ABSTRACT
The question of how much dietary protein is necessary for optimal athletic performance has been debated in the scientific literature for over 100 years (Butterfield, 1991; Cathcart, 1925; Dunlop et al., 1897; Lemon, 1991a; von Liebig, 1842) and probably among athletes since the time of the ancient Greeks. Despite this long history surprisingly little information is available and no consensus exists. Due in part to the complexity of protein metabolism and the associated methodological difficulties, exercise protein metabolism has received relatively little attention in comparison to carbohydrate and fat metabolism. Current recommended protein intakes from a number of expert committees on nutrition throughout the world range from 0.8 (Canadian Department of National Health and Welfare, 1983; US Food and Nutrition Board, 1989; Food and Agricultural Organization, 1985) to 1.0 (Australian National Health and Medical Research Council, 1987; Dutch Nutrition Board, 1988 – for women) or 1.2 g/kg·d−1 (Dutch Nutrition Board, 1988 – for men). These recommen dations are based primarily on nitrogen balance data (nitrogen intake minus nitrogen excretion) from individuals who were essentially sedentary. Although several of these committees acknowledged that exercise may increase protein need, especially when attempts are made to increase muscle mass (strength exercise), only one suggested an increased intake (1.5 g/kg·d−1) for active individuals (Dutch Nutrition Board, 1988). Despite this general lack of agreement regarding protein recommendations for those involved in regular, strenuous exercise a substantial amount of information exists indicating that protein needs are higher for these individuals. This chapter summarizes some of this information in an attempt to (a) identify the key factors responsible for any increased protein need associated with exercise and (b) provide dietary recommendations for different types of athletes. The benefits/hazards of individual amino acid supplementation have been reviewed recently (Lemon, 1991b) and will not be repeated here.
