EXERCISE-INDUCED SWEAT NITROGEN-EXCRETION - EVALUATION OF A REGIONAL COLLECTION METHOD USING GAUZE PADS

The exercise-induced sweat nitrogen excretion was investigated during a 45-minute run at moderate intensity on a treadmill. Sweat was collec ted with a regional collection technique using gauze pads and compared with the whole-body wash-down (WBW) method. In the regional collectio n, sweat was sampled from the upper back (UB), lower back (LB), abdome n (AB), and thigh (TH). Additionally, the relation of sweat urea, ammo nia, and amino acids was investigated with the regional collection met hod during a second 45-minute run. Independent of the sweat collection method, a significant and positive correlation was found between swea t rate and the excretion rate of the largest nitrogen fraction urea, s uggesting that the sweating response to exercise might be one of the m ost important factors determining absolute sweat nitrogen losses. The urea nitrogen excretion was nearly 140 mg.h(-1) in the second run, rep resenting the largest nitrogen fraction. Ammonia nitrogen and amino ac id-derived nitrogen rate were approximately 30 mg.h(-1) and 10 mg.h(-1 ), respectively. The comparison of the sampling methods during the fir st run revealed that the urea nitrogen rate was significantly higher, but the ammonia nitrogen rate significantly lower in the WBW. After su mming urea and ammonia nitrogen, no significant difference between the methods was observed anymore, except for UB. It is concluded that the regional collection method using gauze pads is a valuable approach to measure exercise-induced sweat nitrogen losses during moderate runnin g exercise.