Aerenhouts, D., Poortmans, J. R., Deriemaeker, P., Hebbelinck, M., & Clarys, P. (2010). Protein needs in adolescent sprint athletes: a longitudinal study. Presentation 795 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

This study estimated the protein needs for adolescent sprint athletes. A seven-day diet diary, during which period 2 x 24-hour urine samples were collected, was administered five times with six-month intervals to adolescent sprint athletes (M = 33; F = 32). Anthropometric data were collected allowing the estimation of skeletal muscle mass. Diaries were analyzed for nutrient intakes using the Belgian and Dutch food data banks. A cut-off value of 1.1 x basal metabolic rate was used to check for underreporting. During the 24-hour urine collections, Ss ingested 3 x 180 mg of para-amino benzoate. Urine collections containing a minimum of 85% para-amino benzoate were analyzed for their nitrogen content.

Mean daily protein intakes remained within a narrow range of ~1.4 - 1.5 g/kg in girls and ~1.5 - 1.6 g/kg in boys. For both genders, a protein intake around 1.4 g/kg was required to be in a positive nitrogen balance. This remained stable throughout the experimental period. Height and weight evolution was comparable to that of Belgian peers. A gain in body height, weight, or skeletal muscle mass did not alter nitrogen balance in either gender. There was no significant relationship between protein intake and a gain in height, weight, or skeletal muscle mass.

Implication. A daily protein intake between ~1.3-1.5 g/kg appears adequate to sustain a positive nitrogen balance in adolescent male and female sprint athletes. Sufficient protein was provided through the diet in most of the athletes studied.

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