Hyundai España’s YouTube page has posted a commercial (spotted by Motor1) showing Olympic swimmer and brand ambassador Mireia Belmonte running on a treadmill inside a sealed bubble. The video clearly shows that a Nexo’s exhaust is connected to the structure. While Hyundai stressed that its vehicle only emits water and 99.9 percent filtered oxygen, it still worked with the Spanish National Centre on Hydrogen and a sports medical center to make sure the whole process was safe.

As Autoblog noted, the video works in tandem with the Hyundai Eco Road Show that’s now touring Spain to demo the automaker’s eco-friendly vehicles. You can check out the whole video below, though needless to be said, don’t try this at home.