The overall match injury incidence rate for the New Zealand domestic competition (27.2 per 10 000 player-hours) was equal to the lower end of the range of rates reported for Australia's domestic competition (27.3–33)4 and less than that for South Africa in 2004–2006 (30).11

The overall match injury incidence rate for the international competition (51.6; 95% CI 40.1 to 65.3) was almost twice that for the domestic competition (27.2; 23.5 to 31.4). The primary influence on the overall rate appears to have been the rates for the one-day matches, with the rate for the international one-day competition being twice that of the domestic one-day competition (73.1; 53.3 to 97.9 vs 36.2; 27.3 to 47.1). Similar patterns are apparent in the international and domestic incidence rates reported by Australia, South Africa and the West Indies.3 ,4 ,11 ,12 ,15 This phenomenon may be due to the total amount of cricket played by international cricketers compared to domestic players and a cumulative effect of the injuries sustained by the former.32

The overall one-day match incidence rate for the international competition (73.1; 53.3 to 97.9) was more than twice that for test matches (30.1; 18.6 to 46). Australia reported a similar finding (57.7–72.2 vs 8.8–44.6).4 No difference was observed between one-day and first-class matches for the domestic competition. Australia (37.2–67 vs 23–24.5) and the West Indies (25.4 vs 13.9), however, reported higher incidence rates in one-day matches than in first-class matches.4 ,15 Interestingly, for both South Africa and the West Indies the one-day international incidence rate was lower than that for test matches (40.6 vs 48.7 and 79 vs 95).12 ,15 It will be of interest to observe the development of Twenty20 cricket to determine if there is a higher incidence of injury in this version of the game which has an even shorter duration than the one-day game. Early indications are that this may be so,33 but the CIs for the estimates obtained were very wide because of the low number of Twenty20 matches played in the seasons observed.

The injury prevalence rates for the domestic competition were relatively stable across the six seasons, compared to the rates for the international competition which fluctuated across seasons. A significantly higher injury prevalence rate was observed for the international competition (12%; 11.3% to 12.8%), compared to the domestic competition (9.7%; 9.4% to 10.1%). This higher rate may be because the international season is longer than the domestic season, with some injuries sustained in the previous season still having an impact in the following season. In contrast, South Africa reported a higher prevalence rate for provincial players (8%) than for international players (3.8%).11 ,12 The Australian and West Indian studies do not report overall prevalence rates for their international and domestic competitions but reported seasonal rates are lower than New Zealand rates. Australia averaged 9.4% for their international one-day competition, 7.5% for test matches, 8.5% for their domestic one-day competition and 8.2% for their first-class competition.

Overall, 79.5% of injuries occurred in matches and 48.7% of all injuries were sustained while bowling. Bowling has long been identified as the aspect of cricket with the highest risk of injury.1–15 Overall, pace bowlers had the highest injury prevalence rate (18.7%; 18% to 19.3) and the prevalence rate for pace bowlers in the international competition (21.1%; 19.6% to 22.7%) was higher than the rate for those in the domestic competition (18.1%; 17.4% to 18.8%). Pace bowlers were also reported to have the highest rates (14%, 14.14%) in the two Australian studies3 ,4 and the West Indian study reported that fast bowlers contributed a high proportion of time lost due to injury (20%).15

Orchard3 has suggested that dissuading teams from playing football in warm-ups would reduce injuries. Warm-up injuries in the present study accounted for only 4.6% of all injuries (practice and match), while fielding drills in training accounted for 3.4%. Overall, injuries at practice accounted for 20.5% of all injuries. Consistent with Orchard, it is considered that where training conditions can be controlled, opportunities should be explored to reduce the incidence of training injuries through drill design and player management.

The finding that the body part most commonly injured was the thigh (domestic: 16.3%, international: 19.1%) is consistent with findings reported by Orchard et al who found the seasonal incidence rate by body area was greatest for groin/buttock/thigh.4 ,32 Further analysis of these cases indicated that muscle strain/tear was the commonest mechanism of injury. The injured body part contributing the highest proportion of match days missed was the low back (domestic: 28.3%, international: 22.1%). Lumbar stress fractures have long been recognised as the most severe bowling injury in cricket.2–10 These findings confirm that this is also the case in elite cricket in New Zealand.

Meaning of the study

Ongoing injury surveillance is considered fundamental to sports injury prevention to: (1) describe injury problems and (2) to monitor the effects of interventions over time.14 ,16–20 ,34 This study has described the incidence, prevalence, nature and severity of injury to elite New Zealand cricketers, using data collected by a surveillance system implemented over six seasons. Conformity of the system with internationally agreed surveillance methods16–19 enabled comparison with findings reported for three other test-playing nations.4 ,12 ,15 To achieve the second role of injury surveillance (monitoring injury over time), it is important that implementation of the New Zealand cricket surveillance system continues. If the ambition of publishing an ‘annual ‘world’ elite cricket injury surveillance report’ envisaged by Orchard et al4 is to be realised then reports, such as this, from more test-playing nations will be needed. It is agreed that the International Cricket Council support may be needed to fund the development and ongoing implementation of surveillance systems, especially in less established cricketing nations.

Unanswered questions and future study

Having described the injury problem in elite New Zealand cricket the next steps in preventing injury are: (1) to identify risk factors and mechanisms for injury in key areas identified by the present report, such as the high incidence of injury in pace bowlers and the high impact of low-back injury, and (2) to adopt or develop interventions designed to address these problems. Some research has already been undertaken elsewhere in relation to the high incidence of injury in pace bowlers,4 ,35–37 while new research may be required to identify risk factors (and ultimately interventions) for low-back injury. Such research is usually not undertaken in the context of injury surveillance but, fortuitously, the cohort design prescribed by the consensus statement16–19 and adopted for the New Zealand cricket injury surveillance system lends itself to the investigation of risk factors.34 Orchard et al have already demonstrated the utility of this design in identifying risk factors for bowling injury.3 ,32 ,38 If bowling and batting exposure data were added to the New Zealand surveillance system then the potential would exist to investigate risk factors for bowling in elite New Zealand cricketers.

What this study adds

  • This is the fourth study to report results obtained using the consensus statement on methods for injury surveillance in international cricket.

  • Evidence was found of significantly higher incidence and prevalence rates for the international competition compared to the domestic competition.

  • It was found that stress fractures to the low back contributed the highest proportion of match days lost.

Acknowledgments

The authors wish to thank the following people who contributed to this study: Dr John Orchard for his extensive encouragement and assistance in setting up this surveillance system; physiotherapists Pip Sail, Shane Derry, John Hayward, Colin Tutchen, Rob Cashman, Brett Warman, Richie Marsden, Ash Stiven, Duncan Drew and Dayle Shackel for recording the injury data; Ari Samaranayaka, Gabrielle Davie and Melanie Bell for statistical advice and support; Professor Roger Bartlett for his cosupervision of the first author's masters thesis; Mr Dayle Hadlee for contributing unlimited time and assistance in categorising players; and New Zealand Cricket and the New Zealand Cricket Players Association for supporting this research. Finally, our indebted thanks go to all those domestic and international cricketers who permitted the collection of the data used in this study and showed interest in better understanding injuries in New Zealand cricket.

References

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Footnotes

  • Contributors WLF was the principal investigator, contributed to the design, was responsible for data collection and analysis, and led the writing of the paper. DJC contributed to the design and writing of the paper. WLF is the guarantor.

  • Funding The funding for this study was provided by New Zealand Cricket.

  • Competing interests All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare that (1) WLF was an employee of Cricket New Zealand when this study was conducted and (2) DJC is a retired employee of the University of Otago; and have no financial relationships with commercial entities that might have an interest in the submitted work. All authors also declare that they have (3) no spouses, partners or children with relationships with commercial entities that might have an interest in the submitted work; and (4) no non-financial interests that may be relevant to the submitted work.

  • Ethics approval New Zealand Ministry of Health, Multi-region Ethics Committee (Ref: MEC/07/57/EXP).

  • Provenance and peer review Not commissioned; externally peer reviewed.

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