Abstract

A 55 year old runner covered 160 km within a 20 hour period. His speed averaged 8.16 km/h, at an estimated 59.1% of maximum oxygen intake. After the first four hours of running, one of five fluids was taken in rotation every twelve minutes. Volumes ingested whe heart rate for the final four hours (125/min) was not increased relative to oxygen consumption for this portion of the run. Constancy of heart rate, continued urine production and formal fluid balance calculations all indicate that hydration was well maintained over the run. Caloric intake averaged 480 kcal/h (2.01 MJH), being greatest fro the ice-creas/syrup mixture; the energy deficit (56/KA/H, 235 kJ/h) was small during that part of the run in which food was provided.