Eder Jofre has that famous video of him destroying the bag with combos at an advanced age. The documentary 'Joe, Tommorrow' shows Joe Tatsuyoshi out training his pro boxer sons despite being twice their age.
Jack "Kid" Berg skipped 20 minutes every day in his late seventies. Brian London never drank or smoked and was running at least 2 miles a day until a few weeks before his death.
I saw a recent(ish) interview of him on YouTube that was wishing the last year and a half or so and he looked good. Interviewer even commented that he looked in shape.
You bet. This is from 2018. You sometimes see elite athletes who reached fitness levels that we’ll never know go to pot…badly. Perhaps due in part to the trappings but also maybe also due to an accumulated aversion to any type of exercise after years of spartan training. This man used to fight at 126 lbs? He’s just 5’ 4 1/2” so hard to gage but I’d guess at least 210 lb or more probably. https://www.pressreader.com/uk/daily-star/20180309/281960313263836
Based on his Superstars performances in the masters division, Joe Frazier performed at least as well in the weightlifting event as an older man as he had during his prime. Maybe he used weights to keep in trim as he aged, or maybe he stayed in shape in other ways.