SAN DIEGO -- A San Diego law firm says dozens of people hoping to tone up with the help of special footwear were dealt serious injuries by the shoes.

In commercials, Skechers claims its "Shape-up" shoes are themselves a workout. One ad states: "With Shape-ups, you can finally get in shape without going to the gym."

The company touts a patented design -- including a rolling bottom -- that changes the way a person walks. The design utilizes different muscles in the body and firms them up.

San Diego native Lisa Baseet, who now lives in Ventura, saw the ads and bought a pair a year and a half ago. She said she slightly twisted her ankle twice. After nine months of wearing the shoes, she suffered a serious injury.

"I twisted my ankle and heard something snap, and I went down," said Baseet.

Baseet said she tore tendons and ligaments in her left ankle.

Baseet is one of 37 people who bought Shape-ups or Tone-ups shoes named in a class-action lawsuit filed by local law firm Estey and Bomberger. In addition to claims of negligence and fraud, all customers in the suit cited serious injuries, from torn cartilage to hip fractures.

Attorney Mike Bomberger said some injuries were caused by a fall, while others were hurt after wearing the shoes for months.

"Man has been walking the same way for many years, and this changes the way you walk. It's not a surprise people are going to have problems," said Bomberger.

Bomberger said what is most disturbing is what Skechers has not revealed.

"We aren't aware of any safety tests Skechers has done for these shoes and that's a real problem … because the public, when they purchase the product, has a right to assume the product is safe," he said.

Industry experts believe the federal government could soon take a close look at Skechers.

Recently, Reebok was fined $25 million by the Federal Trade Commission for making false claims that its toning shoes could strengthen legs and backsides.

Baseet said she wants the Skecher shoes off the market before others get hurt.

"I'm disgusted. I paid so much money to tone up and now I need surgery," said Baseet.

Skechers did not respond to 10News' calls.

In a previous published statement, the company said: "Millions of people wear Shape-ups without experiencing (serious injuries)."

While there have been several individual lawsuits filed against Skechers, the just-filed lawsuit is the largest class-action suit filed so far.