Objectives: Assessment of the effect of training on Special Aerial Gymnastics Instruments (SAGI) on the urine β-2- microglobulin (β-2M), albumin (ALB), total protein (TP), N-acetyl-β-D-glucosaminidase EC.3.2.1.30 (NAG), expressed as creatinine (Cr) and on the physical fitness of the examined cadets in comparison with the control group. Material and Methods: The study involved 55 cadets aged 20, divided into group A (N = 41) trained on SAGI, and group B (N = 14) – a control group. The urine was collected twice: before the training (BT) and after the training (AT) at the start (training I), during (training II), and after completion of the training program (training III). Urine proteins were assayed with commercially available kits. Results: In group A, results obtained in trainings I, II and III showed a statistically significant increase in β-2M/Cr, NAG/Cr, TP/Cr, ALB/Cr indices in AT compared with the baseline BT values. Similarly in group B, a statistically significant increase in β-2M/Cr, NAG/Cr (trainings I, II), TP/Cr, AT compared with the baseline BT values in trainings I, II, and III was noted. Comparison of both groups showed a higher value of the post-exercise proteinuria in group B than in group A. In group A, a significant correlation between TP/Cr vs. ALB/Cr, NAG/Cr vs. TP/Cr, β-2M/Cr vs. TP/Cr, i.e., r = 0.62 at p < 0.001; r = 0.33 at p = 0.03; r = 0.60 at p < 0.001, and r = 0.52 at p < 0.001, respectively, was observed in group A, training III, AT. Conclusions: Assayed urine proteins depend on the intensity of physical exercise, the type of exercise, and the level of physical fitness.