Department for Health, University of Bath, Bath, UNITED KINGDOM.
School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UNITED KINGDOM.
Med Sci Sports Exerc. 2020 Jun;52(6):1376-1384. doi: 10.1249/MSS.0000000000002262.
Maximizing carbohydrate availability is important for many endurance events. Combining pectin and sodium alginate with ingested maltodextrin-fructose (MAL + FRU + PEC + ALG) has been suggested to enhance carbohydrate delivery via hydrogel formation, but the influence on exogenous carbohydrate oxidation remains unknown. The primary aim of this study was to assess the effects of MAL + FRU + PEC + ALG on exogenous carbohydrate oxidation during exercise compared with a maltodextrin-fructose mixture (MAL + FRU). MAL + FRU has been well established to increase exogenous carbohydrate oxidation during cycling compared with glucose-based carbohydrates (MAL + GLU). However, much evidence focuses on cycling, and direct evidence in running is lacking. Therefore, a secondary aim was to compare exogenous carbohydrate oxidation rates with MAL + FRU versus MAL + GLU during running.
Nine trained runners completed two trials (MAL + FRU and MAL + FRU + PEC + ALG) in a double-blind, randomized crossover design. A subset (n = 7) also completed a MAL + GLU trial to address the secondary aim, and a water trial to establish background expired CO2 enrichment. Participants ran at 60% V˙O2peak for 120 min while ingesting either water only or carbohydrate solutions at a rate of 1.5 g carbohydrate per minute.
At the end of 120 min of exercise, exogenous carbohydrate oxidation rates were 0.9 (SD 0.5) g·min with MAL + GLU ingestion. MAL + FRU ingestion increased exogenous carbohydrate oxidation rates to 1.1 (SD 0.3) g·min (P = 0.038), with no further increase with MAL + FRU + PEC + ALG ingestion (1.1 (SD 0.3) g·min; P = 1.0). No time-treatment interaction effects were observed for plasma glucose, lactate, insulin, or nonesterified fatty acids, or for ratings of perceived exertion or gastrointestinal symptoms (all, P > 0.05).
To maximize exogenous carbohydrate oxidation during moderate-intensity running, athletes may benefit from consuming glucose(polymer)-fructose mixtures over glucose-based carbohydrates alone, but the addition of pectin and sodium alginate offers no further benefit.
最大化碳水化合物的可用性对于许多耐力项目非常重要。将果胶和藻酸钠与摄入的麦芽糊精-果糖（MAL + FRU + PEC + ALG）结合使用，已被建议通过水凝胶形成来增强碳水化合物的输送，但对外源碳水化合物氧化的影响仍不清楚。本研究的主要目的是评估与麦芽糊精-果糖混合物（MAL + FRU）相比，MAL + FRU + PEC + ALG 在运动期间对外源碳水化合物氧化的影响。与基于葡萄糖的碳水化合物（MAL + GLU）相比，MAL + FRU 已被很好地证明可以增加自行车运动中外源碳水化合物的氧化。然而，大量证据集中在骑自行车上，而在跑步中缺乏直接证据。因此，次要目的是比较在跑步中 MAL + FRU 与 MAL + GLU 相比，外源碳水化合物氧化率的差异。
9 名训练有素的跑步者在双盲、随机交叉设计中完成了两次试验（MAL + FRU 和 MAL + FRU + PEC + ALG）。一小部分（n = 7）还完成了 MAL + GLU 试验以解决次要目的，并完成了水试验以确定背景呼出 CO2 富集。参与者以 60%的 V˙O2peak 速度运动 120 分钟，同时以每分钟 1.5 克碳水化合物的速度摄入仅水或碳水化合物溶液。
在 120 分钟运动结束时，MAL + GLU 摄入的外源碳水化合物氧化率为 0.9（SD 0.5）g·min。MAL + FRU 摄入使外源碳水化合物氧化率增加到 1.1（SD 0.3）g·min（P = 0.038），而 MAL + FRU + PEC + ALG 摄入无进一步增加（1.1（SD 0.3）g·min；P = 1.0）。对于血浆葡萄糖、乳酸、胰岛素或非酯化脂肪酸，或对于感知用力或胃肠道症状的评分，均未观察到时间-处理相互作用效应（所有，P > 0.05）。
为了在中等强度跑步中最大程度地氧化外源碳水化合物，运动员可能受益于消耗葡萄糖（聚合物）-果糖混合物而不是单独的基于葡萄糖的碳水化合物，但添加果胶和藻酸钠没有带来额外的益处。
