It was previously demonstrated that postexercise ingestion of fructose–glucose mixtures can lead to superior liver and equal muscle glycogen synthesis as compared with glucose-based carbohydrates (CHOs) only. After an overnight fast, liver glycogen stores are reduced, and based on this we hypothesized that addition of fructose to a glucose-based breakfast would lead to improved subsequent endurance exercise capacity. In this double-blind cross-over randomized study (eight males, peak oxygen uptake: 62.2 ± 5.4 ml·kg⁻¹·min⁻¹), participants completed two experimental trials consisting of two exercise bouts. In the afternoon of Day 1, they completed a cycling interval training session to normalize glycogen stores after which a standardized high-CHO diet was provided for 4 hr. On Day 2, in the morning, participants received 2 g/kg of CHOs in the form of glucose and rice or fructose and rice, both in a CHO ratio of 1:2. Two hours later they commenced cycling exercise session at the intensity of the first ventilatory threshold until task failure. Exercise capacity was higher in fructose and rice (137.0 ± 22.7 min) as compared with glucose and rice (130.06 ± 19.87 min; p = .046). Blood glucose and blood lactate did not differ between the trials (p > .05) and neither did CHO and fat oxidation rates (p > .05). However, due to the duration of exercise, total CHO oxidation was higher in fructose and rice (326 ± 60 g vs. 298 ± 61 g, p = .009). Present data demonstrate that addition of fructose to a glucose-based CHO source at breakfast improves endurance exercise capacity. Further studies are required to determine the mechanisms and optimal dose and ratio.

先前已经证明，与仅基于葡萄糖的碳水化合物 (CHO) 相比，运动后摄入果糖-葡萄糖混合物可以导致更好的肝脏和相同的肌糖原合成。禁食一夜后，肝糖原储备减少，基于此，我们假设在以葡萄糖为基础的早餐中添加果糖会提高随后的耐力运动能力。在这项双盲交叉随机研究中（8 名男性，吸氧峰值：62.2 ± 5.4 ml·kg ^-1 ·min ^-1)，参与者完成了两个实验性试验，包括两个锻炼回合。在第 1 天的下午，他们完成了一次自行车间歇训练以使糖原储存正常化，之后提供 4 小时的标准化高 CHO 饮食。在第 2 天的早上，参与者接受了 2 g/kg 的 CHO，以葡萄糖和大米或果糖和大米的形式，两者的 CHO 比例均为 1:2。两小时后，他们以第一个通气阈值的强度开始骑自行车锻炼，直到任务失败。果糖和大米的运动能力（137.0 ± 22.7 分钟）高于葡萄糖和大米（130.06 ± 19.87 分钟；p  = .046）。试验之间的血糖和血乳酸没有差异（p  > .05），CHO和脂肪氧化率也没有差异（p  > .05)。然而，由于运动时间长，果糖和大米中的总 CHO 氧化水平较高（326 ± 60 g 对 298 ± 61 g，p  = .009）。目前的数据表明，在早餐时将果糖添加到基于葡萄糖的 CHO 源中可以提高耐力运动能力。需要进一步的研究来确定机制以及最佳剂量和比例。