Rugby league is a physically demanding, high intensity collision sport requiring a multidisciplinary skill set of sprinting, tackling, accelerating, decelerating and changing direction(Gabbett et al., 2008). Due to the nature and volume of the contact and high intensity effort in rugby league, injuries are common (Gabbett, 2003a). It has been identified as one of the most injurious sports for players 5-14 years (31.4 injuries/100,000 persons) and 15-34 years (55.6 injuries/100,000 persons) (Centre, 2006; Statistics, 2003). Musculoskeletal injuries (Gabbett, 2003a), categorised as contact or non-contact injuries are common. High incidences of soft tissue injury have been previously observed in training and matches (Gabbett, 2004b). Recently, injury incidence of 37.1 injuries per 1000 hours was observed in junior elite players, predominantly during match play (90%)
The ankle and head/face were most frequently injured (Orr and Cheng, 2016). Previously junior rugby league match injury rates have been observed to range from 1 to 197 per 1000 playing hours, while amateur match injury rates ranging from 134 to 701 per 1000 playing hours have been documented. Semi-professional participation has observed the highest injury rates, ranging from 115 to 825, with professional level injury rates ranging from 58 to 211 per 1000 playing hours (King et al., 2010b).
The physiological demands of rugby league, both in competition and training, increase sharply from junior elite to sub-elite levels (Gabbett et al., 2008). Higher incidence of injury has been observed with higher playing intensities and higher competition levels (Gabbett, 2000; 2001a; Stephenson et al., 1996). Thus, as younger players are selected to compete against older, more experienced athletes for positions at sub-elite and elite level competition it is important to monitor the effects of these increased physiological demands on the developing athlete.
Injury risk in rugby league players is associated with multifactorial parameters which can be broadly categorized as external or internal influences (Drew and Finch, 2016). External influences include, but are not limited to, physiological demands, playing experience/competition level, match and training intensity, preseason preparation and the input of support staff. Increased physiological demands are a key factor in the increases observed in negative outcomes such as injury associated with higher playing intensities and competitive levels (Gabbett, 2005). Match duration increases from 6070 minutes at junior level to 80 minutes at senior level. Junior elite level players typically train 3 days per week for approximately 6 hours in total, whereas sub-elite level players generally train 4-5 days per week for approximately 12-18 hours per week. A recent study in Australian Football players found significant effects of increased duration of training and match play on injury incidence of emerging players when compared with established elite level players (Fortington et al., 2016). Increased training injuries have been observed in the earlier stages of a season (i.e. pre-season) when training intensity and duration are high (Gabbett, 2003b), while match injuries increase progressively throughout the course of a season (Gabbett, 2000; Gabbett, 2003b), and in total, exceed training injuries (Brito et al., 2012; Brooks et al., 2008; King et al., 2010a). Additionally, higher incidence of injury has been observed in rugby league players who undertake
The internal influences that may impact injury in rugby league players include age/maturation, body composition (Fortington et al., 2016; Gabbett, 2000; 2001a) and physiological characteristics (strength, power, speed, agility and aerobic capacity) (Gabbett et al., 2008; Meir, 1994). In addition, inter-relationships between these factors have been observed. For example, age and maturation demonstrate a significant effect on body mass, muscular power, speed, agility, and estimated maximal aerobic power (Gabbett, 2002). Compared to professional rugby league athletes, junior elite players have significantly lower body mass, mesomorphy and greater skinfold thickness (Cheng et al., 2014). Increases in body mass of 12.9 kg in forwards and 12.1 kg in backs between the ages of 14 and 18 with further increases of 9.8 kg in forwards and 8.2 kg in backs between under 19 and open age sub-elite players have been observed (Gabbett, 2002). The physiological characteristics of junior elite through to sub-elite players have been well established (Cheng et al., 2014; Gabbett, 2002). Lower levels of muscular power, speed, agility and aerobic capacity have all been observed between junior elite and sub-elite players (Gabbett, 2002). These physiological characteristics specifically have been linked to increased injury incidence in developing players (Gabbett and Domrow, 2005). Defensive performance and tackle proficiency in sub elite players have been associated with greater lower-body muscle power (Gabbett et al. 2009), height and body mass (Gabbett, 2009). Furthermore, these key tackle performance indicators have been linked to increased injury incidence (Cheng et al., 2014).
Due to the multifaceted nature of injury risk in emerging rugby league players it is imperative consideration is given to the implementation of injury prevention programs, particularly at the developmental levels where resources are often inadequate. Such programs should be multilayered and sequential in nature. This approach should include identification of the extent and nature of injury issues facing the organization, specifically incidence, types, sites and mechanisms of common injuries. Only then can appropriate injury prevention programs based on the aetiology previously identified be put in place. Finally, the program must be evaluated in order to provide insight into its effectiveness and potential future directions. Van Mechelen (1992) has previously described such modelling.
Injuries resulting in lost matches may influence team selections, alter team structure, reduce cohesion between players, and in turn, have a profound impact on team performance. At both the elite and sub-elite levels in sport it is critical to have the maximum number of players available for selection throughout the season (Gabbett, 2004a; Orchard, 2009). Sub-elite development squads typically form the pathway from junior elite to professional level competition. As such they are predominantly younger players (17-19 years) with little to no full time training experience. Limited experience with lengthy (>12 weeks) demanding...