Original researchRelationship between training load and injury in professional rugby league players
Introduction
Rugby league is an international collision sport played at both junior and senior levels.1 A typical rugby league match requires players to compete in a challenging contest, comprising intense bouts of sprinting and tackling, separated by short bouts of lower intensity activity. During the course of a rugby league match, each team will perform an average of 300 tackles; forwards are exposed to an average of 55 physical collisions (39 tackles, 16 hit-ups), while backs are exposed to an average of 29 physical collisions (16 tackles, 13 hit-ups).2 As a result, rugby league players are required to have well developed physiological and anthropometric qualities, combined with a wide range of offensive and defensive skills.
Several studies have documented the relationship between training loads and injury rates in sub-elite rugby league players.3, 4, 5, 6 In the first study to investigate the influence of training load on injury rates, Gabbett3 reported a significant correlation (r = 0.86) between training load and injury, suggesting that the harder rugby league players train, the more injuries they will sustain. In a subsequent study of sub-elite players it was shown that reductions in training load resulted in marked reductions in injury rates, without compromising training-induced improvements in physical qualities.4 Similar findings have been observed in sub-elite junior and senior rugby league players; high training loads in the early phases of the season are associated with higher injury rates, while reductions in training loads in the competitive phase of the season results in lower training injury rates.5, 6 Despite the reported relationship between training load and injury, there is also evidence to suggest that poor fitness and low training loads contribute to injury risk in rugby league. Gabbett and Domrow7 studied risk factors for injury in sub-elite rugby league players and found that players with poor aerobic fitness and those that had performed less than 18 weeks of pre-season training were at increased risk of injury. Collectively these findings demonstrate an equivocal relationship between training load and injury risk in sub-elite rugby league players.
Despite the wealth of studies documenting the training–injury relationship in sub-elite rugby league players, evidence linking training load and injury in professional players is far from substantive. In the only study to investigate the training loads of professional rugby league players, Killen et al.8 failed to find a relationship between training load and injury over a 14 week pre-season training program. While this study provided important information on the training-injury relationship of elite level team sport athletes, the short training period, and the small number of injuries limits the generalisability of these findings across teams and training periods.
While rugby league involves bouts of high-intensity running, the game includes physical demands that are unique from many other team sports, with the large numbers of collisions and tackles performed during a match contributing to playing intensity and player fatigue. The relationship between training load and injury in rugby league players is further complicated by these contact demands, with players required to perform multiple collisions during training in order to adequately prepare for the most demanding passages of play expected during competition. However, to date, studies of the training load–injury relationship have neglected to differentiate non-contact soft tissue injuries from those that occur as a result of physical contact.
Given that rugby league training loads are manipulated through changes in either running loads, contact loads, or strength and power training loads, it follows that increases in training loads could lead to increases in contact injuries, non-contact injuries, or both. Furthermore, the relationship between different training modalities and injury risk in a separate and different training modality has yet to be determined. With this in mind, the purpose of this study was to investigate the relationship between training load and injury in professional rugby league players.
Section snippets
Methods
Seventy-nine professional rugby league players (mean ± SD age, height, and body mass; 23.3 ± 3.8 years, 183.8 ± 5.6 cm, and 96.1 ± 10.1 kg, respectively) participated in this four-year prospective study (2007–2010). All players were highly motivated players from the same professional rugby league club and were competing in the elite National Rugby League (NRL) competition. Players had completed a 4-week active recovery off-season period, and were free from injury at the commencement of the study. All
Results
A total of 251 training injuries were sustained over the four seasons, giving an overall injury incidence of 10.5 (95% CI, 9.2–11.8) per 1000 training hours. The incidence of non-contact field injuries, contact field injuries, and strength and power injuries was 21.8 (95% CI, 18.5–25.0), 6.1 (95% CI, 4.4–7.8), and 3.4 (95% CI, 2.1–4.7) per 1000 h, respectively.
The incidence of non-contact field injuries resulting in a loss of training time (9.6 [95% CI, 7.4–11.7] per 1000 h) was 2.7–3.2 fold
Discussion
This study investigated the relationship between training loads and injury incidence in professional rugby league players. While previous studies have examined the training–injury relationship in sub-elite rugby league players,3, 4, 5, 6 and during the pre-season in professional rugby league players,8 this study is the first to investigate this relationship in high-performance rugby league players over the course of several competitive seasons. The results of this study demonstrate a
Conclusion
In conclusion, the results of this study demonstrate a significant relationship between training load and injury incidence in professional rugby league players. Field training loads were significantly associated with both contact and non-contact field training injuries, while strength and power loads were significantly associated with injuries sustained in strength and power activities. In addition, while no significant relationship was observed between field training loads and strength and
Practical implications
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This study found significant relationships between training load and injury in professional rugby league players.
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While field training loads were not related to strength and power injuries, strength and power training loads were correlated with field training injuries.
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These findings suggest that the harder rugby league players train, the more injuries they will sustain, and that high strength and power training loads may contribute indirectly to field injuries.
Conflict of interest
No sources of funding were used to conduct this study. The authors have no conflict of interests that are directly relevant to the content of this study.
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