The indoor study phase lasts ca. 2 hours, where the volunteers will be analysed during running on a tread mill with both, the IPANEMA system and common medical monitoring procedures. The evaluations of identical physiological parameters obtained by use of stationary diagnostic equipment, the ergospirometric device PowerCube Ergo, BIS measurement system Xitron Hydra 4200, infra-red camera VarioCam®hr-basic and standard medical ECG measurements are used as reference values. Two hours before the start and during the entire training phase, the experimental group is restricted to food and liquid intake in opposite to control group. These experimental conditions purpose to clarify several physiological effects of dehydration during sportive activities. The outdoor- and climate chamber- investigations do not prescribe the liquid deprivation.