Match scheduling plays an important role in player workload and consequently, injury risk. This blog is based on a study by Dr John Orchard, Dr Alex Kountouris and Dr Kevin Sims of Cricket Australia on workload variations and other schedule-related factors in terms of injury incidence.
Introduction
Injury is a common challenge facing all sports, with much attention being directed to the role of workload. Spikes in workload have been associated with increased injury in sports such as football (soccer), rugby league, Australian football and rugby union. Additionally, chronic load has been associated with reduced injury in rugby league, whilst a congested match schedule (reduced time between games) has been associated with increased, or no different, injury in football (soccer).
In cricket, spikes in workload have been associated with injury, however medium and longer-term workloads have also been implicated. An additional challenge is that cricket is played in three different formats: T20 (one 20-over innings per side), one-day (one one-day innings per side) and multi-day (two unlimited innings played over 4-5 days). Each match format has unique workload demands related to intensity and duration.
At international level, one-day cricket matches are generally scheduled in one of two ways as follows. In a regular international program, two (sometimes three) teams will contest a series (usually 3-7) of one-day matches surrounded by multi-day and/or T20 matches. The transition between the different formats typically results in workload variability (either an upgrade in workload from preceding T20 matches or a downgrade from preceding multi-day matches). Every two years, the International Cricket Council (ICC) holds one of its two major one-day tournaments (Cricket World Cup, Champions Trophy). These tournaments are unique in cricket because they involve all major cricket playing nations (8-12 teams) and have a high number of consecutive one-day matches. Other match formats are not played during the tournament and due to the importance of the tournament, teams typically play one-day matches in preparation leading into the tournament. The large number of consecutive matches of the same format results in less workload variability.
At the highest domestic level in Australia, the season schedule has changed from a non-tournament structure to a one-day tournament structure. Up to and including season 2012-13, one-day matches were played across a 6-month domestic season (10 home and away rounds) typically two days after a multi-day game between two state teams (Figure 1(a)). This typically resulted in alternating high and lower workload games throughout the season, somewhat similar to the regular international format. In 2013-14, the schedule was changed to an early-season one-day tournament where the state teams play each other in one-day cricket over a period of one month (Figure 1(b)). This new structure mimics the international tournaments.
The purpose of this study was to investigate the relative injury incidence between non-tournament and tournament match schedules for elite Australian cricketers participating in domestic or international competitions.
Materials and Methods
Match and de-identified injury data were obtained from the Cricket Australia database and handled in accordance with National Health and Medical Research Council (NHMRC) guidelines for research.
Domestic one-day competitions over 6-seasons were classified as non-tournament structure (3 seasons, 2010-11 to 2012-13) or tournament structure (3 seasons, 2013-14 to 2015-16). International one-day competitions over 21 years were classified as non-tournament structure (regular structure of one-day matches surrounded by other formats) or tournament structure (one-day World Cup or Champions Trophy tournaments).
Cricket injuries (or ‘relevant’ injury for surveillance purposes) were defined as any injury or other medical condition that either: 1) prevents a player from being fully available for selection in a major match; or 2) during a major match, causes a player to be unable to bat, bowl or keep wicket when required by either the rules or the team’s captain.
Injury incidence in this study refers to match injury incidence (only taking into account match onset injuries, as opposed to training injuries and gradual/insidious onset injuries). The unit used is injuries per 1000 team days of play.
Injury prevalence figures will also be presented as a second indicator of injury rates. Injury prevalence considers the average number of squad members not available for selection through injury for each match divided by the total number of squad members. Injury prevalence is expressed as a percentage, representing the percentage of players missing through injury on average.
Injury incidence between non-tournament and tournament structures were compared using odds ratios with 95% confidence intervals (CI). Significance was set a priori as p<0.05 and where the 95% CI range does not include 1.0.
Domestic T20 and multi-day injury statistics are included for comparison. The number of matches in each format are detailed in Table 1.
Results and Discussion
At domestic level, injury incidence for one-day matches averaged 321 per 1000 days of play during the three seasons of non-tournament scheduling, compared to an average of 200 per 1000 days of play during the three seasons of tournament scheduling (Table 2). Injury prevalence averaged 16.7% and 10.1% respectively (Table 3). The odds ratio for tournament scheduling was 0.62 (95% CI 0.37-1.05), hence not significant. Similarly, the odds ratio for injury during multi-day competition was 0.76 (0.55-1.05). There was no change in the injury incidence for T20 competitions (played as a tournament across all years).
At international level, injury incidence was lower for tournament schedules (150 per 1000 days of play) compared to non-tournament schedules (284 per 1000 days of play) (OR 0.53 (0.28-1.00)) (Table 4). When domestic and international data were combined, injury incidence was significantly lower for tournament schedules (181 per 1000 days of play) compared to non-tournament schedules (293 per 1000 days of play) (OR 0.62 (0.48-0.79)) (Table 5).
The international tournament injury rates are comparable to those reported for multiple teams at the Cricket World Cup in 2011. Although injury definitions differ, injury incidence was 221 per 1000 days of play (20.1 match injuries per 1000 player days x 11 players) and injury prevalence was 5%.
The results of this study suggest that one-day matches scheduled as a tournament are associated with lower injury incidence and prevalence than when interspersed with T20 and multi-day matches. The question which follows is whether this finding can be attributed to less variable workloads with a tournament structure. We acknowledge that this question cannot be answered with this higher-level analysis as there are several confounding factors to consider as discussed below.
Firstly, team match loads do not translate to individual workloads. Individuals have different batting, bowling, fielding and wicket keeping demands depending on their role within the team and how the match unfolds. Selection or non-selection and individualised training loads also contribute to individual workload variability.
In addition to workload variability, the match schedule also influences player fatigue and recovery which may have also played a role in the injury rates observed. Tournament scheduling typically includes longer (as many as seven days) breaks between games, whereas non-tournament scheduling typically includes 2-4 day breaks between games. Therefore, it is possible that the lower injury incidence observed during tournaments may be partially attributed to more opportunity for recovery. Interestingly, this notion is not supported by a previous study from a similar cohort which did not observe an increase in injury incidence with a compressed multi-day schedule.
Prior workload is another factor which is likely to influence injury incidence during one-day matches. For instance, prior to the domestic one-day tournaments in 2013-14 and 2014-15, two of the six teams competed in a T20 tournament. This was not the case for 2015-16 when less injuries were observed. It is possible that workload variation from the T20 to one-day tournament was a factor, similarly, fatigue from the previous tournament may have been carried into the one-day tournament, however further research is needed.
Finally, home and away scheduling is also a factor in player fatigue and exposure to certain playing conditions. Previous analysis has shown that one-day matches played in Australia have higher injury rates than away one-day matches played overseas. This could be due to a combination of factors, including larger size grounds in Australia, greater numbers of balls bowled by higher-risk pace bowlers in Australia (as opposed to spin bowlers elsewhere), greater number of non-tournament matches in Australia, or other factors such as the stage of the season that home versus away matches are typically scheduled. These factors may have influenced the international findings in the current study, as non-tournament matches are more often played in Australia and tournaments are more often played outside Australia.
Conclusions
This study of elite Australian cricketers participating in international and domestic one-day competitions over many years provides valuable insight into the influence match scheduling may have on injury rates. Lower injury rates were observed during one-day matches scheduled as a tournament format compared to one-day matches interspersed with T20 and multi-day matches. This finding is consistent with the theory that low workload variations reduce the risk of injury, however, several other schedule-related factors may be intertwined. Practical implications pertain to player preparation and selection to counter the increased risk associated with non-tournament one-day schedules.
References available on request
Authors
Dr John Orchard is a sport and exercise physician with over 25 years’ experience. He has been published in over 300 scientific publications. John has been involved with many elite sports teams including the Sydney Swans, Sydney Roosters, Australian cricket team and the Australian NSW State of Origin Team. He is currently the Chief Medical Officer for Cricket Australia.
Dr Alex Kountouris is currently the Sports Science and Sports Medicine Manager at Cricket Australia, as well as the lead physiotherapist for the Australian men’s cricket team. Prior to his appointment with Cricket Australia, Alex was the lead physiotherapist for the Sri Lankan men’s cricket team. His research interests include sports injuries, injury prevention and rehabilitation.
Dr Kevin Sims is currently the lead physiotherapist and Case and Rehabilitation Manager at Cricket Australia. He is also a casual academic at the University of Queensland where he teaches on the Masters program. His research interests include lumbar bone stress injury, hip pathology and injury prevention.