Glycogen sparing in endurance performance is achieved by which adaptation?

Glycogen sparing in endurance performance is achieved by which adaptation?

• A. Increasing glycolytic enzyme activity to spare glycogen.
• B. Decreasing fat oxidation to use more glycogen.
• C. Relying more on fat oxidation to preserve glycogen.
• D. Reducing mitochondrial capacity.

Answer: (C)

Glycogen sparing in endurance performance comes from shifting energy use toward fat oxidation during steady, submaximal work. When the body becomes better at burning fat for fuel, it relies less on glycogen stores, which are limited and run out sooner. This is advantageous because fat stores are abundant, and fat oxidation can sustain energy production for a longer duration at moderate intensities, helping delay fatigue. Training adaptations increase mitochondrial density and the capacity to oxidize fatty acids, enabling more ATP to be produced from fats without tapping into glycogen as rapidly. If the body were to rely more on glycolysis or carbohydrate pathways, glycogen would be depleted faster, compromising endurance. Conversely, increasing fat oxidation capacity supports glycogen preservation, while reducing mitochondrial capacity or fat use would lessen the ability to spare glycogen.