The protein requirement in athletes increases as a result of exercise-induced changes in protein metabolism. In addition, the frequency, quantity, and quality (i.e., leucine content) of the protein intake modulates the protein metabolism. Thus, this study aimed to investigate whether nutritional practice (particularly, protein and amino acid intake at each eating occasion) meets the protein needs required to achieve zero nitrogen balance in elite swimmers during a training camp. Eight elite swimmers (age 21.9 ± 2.3 years, body weight 64.2 ± 7.1 kg, sex M:2 F:6) participated in a four-day study. The nitrogen balance was calculated from the dietary nitrogen intake and urinary nitrogen excretion. The amino acid intake was divided over six eating occasions. The nitrogen balance was found to be positive (6.7 ± 3.1 g N/day, p < 0.05) with protein intake of 2.96 ± 0.74 g/kg/day. The frequency and quantity of leucine and the protein intake were met within the recommended range established by the International Society of Sports Nutrition. Thus, a protein intake of 2.96 g/kg/day with a well-designated pattern (i.e., frequency throughout the day, as well as quantity and quality) of protein and amino acid intake may satisfy the increased need for protein in an elite swimmer.

中文翻译：

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优秀日本游泳选手在训练营中的营养实践和氮平衡

运动引起的蛋白质代谢变化会导致运动员的蛋白质需求增加。另外，蛋白质摄入的频率，数量和质量（即亮氨酸含量）调节蛋白质代谢。因此，本研究旨在调查营养实践（尤其是每次进食时的蛋白质和氨基酸摄入量）是否满足在训练营中精英游泳者实现零氮平衡所需的蛋白质需求。八名精英游泳者（年龄21.9±2.3岁，体重64.2±7.1千克，性别M：2 F：6）参加了为期四天的研究。从饮食中的氮摄入量和尿中的氮排泄量计算出氮平衡。氨基酸摄入量分为六次进食。发现氮平衡为正值（6.7±3.1 g N /天，p<0.05），蛋白质摄入量为2.96±0.74 g / kg /天。亮氨酸的频率和数量以及蛋白质的摄入量均在国际运动营养学会确定的推荐范围内。因此，每天摄入2.96 g / kg / kg的蛋白质和氨基酸具有明确指定的模式（即全天的频率以及数量和质量）可以满足精英游泳者对蛋白质增加的需求。