Field hockey is a sport with a long history that has undergone quite rapid and radical change within the past decade. The advent of the synthetic playing surface has changed the technical, tactical and physiological requirements of the game at all levels, but in particular at the elite level. In order to cope with the technical evolution within the game, the hockey player has also had to develop physiologically to meet the physical standards required at elite levels. Analysis of the physiological cost and energy expenditure of playing hockey has placed it in the category of 'heavy exercise', with reported VO2 values during a game of 2.26 L/min. Energy expenditure has been estimated to range from 36 to 50 kJ/min. Physiological profiling of female hockey players has shown that somatotype tends towards 3.5/4.0/2.5. Figures for percentage body fat in female players range from 16 to 26%. Anaerobic power output has been shown to compare favourably with other groups of sportswomen and has also been shown to be a discriminating factor between elite and county level female players. Aerobic power amongst female players has been shown to range from 45 to 59 ml/kg/min. The reported somatotypes of male hockey players have shown considerable variation but there seems to be a trend away from ectomorphy towards mesomorphy. Anaerobic power output in male players has been shown to be the same as that of soccer players and better than other sports, e.g. basketball and also higher than reference norms. The range of aerobic power reported in the literature is 48 to 65 ml/kg/min and it would appear that an aerobic power in excess of 60 ml/kg/min is required for elite level play. The physical strain of hockey play has been shown to be considerable, in particular with respect to spinal shrinkage. There is a greater injury risk inherent in playing on synthetic surfaces than on grass.