Plasma volume and renal function during and after ultramarathon running.

Area of Science:

• Exercise Physiology
• Renal Physiology
• Sports Medicine

Background:

• Understanding physiological adaptations to endurance exercise is crucial.
• Plasma volume regulation and kidney function are key aspects of exercise response.
• Previous research has not fully elucidated post-ultramarathon changes in plasma volume and renal parameters.

Purpose of the Study:

• To investigate changes in plasma volume and renal function following a 56 km footrace.
• To determine the factors contributing to plasma volume expansion post-exercise.
• To assess the impact of exercise on creatinine clearance and identify potential mechanisms.

Main Methods:

• Studied eight subjects for 3 days before and 6 days after a 56 km footrace.
• Monitored plasma volume, creatinine clearance, urine flow, and urine sodium excretion.
• Measured serum enzyme activities, C-reactive protein, serum uric acid, and plasma creatinine.

Main Results:

• Plasma volume increased significantly in the 3 days post-race, driven by albumin influx and increased plasma sodium.
• Creatinine clearance increased after the race and remained elevated for 48 hours.
• Elevated serum enzyme activities and other markers indicated muscle damage.

Conclusions:

• Persistent post-exercise plasma volume expansion is initiated by albumin influx and increased plasma sodium, with reduced urine sodium excretion contributing.
• Post-race changes in serum constituents must be interpreted considering plasma volume alterations.
• Increased creatinine clearance post-running suggests enhanced glomerular filtration rate, possibly due to muscle damage products.