The timing of carbohydrate ingestion and how this influences net muscle glycogen utilization and fatigue has only been investigated in prolonged cycling. Past findings may not translate to running because each exercise mode is distinct both in the metabolic response to carbohydrate ingestion and in the practicalities of carbohydrate ingestion. To this end, a randomized, cross-over design was employed to contrast ingestion of the same sucrose dose either at frequent intervals (15 × 5 g every 5 min) or at a late bolus (1 × 75 g after 75 min) during prolonged treadmill running to exhaustion in six well-trained runners (V˙O2max 61 ± 4 ml·kg-1·min-1). The muscle glycogen utilization rate was lower in every participant over the first 75 min of running (Δ 0.51 mmol·kg dm-1·min-1; 95% confidence interval [-0.02, 1.04] mmol·kg dm-1·min-1) and, subsequently, all were able to run for longer when carbohydrate had been ingested frequently from the start of exercise compared with when carbohydrate was ingested as a single bolus toward the end of exercise (105.6 ± 3.0 vs. 96.4 ± 5.0 min, respectively; Δ 9.3 min, 95% confidence interval [2.8, 15.8] min). A moderate positive correlation was apparent between the magnitude of glycogen sparing over the first 75 min and the improvement in running capacity (r = .58), with no significant difference in muscle glycogen concentrations at the point of exhaustion. This study indicates that failure to ingest carbohydrates from the outset of prolonged running increases reliance on limited endogenous muscle glycogen stores-the ergolytic effects of which cannot be rectified by subsequent carbohydrate ingestion late in exercise.

中文翻译：

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相对于单次推注，频繁摄入碳水化合物可减少肌肉糖原消耗并延缓疲劳。

碳水化合物摄入的时间以及这如何影响净肌糖原利用和疲劳仅在长时间骑行中进行了研究。过去的研究结果可能不会转化为跑步，因为每种运动模式在对碳水化合物摄入的代谢反应和碳水化合物摄入的实用性方面都是不同的。为此，采用随机交叉设计来对比在长时间内以频繁间隔（每 5 分钟 15 × 5 克）或后期推注（75 分钟后 1 × 75 克）摄入相同剂量的蔗糖。六名训练有素的跑步者在跑步机上跑到筋疲力尽（V˙O2max 61 ± 4 ml·kg-1·min-1）。在跑步的前 75 分钟内，每位参与者的肌糖原利用率均较低（Δ 0.51 mmol·kg dm-1·min-1；95% 置信区间 [-0.02, 1.04] mmol·kg dm-1·min- 1) 并且随后，与运动结束时单次摄入碳水化合物相比，当碳水化合物从运动开始时经常摄入时，所有人都能够跑更长的时间（分别为 105.6 ± 3.0 和 96.4 ± 5.0 分钟；Δ 9.3 分钟， 95% 置信区间 [2.8, 15.8] 分钟）。前 75 分钟的糖原节省量与跑步能力的改善之间存在中度正相关（r = .58），在力竭时肌糖原浓度没有显着差异。这项研究表明，在长时间跑步开始时未能摄入碳水化合物会增加对有限的内源性肌糖原储存的依赖——运动后期随后摄入碳水化合物不能纠正这种作用。