To maintain a normal hydration level and urine production the study subject will continue to replace with fluids during the experiment. The volume of fluids that will be replaced will be equal to the amount of lost urine volume. If for example the study subject loses 100 ml urine he or she will drink of 100 ml water before continuing the experiment. By this method a urine production of approximately 200 ml per hour is maintained which is more than enough to perform all the required urine measurements.