Alexander Stahn 1,2, Elmarie Terblanche 3 and Günther Strobel 1 1 Institute of Sports Medicine, University Hospital Charité, Campus Benjamin Franklin,

Free University of Berlin, Germany 2 Department of Medical Physiology, Faculty of Health Sciences, University of

Stellenbosch, South Africa 3 Department of Sport Science, University of Stellenbosch, South Africa


Heavy exertion and severe bouts of exercise may cause substantial losses of body water. A number of studies have shown that hypohydration of slightly more than 1% of total body weight may already impair physical and mental performance (Cian et al., 2001; Sawka, 1992). Water losses in excess of 3% are regarded as potentially harmful. Extreme fluid losses can even cause failure of the cardiovascular system (Greenleaf, 1992). Hence, an accurate, simple and non-invasive technology to monitor hydration changes is particularly important for maintaining exercise performance, as well as general health.