Lululemon Athletica Canada Inc. has launched a lawsuit against exercise equipment company Peloton Interactive Inc., accusing the stationary bicycle and treadmill maker of patent infringement.

In documents filed in a U.S. court on Monday, the Vancouver-based athletic apparel retailer claims Peloton is infringing on multiple design patents and selling 鈥渒nock-off鈥� bras and pants.

The lawsuit comes after Peloton ended a co-branding agreement with Lululemon earlier this year and announced its own private label, Peloton Apparel, in September.

Lululemon alleges Peloton is selling 鈥渃opy-cat products鈥� that closely resemble several of the retailer鈥檚 best-selling designs, including a pair of workout pants and a popular strappy sports bra.

鈥淯nlike innovators such as Lululemon, Peloton did not spend the time, effort and expense to create an original product line,鈥� Lululemon alleged in court documents.

鈥淚nstead, Peloton imitated several of Lululemon鈥檚 innovative designs and sold knock-offs of Lululemon鈥檚 products, claiming them as its own.鈥�

The retailer said it initially sent Peloton a cease-and-desist letter, laying out its concerns with the exercise equipment maker鈥檚 鈥渂latant misappropriation鈥� of Lululemon鈥檚 product designs, according to court documents.

Lululemon said Peloton requested an extension to respond to those allegations, but then used the delay to 鈥渟ecretly prepare its own complaint and pre-empt the lawsuit that Lululemon had so clearly threatened.鈥�

Last week, Peloton sued Lululemon, asking a U.S. court to declare that it has not infringed on Lululemon patents.

鈥淟ululemon鈥檚 allegations lack any merit,鈥� Peloton claimed in documents filed in a New York court.

鈥淓ven a quick comparison of the Lululemon patented designs with the allegedly infringing Peloton products reveals numerous clear and obvious differences that allow the products to be easily distinguished.鈥�

Peloton also claims that the brands of both companies are distinctive and well-recognized 鈥渕aking confusion between products a virtual impossibility.鈥�

But in a series of exhibits filed with a California court, Lululemon alleges several Peloton styles are nearly identical to Lululemon products.

One design the retailer highlighted is its Align pants, a pair of leggings Lululemon called one of its 鈥渁ll-time best-selling products.鈥�

Lululemon alleges a Peloton style is an imitation of the Align pant, with a similar waistband and stitching.

The Canadian retailer said the similarity between Peloton products and Lululemon鈥檚 鈥渋conic designs鈥� is 鈥渓ikely to cause confusion, cause mistake, and to deceive鈥� customers into thinking the Peloton apparel is made in affiliation with Lululemon.

The company alleges Peloton鈥檚 intention is to 鈥渂latantly copy Lululemon鈥檚 proprietary designs and pass off its goods as Lululemon鈥檚 high-quality products to misappropriate the immense goodwill that Lululemon has spent enormous time, effort, and expense to cultivate in the marketplace.鈥�

In an emailed statement, Shannon Higginson, Lululemon general counsel and senior vice-president, said: 鈥淲e are confident in our position and look forward to properly resolving this case through the courts.鈥�

Peloton said it would not comment on active litigation.

鈥擝rett Bundale, The Canadian Press