Fitness expert and former Olympian Les Mills has died at the age of 91, his family has said.

The New Zealander first opened a gym in Auckland with his late wife Colleen in 1968, and it later became a nationwide chain.

The Les Mills International brand is now known around the world for choreographed workouts set to music, like Body Pump and Body Combat.

Mills, who competed in shot putt and discus at four Olympic Games, later served as mayor of Auckland.

Mills’ son Phillip, who set up Les Mills International with partner Jackie on the back of his parents’ gyms, said he “achieved a huge amount in his life”.

He added: “And the common thread throughout – whether in fitness, politics or family life – was that he always wanted to help others.

“Dad was immensely strong, driven, and always cared deeply for the less advantaged.”

He said that his father’s “spirit lives on in gym workouts around the world, continuing to help people fall in love with fitness”.

Mills won five Commonwealth Games medals, including discus gold in Kingston, Jamaica, in 1966.