Effect of prolonged physical exercise on fluid regulating hormones.

Area of Science:

• Endocrinology
• Exercise Physiology
• Cardiovascular Physiology

Background:

• Prolonged physical exercise significantly impacts fluid balance and hormonal regulation.
• Atrial natriuretic peptide (ANP) and cyclic guanosine monophosphate (cGMP) are key regulators of cardiovascular homeostasis.
• Understanding the interplay between exercise, ANP/cGMP, and volume-regulating hormones is crucial for exercise science.

Purpose of the Study:

• To investigate the dynamic changes in atrial natriuretic peptide (ANP) and cyclic guanosine monophosphate (cGMP) following a marathon.
• To examine the relationship between ANP/cGMP and alterations in plasma volume (PV), plasma proteins, and key hormones (AVP, renin, aldosterone).
• To determine the role of ANP and other volume-regulating hormones during and after prolonged exercise.

Main Methods:

• Sixteen well-trained male subjects completed a test marathon.
• Blood samples were collected pre-exercise, immediately post-exercise, and at 3 and 31 hours post-exercise.
• Measurements included plasma ANP, cGMP, PV, plasma proteins, AVP, renin, aldosterone, potassium, and sodium.

Main Results:

• Immediately post-marathon, plasma ANP and cGMP levels doubled, while PV decreased by 7.4%.
• Renin, aldosterone, and arginine vasopressin (AVP) secretion were significantly stimulated post-exercise.
• Thirty-one hours post-marathon, PV increased by 10% and plasma proteins returned to baseline; ANP and cGMP levels normalized.

Conclusions:

• ANP and other volume-regulating hormones play a significant role during and immediately after prolonged exercise.
• The observed increase in PV during the recovery phase is likely due to plasma protein influx into the vascular space.
• The hormonal and volume regulatory effects of intense exercise are transient and resolve within the later recovery period.