Last week, we talked about a recent drop in basketball shoe sales and how could affect LeBron James' $1 billion Nike deal, but it's not just hoops shoes that are struggling right now.

Reporting for Forbes, NPD Group's Matt Powell writes that he's never seen a downturn in performance sneaker sales like the one that's happening now. According to Powell, there isn't even one major performance shoe category that's flourishing. 

Powell notes that performance running shoe sales took a major hit in 2013 and haven't fully recovered since, while lifestyle (or retro) runners make up 30 percent of current running shoe sales in comparison to just 20 percent during this time last year. 

He also says that much of adidas' recent success can be attributed to non-performance sneakers, which is partially true, however the brand itself has cited the Ultra Boost performance runner as one of the biggest reasons it's been able to turn things around in the U.S.

As for the future, Powell says that this trend allows brands who don't have experience making sneakers to get involved with something they don't have any business doing, which would result in more "non-technical brands creating fun fashion sneakers" and "confusion and noise within the marketplace"—something we've already started seeing with brands like AldoSteve Madden, and Zara ripping off of Yeezy Boosts.