In fact, given a full year, I think I could be in the best shape of my life. Unemployed for 4 1/2 months at 28, I went to the gym twice a day, cooked nothing but good food, took college classes, looked for a job. Best shape of my life. My body wouldn't respond like it did then but, with a full year of nothing on my plate but getting in the best shape possible, I think 54 y/o me would be better than 28 y/o me. Assuming, of course, my body didn't break during the process.
So, yeah, I think it's entirely possible a 53 y/o can be in better shape than when he was 34. Probably happens more often than you think.
Go to college, do a couple of sets of curls/extensions every couple of days, eat what you want, party it up, still in good shape.
Graduate, get married, work on career, maintain college eating/workout habits, get a little flabby over the next 15 years.
Suddenly realize "****, I'm not 22. My metabolism changed. I gotta eat better and get a few legit workouts in."
I wouldn't be surprised if mid-30s was the time in life when you're in your worst shape. Unless, of course, you said "**** it" and never worked out again. Plenty of fatties in the US who took that route.