Image: Ohio State University’s Wexner Medical Center

Compression tights are touted as enabling athletes to run faster and farther, while reducing injuries, but a new Nike-funded study—one that appears to have backfired on the clothing manufacturer—suggests these trendy items don’t work as advertised.

The idea behind compression tights is that they greatly reduce muscle vibration, which in turn reduces muscle fatigue. But as a new study led by Ajit Chaudhari from Ohio State University’s Wexner Medical Center has shown, this claim is probably a stinky pile of horseshit.

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“When your muscle vibrates, it induces a contraction that uses energy, so the theory was that less muscle vibration would translate to less fatigue,” said Chaudhari in a statement. “However, the reduced vibration was not associated with any reduction in fatigue at all. In our study, runners performed the same with and without compression tights.”

For the study, the details of which were recently presented at the American College of Sports Medicine’s annual meeting, Chaudhari had 17 participants run on a treadmill for 30 minutes at 80 percent of their maximum capacity. This was done on two different days, once with the compression tights on and once without them. Motion capture technology was used to analyze each runner’s body position within a fraction of a millimeter. The researchers also measured the participants’ leg strength and jump height before and after each run.

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“Even though there was that reduction in vibration, that didn’t have any effect on their fatigue, their strength, [or] their jump height.” said Chaudhari. And as he told TIME, “We don’t see any evidence that they result in improvement in performance, so for someone who is wearing the tights specifically to try to improve performance, I’d say there isn’t any evidence that they are worth the time or money.”

Another supposed benefit of the compression tights is that, because they’re supposed to stave off fatigue, they prevent runners from adopting bad running form as they grow tired, which places more strain on their joints and contributes to injury. Further research conducted by Chaudhari’s team suggests this isn’t the case, and that experienced runners weren’t placing more strain on their joints at the end of a training run compared to the beginning.

Now, all this doesn’t mean compression tights don’t serve a purpose. Aside from making a fashion statement, they could provide a psychological boost for those who choose to wear them. Also, the runners were only tested for 30 minutes; it’s possible that the compression tights could confer benefits after longer distances, but that would have be demonstrated with controlled experiments.

“There is nothing in this study that shows it’s bad to wear compression tights,” he said. “Every little bit of perception counts when running long distances, so they may help runners in ways we aren’t able to measure.”

As noted, this study was made possible by a research grant from Nike. In a rather bland statement, the company said:

Our goal is to better understand all aspects of human performance. The effect of compression products on performance is one of many areas we study and an area that is often studied by other researchers. The Ohio State University study, which focused on 17 athletes for up to 30 minutes per athlete, produced an interesting data point that delivered an additional perspective on the study of compression tights. Our role is to take athlete feedback and data from studies like this to develop world-class products for athletes at every level.

“An interesting data point that delivered an additional perspective.” That’s a rather laughable way for Nike to admit their product doesn’t really work.