At our age we're wise enough to know how to avoid the need to run 40 yards at high speed! As I near 60 I'm still in great shape. I can ride a century in less time than it took me in my twenties, but I'm plain heavier than I used to be. Of course, my waist and chest we're 32 and 40 inches then whereas now they're 36 and 44. Extra weight kills acceleration.