Turned 68 in January. Running since a soph in HS (shitty!). In the 80's ran a lot of 90+ weeks with a lot of hills...ran all my miles hard. Nagging injuries started popping up in the late 90's, mileage dropped off along with effort and pace.
Bought a treadmill and 2010 and it's been great for getting back into it. Soft surface, controlled pace,up-hill workouts w/o the downhill pounding. Now I run about 80% of my miles on the TM, and the rest on gravel or paved roads. On roads, I never run anything shorter at pace than 600's. On the TM, I do a lot of 1K repeats at 92%-95% Max HR, as well as 30-40 minute tempos in the 7:45
pace range. Also do cadence work on the TM with a metronome. Injuries have been kept at a minimum since I got the TM, and am now averaging about 40-45 running miles a week. Take off one or 2 days a month. This weekend I ran my 1st race of the year and broke 22:00 in a local 5K under rainy/windy conditions so I'm pretty pleased about that. I understand that 22:00 is a HJ time to some on this board, but it's one Hell of an effort for an old fart like myself (pats self on back).