"Estimated Age Effects in Athletic Events and Chess," Experimental Aging Research, 2007.Paper: pdf file
Rates of decline are estimated using record bests by age for chess and for various track and field, road running, and swimming events. Using a fairly flexible functional form, the estimates show linear percent decline between age 35 and about age 70 and then quadratic decline after that. Chess shows much less decline than the physical activities. Rates of decline are generally larger for the longer distances, and for swimming they are larger for women than for men. An advantage of using best-performance records to estimate rates of decline is that the records are generally based on very large samples. In addition, the age range is large. In this study the age range is 35 to 100 for swimming, 35 to 98 for track and field and running, and 35 to 94 for chess. The estimates also do not suffer from traditional forms of selection bias.
This is the second paper I did on aging. For the complete list of papers see Papers on Aging.