N=2 anecdotes:
A friend of mine, long-time bike racer, died at the age of 61. He needed a heart transplant and decided to pull the plug (long story). I knew him for 30 years and would say that he was overtrained 90% of the time.
Another friend died at the age of 72 from complications during heart surgery. He was a lifelong athlete, but got really serious about endurance athletics in his 60s (RAAM, etc.).
Don't overdo it.
A friend of mine, long-time bike racer, died at the age of 61. He needed a heart transplant and decided to pull the plug (long story). I knew him for 30 years and would say that he was overtrained 90% of the time.
Another friend died at the age of 72 from complications during heart surgery. He was a lifelong athlete, but got really serious about endurance athletics in his 60s (RAAM, etc.).
Don't overdo it.