Exaggerated ANF response to exercise in middle-aged vs. young runners.

Area of Science:

• Exercise Physiology
• Endocrinology
• Sports Medicine

Background:

• Marathon running induces significant physiological stress.
• Hormonal and electrolyte balance are crucial for performance and safety during endurance events.
• Age-related differences in physiological responses to exercise are not fully understood.

Purpose of the Study:

• To compare the hormonal, electrolyte, and renal responses to marathon running in young (Y) versus middle-aged (MA) runners.
• To investigate age-related differences in atrial natriuretic factor (ANF) response during prolonged exercise.

Main Methods:

• Measured heart rate (HR), plasma osmolality (OSM), antidiuretic hormone (ADH), aldosterone (ALDO), atrial natriuretic factor (ANF), and plasma renin activity (PRA) in 14 runners (8 Y, 6 MA) before, during (10 km), and after a marathon.
• Assessed renal and urinary parameters.

Main Results:

• Both groups showed increased HR, ALDO, ANF, and PRA at 10 km, with no changes in OSM, Na+, or ADH.
• MA runners exhibited a significantly greater increase in plasma ANF concentrations at 10 km compared to Y runners (104.1 vs. 42.8 pg/ml).
• Post-marathon, OSM, ADH, and Na+ were elevated in both groups, while HR, PRA, and ALDO remained high. ANF decreased from 10 km levels but remained elevated, and HR continued to rise.

Conclusions:

• Middle-aged runners demonstrate an exaggerated ANF response to marathon running, potentially linked to central blood volume expansion.
• These findings highlight age-dependent variations in the regulation of fluid balance and hormonal responses during strenuous endurance exercise.