Inclusion Criteria:  Up to 40 healthy volunteers, physically trained test subjects. must be able to perform a workout at 80% of maximum heart rate for 60 minutes according to Nes et al. [1], OR perform a workout that causes a dehydration of more than 1.5% of total body weight.  Exclusion Criteria:  Hypersensitivity to sulfonamide or thiazide diuretics. Acid/base imbalance Electrolyte imbalance Metabolic alkalosis Diarrhea Hypotension or orthostatic hypotension Prostatic hypertrophy, urethral stricture, urinary retention Pregnancy or breast feeding Allergy to medical adhesive or gel. Any planned medical examination during the intervention period.