I just turned to 70 last week, and I have chronic back issues. I have averaged 5000 miles per year for the past 10 years. This past spring I had a bout of acute prostatitis and was off the bikes for awhile, and limited miles for 4 months. When returning to riding in May, I realized I needed to start off relatively slow and easy. Even when I considered myself totally recovered, I still had lost some stamina and strength. Now, mid September, and I know I have less stamina, but I believe my leg strength is back. I need 800 more miles to get my 5000 for '22, then, I think I will start doing some intervals to work on stamina. Those I do indoors, easier to control the time, cadence and intensity without the need to steer and pay attention to the surroundings