By Nathalie Voit

Popular fitness apparel brand Nike sued Lululemon for patent infringement over the use of the leggings maker’s Mirror fitness technology and related mobile applications.

In a complaint filed on Jan. 5 in the Southern District Court of New York, Nike accused its younger rival of infringing on six of its fitness equipment patents by selling Mirror Home Gym, the interactive at-home fitness device equipped with access to thousands of workouts.

According to Nike, Mirror and its applications infringe on the sneaker giant’s proprietary technology through the use of applications on a device for collecting fitness data, logging guided workouts, monitoring heart rate levels, and measuring individual performance metrics, among other exercise-related functions, according to The Wall Street Journal.

Nike said it notified Lululemon on Nov. 3 of the alleged infringement but that the yoga maker dismissed the company’s claims.

In response to the letter, a spokeswoman for Lululemon said the company didn’t believe the use of the Mirror platform or its apps constituted patent infringement by Lululemon.

“The patents in question are overly broad and invalid. We are confident in our position and look forward to defending it in court,” the representative said in a statement, the Journal reported.

Nike is seeking triple damages for the purported infringement, NBC News said.

Lululemon acquired Mirror for $500 million in July 2020 amid a rush to capitalize on the at-home workout trend brought on by the COVID-19 pandemic. The upscale activewear brand is also embroiled in another legal battle with connected fitness equipment company Peloton.

In November, the company filed a suit against Peloton, accusing the home-exercise gym equipment maker of infringing on its patented sports bras and leggings designs.

Peloton sought a court declaration stating it has not infringed on any patents in response, CNBC said.

According to Lululemon’s website, a basic Mirror package costs $1,195, on sale from its original $1,495 price tag. Packages range as high as $2,045.