(CNN) She may be nearing 101 years old, but Mieko Nagaoka isn't slowing down -- at least in the pool.

This weekend saw her add to an impressive career, becoming the first person over 100 to complete a 1,500-meter swim in a 25-meter pool.

Nagaoka, the only competitor for the race in the women's 100- to 104-year age bracket, completed the swim -- which she did backstroke -- 1 hour, 15 minutes and 54 seconds, setting a world record in the process.

The feat was achieved at a Japan Masters Swimming Association event in Matsuyama, Ehime prefecture. Her official time is expected to be sent to the Guinness Book of World Records for ratification.

The centenarian, who only took up swimming in her eighties while undergoing aquatherapy for a knee problem, has ratcheted a slew of records in her 20 years in the sport, with Saturday's achievement going alongside age class records for everything from the 100m, 200m and 800m freestyle, alongside the 50m, 100m and 200m backstroke.

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