Recent work in the area of sport expertise suggests that practice patterns can also play a critical role in maintaining athletic performance. This article examines the contribution of both physiological changes and practice patterns to swimming performances of master-, international-, junior-national-, and varsity-level swimmers. A comparison of the practice patterns of these groups suggests that master athletes spend significantly less time per week training for competition, and their training focus is on endurance, not strength. Younger swimmers train for endurance, strength, speed, and power. The authors suggest that these differences might be partly responsible for age-related performance changes. Performance changes for semilongitudinal and cross-sectional samples are characterized by significant quadratic beta weight, indicating increasing declines in performance starting at around 60 years of age. These data are discussed with respect to the role that practice plays in explaining performance change...