Endurance training reduces the stimulation of glycolysis, leading to which effect on oxygen deficit?

• A. Lower oxygen deficit
• B. Higher oxygen deficit
• C. No change in oxygen deficit
• D. Increased oxygen debt

Answer: (A)

Endurance training boosts the muscle’s ability to produce energy aerobically. With more mitochondria, greater oxidative enzyme activity, and better capillary supply, the muscles can generate ATP via oxidative phosphorylation more quickly when exercise begins. This means less need to rely on anaerobic glycolysis right away, so the initial gap between oxygen supply and demand (the oxygen deficit) is smaller. In other words, aerobic metabolism takes over sooner, reducing the amount of oxygen that's temporarily short of what’s required. The other options imply more anaerobic contribution or no change, which doesn’t fit the adaptations seen with endurance training.