Endurance training increases the rate at which acetyl-CoA molecules are formed from free fatty acids for entry to the Krebs cycle.

• A. Increased
• B. Decreased
• C. Unchanged
• D. Not applicable

Answer: (A)

Endurance training boosts fat oxidation by increasing the activity of beta-oxidation enzymes, expanding mitochondrial content, and improving transport of fatty acids into the mitochondria. With more efficient beta-oxidation, fatty acids are broken down into acetyl-CoA more rapidly, raising the rate at which acetyl-CoA is formed for entry into the Krebs cycle. Training also lowers malonyl-CoA inhibition of CPT I during sustained exercise, helping fatty acids enter mitochondria more readily and fueling acetyl-CoA production. This shift supports greater reliance on fat as a fuel during longer efforts, preserving glycogen and sustaining ATP production.