A six-month contract might require a one-month notice period, she said, so unless notice was given a month before the six months was up, the contract would run for at least seven. "You could be stuck paying for a membership for longer than you thought. It is often hidden in the fine print."
Wilson said roll-over contracts were unfair and favoured gym owners over consumers, who had to jump through extra hoops to end an expired contract.
Sarah Goffe, who worked as a gym general manager for eight years, mainly in Wellington, said it was common for salespeople to be told not to let people take gym contracts away to read before they signed them.
"They say something like, 'oh that's just guff, don't worry about it'. Usually at that time they've been on a big tour of the gym and when they get to the contract, it's quite rushed. But usually the contracts are quite locked."
She said she had seen countless people caught out. "When they want to cancel, they'll be told they can't and the salesperson will come out and say 'as per the contract' ... "
She said customers were better to seek out gyms that offered month-by-month contracts or to pay in a lump sum. "Gyms don't like it if you pay a lump sum because they would rather you go on a contract that rolls over at the end of the term."
Marie Smith was forced to pay $20 a week to two gyms in Australia for three months when she couldn't get out of a contract.
"We had to move to the other side of town so I looked into cancelling but the fee was the entire amount left to pay on the contract, and some, so I transferred to a branch a fraction closer to my new place - but because it was a franchise I had to pay the joining fee again. Then a no-contract gym opened near my home so I looked into cancelling again and it was still going to be a fortune so I cut my losses and paid for two gyms for three months."
She said she had since joined Jetts because it did not lock her into a contract. The Canstar survey found Jetts gyms rated best for customer satisfaction, followed by Les Mills.
Fitness NZ chief executive Richard Beddie said people not reading their contracts was more of a comment about the public than gyms.
He said people should keep a copy of their contracts so they could check what they needed to do when the time came to cancel. "Most gyms don't do the hard sell. They're really aware that it's short-sighted and of little benefit to the club."
Canstar New Zealand general manager Derek Bonnar said: "We recommend that anyone entering into a contract with a gym should - before signing up - invest the time to understand the terms of the contract as it is a legally binding document. It is pleasing that nearly three-quarters of those in the survey are doing just that."