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Renal function and plasma volume following ultramarathon cycling
G Neumayr1, R Pfister, H Hoertnagl
1Institute of Sports Medicine, University Clinics of Innsbruck, Innsbruck, Austria. guenther.neumayr@sb-bruneck.it
International Journal of Sports Medicine
|January 12, 2005
Summary
Ultraendurance cycling minimally impacts renal function in elite athletes, with temporary changes. Plasma volume shows a pronounced, temporary increase, indicating haemodilution post-exercise.
Area of Science:
- Sports Medicine
- Renal Physiology
- Exercise Physiology
Background:
- Marathon cycling shows minimal renal effects in recreational athletes.
- Limited data exists on extreme ultramarathon cycling impacts in highly trained athletes.
Purpose of the Study:
- To assess renal and hematological effects of ultraendurance cycling.
- To evaluate these effects in elite ultramarathon cyclists.
Main Methods:
- Investigated creatinine, urea, hemoglobin, hematocrit, and plasma volume in 16 male ultramarathon cyclists.
- Measurements taken during the Race Across the Alps (525 km, 12,600 m altitude gain).
Main Results:
- Serum creatinine, urea, and uric acid increased significantly during the race but normalized within 24 hours.
- Creatinine clearance decreased by 25%; reduced renal perfusion indicated by low fractional sodium and uric acid excretion.
- Hematocrit declined, with plasma volume increasing by 22%, indicating marked hemodilution.
- Higher training volume correlated with smaller increases in serum creatinine.
Conclusions:
- Ultraendurance cycling causes minimal, temporary renal function changes in elite athletes.
- Plasma volume expansion and hemodilution are significant post-exercise effects.
- High-volume training may attenuate some physiological responses to ultramarathon cycling.