Quantitative assessment of human muscle glycogen granules size and number in subcellular locations during recovery from prolonged exercise

Muscle glycogen was reduced to 36 ± 8.3 mmol glucosyl units (kg dry weight)(-1) at exhaustion.

• Muscle glycogen repletion occurred primarily in the intramyofibrillar space after exercise.
• The rate of glycogen granule number increased by 186% in the first 4 hours post-exercise.
• No change in granule size was observed during the initial 4 hours of recovery.
• From 4 to 48 hours post-exercise, granule size increased while the number remained unchanged.
• The synthesis rate of glycogen volume was 50% greater in the subsarcolemmal compartment compared to the myofibrillar compartment.
• Single-particle volume synthesis rates were greater in the myofibrillar compartment than in the subsarcolemmal compartment.

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