BACKGROUND We describe a runner who completed a self-paced marathon (42.195 km) in a climate chamber with a temperature difference of 100°C, starting at an ambient temperature (Tambient) of -45°C and finishing at an Tambient of +55°C. METHODS Tambient was set at -45°C at the start, and was steadily increased at a rate of 1°C at 4.5-minute intervals to +55°C. Before the start, after every 10.5...