Sort of.  I ran a lot in high school.  Ran some more in the Army.  Ran intermittently through the years since then.  Took up running again 4 years ago.  I can still run, thank God.  But I have nowhere near the stamina, strength, and endurance I once had.  I’m capable of improving, but it’s literally a constant struggle.  If I take even a week off, it will set me back a minimum of six weeks.  If I eat more than a little bit of junk food, I won’t improve and may even backslide if I eat too much.  I’m more or less at a point of stasis now where I improve a little bit then lose it.  I feel great physically, but I have reconciled myself with the fact that I have more or less peaked out and as the years go by my ability to run will steadily erode.  The only saving grace is that my joints are still in great shape.  I run about 25 miles a week and have no issues with knees, ankles, or back.