Research
Macro partitioning
Endurance training increases absolute rates of fat oxidation but does not change the relative balance of substrate utilization (CHO vs. fat) when exercise is performed at the same relative intensity (percentage of VO2max).
Endurance training makes you faster and allows you to burn more fat in absolute terms, but your body still relies primarily on carbohydrates for energy at any given percentage of your maximum effort. Do not expect training alone to make you a 'fat-burning machine' at high intensities.
StrongQualifiesHIGH confidence
when tested at the same relative intensity (65 % of pre- and post-training VO2max), RER values (0.95), leg RQ (0.98), net FFA uptake and muscle TG utilization were not different... these data demonstrate that the balance of substrate utilization was unaffected by prior endurance training and that CHO-derived energy sources are the major fuel source for working muscle even during 1 h of moderate-intensity exercise.
Why this rating
Based on multiple studies using direct biopsy and isotopic tracer techniques in trained subjects.
Source
Carbohydrate Dependence During Prolonged, Intense Endurance Exercise
John A. Hawley et al. · Sports Medicine · 2015
narrative_reviewCited 166×
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