BERLIN, Germany — A German court has rejected an attempt by Adidas to stop its smaller rival Puma from selling a new line of shoes with light-weight, bouncy soles similar to its popular "Boost" brand.

The two sportswear companies have a fierce rivalry that dates back to their foundation in the late 1940s after a falling out between brothers Adi and Rudi Dassler in the southern German town of Herzogenaurach.

The sporting goods industry has seen a big rise in patent disputes in recent years as the biggest players try to differentiate their products with features aimed at improving sporting performance rather than just looking good at the gym.

Both Adidas and Puma worked with German chemicals firm BASF on a new foam polyurethane that BASF says is as elastic as rubber, but lighter, providing a springy and cushioning sole that is ideal for running shoes.

However, BASF struck an exclusive deal with Adidas on the technology in 2011, allowing the bigger company to launch its new line of "Boost" shoes in 2013. It sold 10 million pairs in the running category alone in 2015.

That forced Puma to look for a new partner for the foam and it teamed up with US company Huntsman Corp in 2014, launching its "NRGY" line last year. The shoes sell for about $100 and upwards a pair, still well below the price for most "Boost" ranges.

Adidas sought an injunction to stop the sale of "NRGY", but lost the case at the Duesseldorf regional court on Tuesday.

"Puma tried to show Adidas with this case that even though we are smaller, we will not give in that easily. We will fight for our rights," Neil Narriman, Puma head of intellectual property, told Reuters.

Narriman said Puma had held back from launching many versions of "NRGY" due to the case but would now promote the rival to "Boost" more aggressively.

An Adidas spokeswoman said the firm did not agree with the court decision and would review its next steps.

"We will continue to vigorously protect our rights and will continue to take action in case of infringements," she said.

Separate proceedings that Puma brought against Adidas, accusing its bigger rival of profiting from its earlier work with BASF, are still ongoing. Adidas denies the Puma charge, saying it worked in parallel to Puma with BASF.

By Emma Thomasson.