For me, the biggest limitation on my training as a result of advanced age is recovery time. (Injury is a close second, but that's a topic for another time.)
Does anyone have any tips on how to speed recovery so us older runners can squeeze more quality workouts into our training?
After a workout, I mix about 60g of whey protein with about a half liter of Gatorade. It helps me get through the rest of the day without a nap. Whether it actually helps recovery is a subjective yes for me, so I'll keep on doing it.