Nutrients · 2025
Substrate Oxidation Does Not Influence Middle Distance Running Performance: A Randomized Controlled Crossover Trial.
СтатьяРандомизированное исследованиеНазвание и аннотация: Перевод в очереди
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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
Аннотация
OBJECTIVE: 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.
METHODS: In a randomized crossover fashion, all while controlling dietary intake, activity, and body weight, recreational distance runners completed either a 5K (n = 15; VO2max: 58.3 ± 6.2 mL/kg/min) or a 10K (n = 15; VO2max: 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.
RESULTS: 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 (p = 0.646/p = 0.118). RER was significantly lower (p = 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.
CONCLUSION: This work supports recent findings that substrate oxidation is not a primary determinant of aerobic performance, as previously conceived.
METHODS: In a randomized crossover fashion, all while controlling dietary intake, activity, and body weight, recreational distance runners completed either a 5K (n = 15; VO2max: 58.3 ± 6.2 mL/kg/min) or a 10K (n = 15; VO2max: 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.
RESULTS: 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 (p = 0.646/p = 0.118). RER was significantly lower (p = 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.
CONCLUSION: This work supports recent findings that substrate oxidation is not a primary determinant of aerobic performance, as previously conceived.