Originally Posted by BengalCat

Seventy-year-old riders that do consecutive or regular hard days, (4-5 days a week) and recover adequately, exist. They are the exceptions rather than the rule.

After many years off the bike, I picked it up again at age 64. I steadily increased my performance steadily up until I reached 70. From 70 on it has been all downhill in every way since then despite continuing quality effort rides. Now as I approach 74 I've lost 60-65 watts of power in the past three and one-half years.