Carbohydrates are critical for high‐intensity exercise performance. However, the effects of carbohydrate supplementation on muscle metabolism and performance during short‐duration high‐intensity intermittent exercise remain inadequately explored. Our aim was to address this aspect in a randomized, counterbalanced, double‐blinded crossover design. Eleven moderately‐to‐well‐trained males performed high‐intensity intermittent cycling receiving carbohydrate (CHO, ~55 g/h) or placebo (PLA) fluid supplementation. Three exercise periods (EX1‐EX3) were completed comprising 10 × 45 s at ~105% Wmax interspersed with 135 s rest between bouts and ~20 min between periods. Repeated sprint ability (5 × 6 s sprints with 24 s recovery) was assessed at baseline and after each period. Thigh muscle biopsies were obtained at baseline and before and after EX3 to determine whole‐muscle and fiber‐type‐specific glycogen depletion. No differences were found in muscle glycogen degradation at the whole‐muscle (p = 0.683) or fiber‐type‐specific level (p = 0.763–0.854) with similar post‐exercise whole‐muscle glycogen concentrations (146 ± 20 and 122 ± 15 mmol·kg−1 dw in CHO and PLA, respectively). Repeated sprint ability declined by ~9% after EX3 with no between‐condition differences (p = 0.971) and no overall differences in ratings of perceived exertion (p = 0.550). This was despite distinctions in blood glucose concentrations throughout exercise, reaching post‐exercise levels of 5.3 ± 0.2 and 4.1 ± 0.2 mmol·L−1 (p < 0.001) in CHO and PLA, respectively, accompanied by fivefold higher plasma insulin levels in CHO (p < 0.001). In conclusion, we observed no effects of carbohydrate ingestion on net muscle glycogen breakdown or sprint performance during short‐duration high‐intensity intermittent exercise despite elevated blood glucose and insulin levels. These results therefore question the efficacy of carbohydrate supplementation strategies in high‐intensity intermittent sports.

中文翻译：

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碳水化合物摄入对短期高强度间歇性运动期间的肌肉代谢或表现没有影响


碳水化合物对于高强度运动表现至关重要。然而，碳水化合物补充剂对短期高强度间歇性运动期间肌肉代谢和表现的影响仍未得到充分探索。我们的目标是通过随机、平衡、双盲交叉设计来解决这一问题。11 名受过中等训练的男性进行了高强度间歇性循环，接受了碳水化合物 （CHO， ~55 g/h） 或安慰剂 （PLA） 液体补充。完成了三个运动期 （EX1-EX3），包括 10 × 45 秒，~105% Wmax，穿插着两次休息 135 秒，两次之间休息 ~20 分钟。在基线和每个时期后评估重复冲刺能力 （5 × 6 s sprint，恢复 24 s）。在基线以及 EX3 前后进行大腿肌肉活检，以确定全肌肉和纤维类型特异性糖原耗竭。在全肌肉 （p = 0.683） 或纤维类型特异性水平 （p = 0.763-0.854） 的肌糖原降解未发现差异，运动后全肌糖原浓度相似 （146 ± 20 和 122 ± 15 mmol·kg-1 dw，CHO 和 PLA 中分别为 15 mmol·kg-1 dw）。EX3 后重复冲刺能力下降了 ~9%，条件间没有差异 （p = 0.971），感知用力评分没有总体差异 （p = 0.550）。尽管整个运动过程中的血糖浓度存在差异，但运动后血糖浓度达到 5.3 ± 0.2 和 4.1 ± 0.2 mmol·CHO 和 PLA 中的 L-1 （p < 0.001） 分别伴随着 CHO 血浆胰岛素水平高出五倍 （p < 0.001）。 总之，尽管血糖和胰岛素水平升高，但我们观察到碳水化合物摄入对短期高强度间歇性运动期间的净肌糖原分解或冲刺表现没有影响。因此，这些结果质疑碳水化合物补充策略在高强度间歇性运动中的疗效。