低碳水化合物飲食對運動訓練與表現之影響

Effects of low carbohydrate diet on exercise training and performance

高強度運動訓練時，醣類是主要的能源，因此，運動員常被建議攝取高碳水化合物飲食，以增進運動表現。不過，研究指出，低碳水化合物飲食 (low-carbohydrate diet, LCHD) 結合運動，能動員更多脂肪酸轉換為酮體 (ketone bodies)，以作為體內主要能量的來源，除了有助於體重控制外，也能降低代謝症候群的罹患。然而，LCHD在改善身體組成的同時，是否會影響到運動訓練的進行和效益呢？本文藉由LCHD相關文獻蒐集，以探討LCHD對身體組成、運動訓練與隨後運動表現的影響。綜合文獻結果發現：一、LCHD必須執行兩週以上，身體組織才能有效地運用酮體作為能量，即產生酮體適應，有助於耐力運動表現和身體組成的改善；二、高強度間歇訓練時，兩週LCHD的介入，可提升最大攝氧量表現、保留肌肉量與阻抗素 (resistin)；三、體操、自行車與跆拳道選手，在二週以上的LCHD介入下，仍能可以維持正常的訓練強度，不影響運動表現。儘管過去的教練與選手皆認為，高碳水化合物的攝取才能維持高強度的運動訓練及增加運動表現，然而兩週以上的LCHD，不僅不會影響運動訓練的效益，也能同時改善身體組成，甚至提升運動表現。期望文獻整理的結果，能提供給運動選手，在賽期時體重控制與運動表現之另一種可行的飲食選擇。

As carbohydrate is the main fuel source during high-intensity exercise training, high carbohydrate diet is recommended for athletes to improve exercise performance. However, studies have indicated that fatty acids are converted to ketone bodies and used as a fuel source when low-carbohydrate diet (LCHD) is performed. In addition, when LCHD combined with exercise, body composition can be improved and risks of metabolic syndromes can be reduced. Whether LCHD affects exercise training and exercise performance requires clarification. Previous studies have shown that: 1. At least 2 weeks of LCHD is needed for keto-adaptation to take place and keto-adaptation has been shown to improve exercise performance and body composition. 2. During high-intensity interval training, Keto-adaptation has been shown to improve maximal oxygen consumption and preserve muscle mass and resistin. 3. Two weeks of LCHD intervention has been shown to decrease body weight and body fat without negatively effects on strength performance in artistic gymnasts, cyclists, and Taekwondo. Although the coaches and athletes still believe that high carbohydrate diet is necessary to m and aintain high-intensity exercise training and increase athletic performance, two weeks of LCHD intervention does not affect exercise training. In contrast, LCHD may improve body composition and even enhance athletic performance. LCHD can be used as an alternative diet for weight control and performance for some athletes.