Urinalyses and body mass changes during an ultra-distance endurance event : the Simpson Desert cycle challenge

Hypohydration during high intensity and I or prolonged exercise in thermally stressful environments may lead to decreases in physical performance, thermoregulatory ability and cardiovascular function (1). Athletes competing in thermally stressful environments are advised to observe sweat losses and measure both fluid intake and body mass in order to monitor fluid losses. However, these techniques may not be accurate unless all food intake, fluid intake, sweat loss, respiratory fluid loss, and faeces losses are accurately monitored (2). It has also recently been suggested that urinalysis is a valid and non-invasive screening tool to monitor hydration status in athletes (2). The purpose of the present study was to describe the body mass and urine changes that occurred over a five-day, 580 km multi-stage cycling race (Simpson Desert Cycle Challenge - SDCC) across Australia's Simpson Desert in ambient temperatures ranging from 16-47 °c.