Long-Slow-Distance-Training (LSDT) totally depletes....

• A. Muscle glycogen
• B. Blood glucose
• C. Fat stores
• D. Glycogen stores

Answer: (D)

Glycogen depletion during long, slow-distance work happens across the body's energy reserves, not just in one spot. As the duration increases, both muscle glycogen (fuel inside working muscles) and liver glycogen (which helps keep blood glucose up) are used. Over time, these glycogen stores can be exhausted, shifting the body toward fat oxidation and reducing performance. Blood glucose is maintained by liver glycogen breakdown, so it isn’t typically totally depleted during a typical LSDT session. Fat stores are large and not rapidly exhausted in this scenario, so they aren’t the primary depleted reserve. That makes glycogen stores the best answer, since it encompasses the essential energy depletion that drives the metabolic shift during prolonged submaximal exercise.