I see old dudes make the "accelerated decline" claim all the time, and I just don't believe the evidence is very strong. Maybe after 70; or maybe not. But the evidence before 70 is pretty weak.
Most old folks (1) aren't training very wisely; (2) have given up on intensity; and have been convinced by their peers that (1) and (2) are a young man's game.
I grant that high level performance, and high level training, is just more difficult as we age. But that's a different claim from accelerated decline.
"Master athletes maintain high physical activity levels and have better health than age-matched non-athletes. World records show accelerated declines after age 70 in swimming, long-distance running and sprint performance. However, less is known about age-related performance declines in the general master athlete population and whether decline rates differ between disciplines and genders. We interrogated a dataset including all track and field athletes of North Rhine from 2001 to 2014 to assess age-related changes in performance. 27,088 results of athletes between 11 and 89 years of age in 12 disciplines were analyzed by regression statistics. The analyses showed an accelerated decline beyond the age of 70 in sprint, middle- and long-distance running, while in throwing and jumping disciplines the performance continued a linear decline. Patterns of decline differed between men and women. The steepest declines were observed in javelin throw and 400 m (women), and in pole vault and 800 m (men). In conclusion, performance declines in aging depend more on the specific profile of requirements than previously assumed."
