Japan has one of the oldest populations in the world, but some of the country’s elderly aren’t slowing down. Mieko Nagaoka first started swimming in her 80s to help recover from a knee injury sustained while practicing Noh, a traditional Japanese theatre. When she was 100, Nagaoka published her book entitled: "I'm 100 years old and the world's best active swimmer", before going on to set the first world record for her age group, swimming 1,500m in a 25m pool. At 105 years old, she still enters Masters competitions and currently holds 18 world records. (BBC News)