Miller W C, Bryce G R, Conlee R K
J Appl Physiol Respir Environ Exerc Physiol. 1984 Jan;56(1):78-83. doi: 10.1152/jappl.1984.56.1.78.
Eighty-seven male Sprague-Dawley rats (245-300 g) were randomly assigned to one of two experimental groups. The first group consumed a diet high in fat and low in carbohydrate (LCD), whereas the second group ate a normal diet (ND). After either 1 or 5 wk on the diets, rats from each group were killed either before or after an exhausting run on a rodent treadmill (35 m X min-1, 0% grade). The LCD animals ran significantly longer before exhaustion at both week 1 (44.9 +/- 5.1 vs. 41.6 +/- 4.2 min) and week 5 (47.1 +/- 3.6 vs. 35.5 +/- 3.1 min) (P less than 0.05). Adaptations to the LCD included lower muscle and liver glycogen content, decreased rate of glycogen breakdown during exercise, decreased lactate production, and elevated blood ketone levels. In addition to these substrate changes, the LCD caused increased enzyme activities of muscular 3-hydroxyacyl-CoA dehydrogenase (35-110%) and citrate synthase (15-20%). These data indicate that rats exposed to a high-fat diet are capable of prolonged intense exercise in spite of limited glycogen stores. This improved capacity for exercise appears to be partially the result of muscular adaptations to the diet, which apparently increase the ability to oxidize fat and concomitantly spare glycogen.
87只雄性斯普拉格-道利大鼠（体重245 - 300克）被随机分为两个实验组。第一组食用高脂肪低碳水化合物饮食（LCD），而第二组食用正常饮食（ND）。在饮食1周或5周后，每组大鼠在啮齿动物跑步机上进行力竭跑步（速度35米/分钟，坡度0%）之前或之后被处死。在第1周（44.9±5.1分钟对41.6±4.2分钟）和第5周（47.1±3.6分钟对35.5±3.1分钟）时，LCD组动物在力竭前的跑步时间显著更长（P<0.05）。对LCD饮食的适应性变化包括肌肉和肝脏糖原含量降低、运动期间糖原分解速率下降、乳酸生成减少以及血酮水平升高。除了这些底物变化外，LCD饮食还导致肌肉中3-羟酰基辅酶A脱氢酶（35 - 110%）和柠檬酸合酶（15 - 20%）的酶活性增加。这些数据表明，尽管糖原储备有限，但食用高脂肪饮食的大鼠仍能够进行长时间的剧烈运动。这种运动能力的提高似乎部分是由于肌肉对饮食的适应性变化，这显然增加了氧化脂肪的能力并同时节省了糖原。
