In 1976, Muhammad Ali fought Japanese wrestler Antonio Inoki in Japan. In 2017, Floyd Mayweather, at 40 years old, came out of retirement to fight MMA star Connor McGregor. Mayweather won by TKO after wearing down McGregor in a fight that drew 4.3 million pay-per-view buys with a total revenue of $600 million.

The Texas Department of Licensing and Regulation states that "contestants who are age 36 or older, must submit a report of favorable physical testing."