Metabolic adaptation to prolonged exercise.

Area of Science:

• Exercise Physiology
• Human Metabolism
• Sports Science

Background:

• Endurance events challenge metabolic homeostasis.
• Understanding substrate utilization is key to optimizing performance and recovery.

Purpose of the Study:

• To investigate the role of substrate supply in healthy subjects after varying long-distance running events.
• To analyze metabolic responses to 10 km, 25 km, and marathon races.

Main Methods:

• Study involved 50 healthy subjects participating in 10 km, 25 km, and marathon races.
• Metabolic variables related to carbohydrate and lipid metabolism were measured post-exercise.

Main Results:

• Carbohydrate metabolism markers (glucose, lactate, pyruvate) were highest in 10-km runners.
• Marathon runners exhibited decreased insulin, increased glucagon and cortisol, and higher free fatty acids, beta-hydroxybutyrate, and acetoacetate.
• Glycogen depletion is a limiting factor up to 90 minutes; beyond this, metabolic shifts indicate increased reliance on fat and ketone bodies.

Conclusions:

• Metabolic responses differ significantly based on endurance event duration.
• Glycogen availability is critical for shorter endurance events, while longer events necessitate a shift towards fat and ketone metabolism.
• Hormonal changes (insulin, glucagon, cortisol) reflect these distinct metabolic adaptations.