Buga Alex, Buxton Jeffrey D, Plank Emma, Minor James D, Sterrett Micah T, Brooks Christopher A, Niemann Tanner R, Troxel Margaret P, Bryarly Anthony, Furry Zachary, Hannon Clarra, Muench Jason, Stone Daniel, D'Agostino Dominic P, Volek Jeff S, Koutnik Andrew P, Prins Philip J
Department of Human Sciences, The Ohio State University, Columbus, OH 43210, USA.
Department of Exercise Science, Grove City College, Grove City, PA 16127, USA.
Nutrients. 2025 Aug 27;17(17):2771. doi: 10.3390/nu17172771.
Recent work has challenged the notion that preferred substrate oxidation is a key determinant of exercise performance. This investigation tested middle-distance running performance, in the fed state, to control for glycogen and exercise-induced hypoglycemia (EIH) confounders.
In a randomized crossover fashion, all while controlling dietary intake, activity, and body weight, recreational distance runners completed either a 5K ( = 15; VO: 58.3 ± 6.2 mL/kg/min) or a 10K ( = 15; VO: 54.51 ± 5.9 mL/kg/min) middle-distance run after consuming isocaloric low-carbohydrate high-fat (LCHF) and high-carbohydrate low-fat (HCLF) pre-exercise meals. Time trial (TT) performance (sec), carbohydrate/fat substrate oxidation, blood metabolites, heart rate (HR), ratings of perceived exertion (RPE), and subjective fullness and thirst were measured throughout.
LCHF pre-exercise nutrition reliably altered substrate oxidation and metabolite profiles compared to HCLF, evidenced by significant increases in fat oxidation (77% higher) and reductions in RER (5% lower), with corresponding shifts in carbohydrate oxidation. Despite distinct preferred substrate oxidation profiles during exercise, the 5 and 10 km TT performances were similar between conditions ( = 0.646/ = 0.118). RER was significantly lower ( = 0.002) after the LCHF condition compared to HCLF. Capillary R-βHB increased modestly after LCHF, while blood glucose increased after HCLF only. The LCHF meal was 35% more filling than the HCLF meal. Preferred substrate oxidation did not significantly modulate middle-distance running performance.
This work supports recent findings that substrate oxidation is not a primary determinant of aerobic performance, as previously conceived.
近期研究对“首选底物氧化是运动表现的关键决定因素”这一观点提出了挑战。本研究在进食状态下测试中长跑表现，以控制糖原和运动诱发低血糖（EIH）等混杂因素。
以随机交叉方式，在控制饮食摄入、活动量和体重的同时，业余长跑运动员在食用等热量的运动前低碳水高脂肪（LCHF）和高碳水低脂肪（HCLF）餐食后，分别完成5公里（n = 15；VO₂：58.3 ± 6.2 mL/kg/min）或10公里（n = 15；VO₂：54.51 ± 5.9 mL/kg/min）的中长跑。全程测量计时赛（TT）成绩（秒）、碳水化合物/脂肪底物氧化、血液代谢物、心率（HR）、主观用力程度评分（RPE）以及主观饱腹感和口渴程度。
与HCLF相比，LCHF运动前营养摄入确实改变了底物氧化和代谢物谱，表现为脂肪氧化显著增加（高77%）、呼吸商（RER）降低（低5%），碳水化合物氧化相应改变。尽管运动期间底物氧化偏好不同，但两种情况下5公里和10公里TT成绩相似（P = 0.646/P = 0.118）。与HCLF相比，LCHF条件下RER显著更低（P = 0.002）。LCHF后毛细血管β-羟基丁酸（R-βHB）略有增加，而仅HCLF后血糖升高。LCHF餐比HCLF餐的饱腹感高35%。首选底物氧化并未显著调节中长跑表现。
本研究支持了近期的研究结果，即底物氧化并非如先前设想的那样是有氧运动表现的主要决定因素。
