When people say swimming is for people of all ages, they mean it. At least Japan's Mieko Nagaoka does.

Over the weekend, the 100-year-old Masters swimmer became the first centenarian to finish a 1,500-meter competition in a 25-meter pool. She competed alone at a Japan Masters Swimming Association event, in a swim for the 100- to 104-year age bracket. She performed the backstroke and accomplished her feat in just less than one hour, 16 minutes.

Her time likely will be sent to the Guinness Book of World Records.

So far, this is the apex of a 20-year swimming career. Nagaoka began the sport in her 80s to help with a knee problem and holds several records. She trains for two-hour sessions, four times a week. Read More