Changes in the concentrations of urinary proteins after physical exercise.

The influence of physical exercise on the urinary excretion of proteins was examined in 17 male high school baseball players. Their urine was collected before and after exercise to determine the concentrations of total protein, albumin, beta 2-microglobulin and creatinine along with the activity of N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30). Concentrations of total protein, albumin, beta 2-microglobulin and creatinine increased significantly (p less than 0.01) after exercise, while N-acetyl-beta-D-glucosaminidase activity did not increase. Similar results were obtained when the concentrations of these urinary components were calculated on the basis of a urinary density of 1.024, and when they were expressed relative to the amount of creatinine. Positive correlations were seen among total protein, albumin, beta 2-microglobulin and creatinine concentrations, but not between the beta 2-microglobulin concentration and N-acetyl-beta-D-glucosaminidase activity. Isoenzyme activities of N-acetyl-beta-D-glucosaminidase in the urine were determined by electrophoresis on cellulose acetate plates. After exercise, the A-form increased slightly, and the B-form decreased slightly, but these changes were not statistically significant.