https://goturethane.com/polyurethane-in-the-fitness-industry/

Modern fitness equipment such as treadmills and motion specific fitness machines are full of polyurethane. Precision roller assemblies are used in strength training equipment to provide smooth and consistent motion for the user. Whether they are used in weight based machines, or resistance based machines such as rowers or rope-pull machines, polyurethane provides an unmatched workout experience.