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Kidney function during exercise in healthy and diseased humans. An update
J R Poortmans1, J Vanderstraeten
1Institut Supérieur d'Education Physique et de Kinésithérapie, Université Libre de Bruxelles, Belgium.
Sports Medicine (Auckland, N.Z.)
|December 1, 1994
Summary
Exercise significantly impacts kidney function, altering filtration and protein excretion. Post-exercise protein in urine is linked to exercise intensity, not duration, and resolves within hours.
Area of Science:
- Nephrology
- Exercise Physiology
- Renal Physiology
Background:
- Exercise profoundly alters renal hemodynamics and protein excretion.
- Glomerular filtration is governed by pressure gradients, and filtration fraction can double during maximal exercise.
- Tubular processes and excretion rates are modified by physical activity.
Purpose of the Study:
- To investigate the effects of exercise on renal hemodynamics, tubular transport, and protein excretion.
- To understand the mechanisms behind exercise-induced changes in kidney function.
- To examine factors influencing post-exercise proteinuria.
Main Methods:
- Analysis of renal hemodynamics, including plasma flow and filtration fraction.
- Assessment of tubular transport mechanisms for lactate, urea, and uric acid.
- Measurement of post-exercise proteinuria and its relationship to exercise intensity, duration, and patient characteristics.
Main Results:
- Maximal exercise can double the filtration fraction despite reduced renal plasma flow.
- Renal lactate excretion is limited, with transport mechanisms saturating during severe exercise.
- Urea reabsorption increases during prolonged exercise, potentially mitigating dehydration.
- Uric acid transport does not appear to saturate.
- Post-exercise proteinuria correlates with exercise intensity, not duration, and resolves within approximately 1 hour.
- Increased protein clearance suggests heightened glomerular permeability and reduced tubular reabsorption.
- Exercise may decrease the glomerular electrostatic barrier, facilitating macromolecule transfer.
- Post-exercise proteinuria is age-dependent and less pronounced in heart and kidney transplant recipients compared to healthy individuals.
- Exhaustive exercise does not exacerbate kidney dysfunction in diabetic patients beyond existing levels.
Conclusions:
- Exercise induces significant, transient changes in renal function, including altered filtration and protein excretion.
- The intensity of exercise is a key determinant of post-exercise proteinuria.
- Kidney response to exercise is modulated by factors such as age and underlying health conditions like diabetes and transplant status.