Every runner knows the importance of a quality pair of shoes, replaced when they show signs of wear. But not all shoes are created equal. Some shoes are bad for you.

Researchers wanted to find out the effects of running shoes on the runner’s joints. They took 68 healthy female runners and observed their running both barefoot and with a standardized running shoe. “They concluded that running shoes exerted more stress on these joints [knees, hips, and ankles] compared to running barefoot or walking in high-heeled shoes.” They were able to confirm that modern running shoes do give a lot of protection to the foot itself.

However, don’t toss the trainers just yet. The “standardized running shoe” was a Brooks Adrenaline, which researchers selected “for its neutral classification and design characteristics typical of most running footwear.” They concede that “more cushioned or motion control footwear may have been more optimally suited for the foot characteristics of a portion of the study population.” In other words, these shoes were not necessarily the best shoes for the runners, and they did not have any of the proprietary technology that several major shoe companies tout.

The bottom line is this: if you are serious about exercise, you are allowed to be serious about your workout shoes. Go ahead and let an expert fit you properly. Look at the features and technology in the shoe, albeit with a skeptical eye. Don’t buy shoes that don’t fit right, or that aren’t comfortable for your activity (yes, I do some running and jumping in the store when trying on athletic shoes and I don’t feel silly about it). And don’t let the shoe give you an excuse to lapse into bad form, such as heel strikes or bad knee positioning.