By Nick Georgandis

As reported earlier this week, Martina Navratilova has announced she will play in the 2014 World Tennis Challenge at Memorial Drive, despite the fact that she is 56 years old and has not played on tour since 2006 when she won the mixed doubles title at Wimbledon at age 49.

This will be Navratilova's second straight year at the World Tennis Challenge. In the past five years, she's also attempted to climb Mount Kilimanjaro and appeared on ABC's Dancing with the Stars reality TV competition.

Navratilova joins a rare breed of athletes who continue to compete past the age of 50. Here's a glance at some of the company she'll be keeping when she once again takes the court in 2014.

• Satchel Paige, baseball: Born in 1906, Paige played in the Negro Leagues for most of his career before debuting in the majors as a "rookie" at age 42. In 1965, at age 59, he was signed by the Kansas City Athletics and notorious owner Charlie Finley. After sitting in a rocking chair in the bullpen before the game, Paige started the game and pitched three scoreless innings.

• Nancy Lieberman, basketball: Navratilova's former trainer and partner, a 50-year-old Lieberman signed a seven-day contract with the WNBA's Detroit Shock and played in a game against the Houston Comets, contributing two assists.

• Gordie Howe, hockey: The legendary Canadian played for the NHL's Hartford Whalers in the 1979-1980 season, during which he turned 51. He played in all 80 regular season games and helped Hartford make the playoffs, and he made the All-Star team, where he played alongside then-19-year-old Wayne Gretzky.