Plasma glucagon and catecholamines during exhaustive short-term exercise

Area of Science:

• Exercise Physiology
• Endocrinology
• Sports Science

Background:

• Understanding the hormonal responses to exercise is crucial for optimizing athletic performance and health.
• High-intensity exercise places significant metabolic demands on the body, requiring rapid adjustments in fuel mobilization.

Purpose of the Study:

• To investigate the changes in plasma glucagon and catecholamine levels during and after exhaustive continuous and intermittent running exercises in male athletes.
• To examine the relationship between these hormonal changes and metabolic markers such as blood lactate, glucose, and cyclic AMP.

Main Methods:

• Male athletes underwent exhaustive 15-minute continuous running and strenuous intermittent running (3 x 300m).
• Plasma levels of glucagon, catecholamines (noradrenaline), cyclic AMP, blood glucose, and blood lactate were measured before and immediately after exercise.

Main Results:

• Intermittent exercise resulted in significantly higher blood lactate levels compared to continuous running.
• Both exercise types led to substantial increases in plasma glucagon (41-55%) and noradrenaline (7.7-9.1 fold).
• Plasma cyclic AMP, blood glucose, and alanine levels were significantly elevated post-exercise.

Conclusions:

• The sympathoadrenal system plays a critical role in regulating liver glucose production during high-intensity exercise.
• Catecholamines directly and indirectly (via glucagon) stimulate hepatic glucose output to meet the energy demands of intense physical activity.