I came across this great article about a woman who made her bodybuilding debut at the age of 57. 

When she reached her early 50s, Bonnie Ave had a bone-density test done. At 56, she had a follow-up test, which revealed she was at risk for osteoporosis.

One solution? Begin regular weight training.

“My doctor said my numbers were not good,” Ave recalled. “So I decided to go into bodybuilding.”