Rugby league football is played in several countries worldwide. A rugby league team consists of 13 players (6 forwards and 7 backs), with matches played over two 40-minute halves separated by a 10-minute rest interval. Several studies have documented the physiological capacities of rugby league players and the physiological demands of competition, with the physiological capacities of players and the physiological demands of competition increasing as the playing level is increased. However, there is also evidence to suggest that the physiological capacities of players may deteriorate as the season progresses, with reductions in muscular power and maximal aerobic power and increases in skinfold thickness occurring towards the end of the rugby league season, when training loads are lowest and match loads and injury rates are at their highest. Player fatigue and playing intensity have been suggested to contribute to injuries in rugby league, with a recent study reporting a significant correlation (r=0.74) between match injury rates and playing intensity in semi-professional rugby league players. Studies have also reported a higher risk of injury in players with low 10-m and 40-m speed, while players with a low maximal aerobic power had a greater risk of sustaining a contact injury. Furthermore, players who completed <18 weeks of training prior to sustaining their initial injury were at greater risk of sustaining a subsequent injury. These findings provide some explanation for the high incidence of fatigue-related injuries in rugby league players and highlight the importance of speed and endurance training to reduce the incidence of injury in rugby league players. To date, most, but not all, studies have investigated the movement patterns and physiological demands of rugby league competition, with little emphasis on how training activities simulate the competition environment. An understanding of the movement patterns and physiological demands of specific individual positions during training and competition would allow the development of strength and conditioning programmes to meet the specific requirements of these positions. In addition, further research is required to provide information on the repeated effort demands of rugby league. A test that assesses repeated effort performance and employs distances, tackles and intensities specific to rugby league, while also simulating work-to-rest ratios similar to rugby league competition, is warranted.