Background: It is not known whether physical exercise increases daily proteinuria in patients with proteinuric nephropathies, thus accelerating progression of the renal lesion. This study evaluates the acute effects of physical exercise on proteinuria in young adults with immunoglobulin A (IgA) nephropathy.
Methods: Changes induced by intense physical exercise on quantitative and qualitative proteinuria were evaluated in basal conditions and after 10 days of ramipril therapy in 10 patients with IgA nephropathy, normal glomerular filtration rate (GFR), proteinuria between 0.8 and 1.49 g/24 h, and "glomerular" microhematuria before and after the end of a maximal treadmill Bruce test (B-test). The basal study also was performed in 10 age- and sex-matched healthy volunteers.
Results: At rest, GFR averaged 141 +/- 23 mL/min; it increased by 16.3% +/- 3.3% (P < 0.005) and 7.1% +/- 1.6% at 60 and 120 minutes after the B-test, respectively. At rest, GFR-corrected proteinuria averaged protein of 0.76 +/- 0.21 mg/min/100 mL GFR; it increased to 1.55 +/- 0.28 mg/min/100 mL GFR after 60 minutes (P < 0.001) and declined to 0.60 +/- 0.11 mg/min/100 mL GFR at 120 minutes after the end of the B-test. The pattern of urinary proteins remained unchanged, as did microhematuria. Daily proteinuria was not different from the basal value on the day of the B-test. After ramipril therapy, patients showed a reduction in GFR, but no change in daily GFR-corrected proteinuria, pattern of urinary proteins, or hematuria.
Conclusion: The increase in proteinuria after exercise in our patients is significant and is not prevented by ramipril therapy, but lasts less than 120 minutes. Therefore, it cannot modify daily proteinuria. Thus, these data do not support the need to reduce acute physical activity in patients with nonnephrotic renal diseases.