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 comes from shifting energy use toward fat during sustained aerobic work. With endurance training, muscles enhance their capacity to oxidize fat by increasing mitochondrial density and the activity of fat-burning enzymes, and by improving fatty acid transport into mitochondria. This lets a larger portion of the energy come from fat rather than glycogen, so glycogen stores deplete more slowly and fatigue sets in later at the same intensity. The other ideas would push the body toward greater carbohydrate use or reduce fat oxidation or overall oxidative capacity, which wouldn’t help preserve glycogen. So relying more on fat oxidation to preserve glycogen best explains glycogen sparing.

Glycogen sparing comes from shifting energy use toward fat during sustained aerobic work. With endurance training, muscles enhance their capacity to oxidize fat by increasing mitochondrial density and the activity of fat-burning enzymes, and by improving fatty acid transport into mitochondria. This lets a larger portion of the energy come from fat rather than glycogen, so glycogen stores deplete more slowly and fatigue sets in later at the same intensity. The other ideas would push the body toward greater carbohydrate use or reduce fat oxidation or overall oxidative capacity, which wouldn’t help preserve glycogen. So relying more on fat oxidation to preserve glycogen best explains glycogen sparing.