This paper uses world records by age in running, swimming, and rowing to estimate a biological frontier of decline rates for both men and women. Decline rates are assumed to be linear in percent terms up to a certain age and then quadratic after that, where the transition age is estimated. The use of world records avoids the possible problem of survivor bias in a sample.
The decline rates are smallest for rowing, followed by swimming and then running. Decline rates for women are roughly the same as those for men for the swimming events. They are slightly larger for the rowing events. They are largest for running. The age at which there is a 50 percent decline from age 30 ranges from 69 to 89, an optimistic result for humans. Ten year decline rates from age 40 to about the mid 60’s are about 10 percent for running and 5 percent for swimming and rowing.