In summary a total of 50 students wore a weight west. Half of the students wore a 10 kg weight vest and half of the students wore a 1 kg weight vest. The study lasted for four hours. The students were only allowed to sit a maximum of 10 minutes during each hour. No significant difference was observed in urine flow rate. Surprisingly however, the investigators found that the students who wore a 10 kg weight vest excreted more electrolytes than those wearing a 1 kg weight vest. In the group free from treatment (see below) only consisted of 13 subjects and the investigators were therefore not able to obtain significant results (p=0,088). The investigators believe that with a larger study population and better matched controls the investigators will reach significant results.