You may have to pay more for your workout gear if President Donald Trump’s latest China tariff plan goes through.

A number of fitness associations and manufacturers of exercise products recently wrote to the Office of the United States Trade Representative saying the proposed fine on Chinese imports could harm the fitness industry and result in much higher prices for consumers, according to public records.

The Sports & Fitness Industry Association (SFIA), a trade organization that represents various companies, wrote in a series of comments that the tariffs could create an additional $7 billion in additional costs for U.S. purchasers of exercise and sports gear. Those increased costs, the SFIA says, could cause some families to abandon activities like youth sports.

Fitbit, producer of the popular fitness tracker, wrote that a tariff on its devices—which are assembled in China—would “impose immediate and substantial costs that could compromise Fitbit’s ability to compete in the market for wearable devices in both the consumer and healthcare sectors.”

The company goes on to argue that foreign manufacturers of fitness trackers would be able to sell their goods at a much lower cost, thereby endangering American companies like Fitbit. Fossil, a watch company, similarly expressed concerns about the tariff’s effects on fitness trackers.

In one letter, the SFIA argues that the tariffs could endanger Everlast Sports, which produces its boxing and MMA gear in China. “Finding alternative sources of production will prove to be a monumental task because, as indicated above, there is very little, if any, capacity to produce these products outside of China,” the SFIA, writing on behalf of Everlast, states.

Randy Hetrick, creator of the TRX suspension trainer, also urged the Administration to halt the tariffs, which he said would result in “higher costs for our products for tens of thousands of independent fitness professionals and their clients, and will negatively impact small business owners and entrepreneurs throughout the United States.”

Not too sure what’s going on? Here’s a quick crash course.

Even before becoming president, Trump complained of U.S.-China trade policies, and has fought to cut the trade deficit between the two countries. He’s already imposed tariffs—or a tax—on goods around the world, including some directly aimed at China.

In May, Trump proposed increasing the existing tariffs and implementing a new 25 percent one on certain goods—that’s what has the fitness industry worried. The tariffs are, in part, designed to encourage consumers to buy American-made products, since it would raise the price of foreign goods.

At the end of June, the U.S. and China agreed to a tentative truce while the two sides discuss alternative measures. But there have been truces between the two sides before, which have broken down and resulted in tariffs on both sides.