Mixed
Chronic endurance training induces skeletal muscle adaptations, including increased mitochondrial density and capillary supply, which shift fuel reliance toward fat oxidation and reduce glycolytic flux, thereby enhancing endurance performance capacity.
To improve endurance, focus on training that specifically targets your sport's demands. Your body adapts by building more mitochondria and blood vessels, allowing you to burn fat more efficiently and spare glycogen. Don't just add endless miles; ensure your training intensity and duration are sufficient to trigger these adaptations, as there is a point of diminishing returns where more volume adds fatigue without further performance gains.
Endurance training is associated with an increase in the activities of key enzymes of the mitochondrial electron transport chain and a concomitant increase in mitochondrial protein concentration. These morphological changes, along with increased capillary supply, result in a shift in trained muscle to a greater reliance on fat as a fuel with a concomitant reduction in glycolytic flux and tighter control of acid–base status. Taken collectively, these adaptations result in an enhanced performance capacity.
Why this rating
The paper is a comprehensive review by a leading expert (Hawley) citing numerous peer-reviewed studies on human and animal models.
Source
Adaptations Of Skeletal Muscle To Prolonged, Intense Endurance Training
John A. Hawley · Clinical and Experimental Pharmacology and Physiology · 2002
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