The aim of this study was to measure the change in running performance in a runner from age 27–64 years. During this time the runner had a history of high-volume training and racing. The change in his average running speed over 10-, 21.1-, 42.2-, and 90-km races was compared with the changes in the age-group records for each distance. He trained an average of 4,051 ± 1,762 km/year and ran 16,604 km during races. His training load reached a peak of 7,596 km/year at the age of 33. His rate of decline in running performance was higher than the expected age decline at 47 years for 10-km, 47 years for 21.1-km, 40 years for the 42.2-km, and 48 years for 90-km races. Decreases in performance with increasing age could be explained by reduced training volume, or, alternatively, high volumes of training and racing might accelerate the normal age-related decrements in running performance.