The effect of exercise intensity on hematuria in healthy male runners

The purpose of this study were: (1) to establish the prevalence of exercise -induced hematuria in a group of otherwise healthy male runners (n = 70), a nd (2) to investigate the role of exercise intensity in those runners who e xhibited exercise-related hematuria (n = 10) by evaluating the effect of ru nning and cycling at high and low intensities. The identified and recruited subjects participated in four different exercise protocols: (1) a 60-min t readmill run (RUN) at 90% of anaerobic threshold (Th,,), (2) a 60-min leg c ycle ergometer ride (BIKE) at 90% of Th-ae, (3) a 3 x 400-m sprint (SPRINT) , each followed by 4 min of rest or light walking, and (4) 3 x 60-Wingate l eg cycle ergometry tests, each followed by 4 min of rest or light cycling. The study employed a 3 x 4 (time by protocol) within-subjects design and de pendent variables were measured before exercise, 4 min after, and 1 h after exercise, and included measurements of hematuria, proteinuria, urinary pH, serum haptoglobin concentration, serum creatine phosphokinase activity, pl asma lactate concentration, and hemoglobin. The 400-m sprint at maximal eff ort significantly increased both hematuria and proteinuria (P < 0.01). Post -exercise hematuria for the SPRINT protocol was significantly different tha n that for the BIKE(P < 0.01) and RUN (P < 0.01) protocols. Due to the sign ificant increase in hematuria and proteinuria following the SPRINT protocol , it was concluded that exercise-related changes in renal function were ass ociated with weightbearing exercise intensity rather than non-weight-bearin g exercise duration.