question: Yes, I hope so. I stand on anti-fatigue mats at work. My knees stiffen within minutes after standing or walking on these anti-fatigue mats. 10 years ago, I stood on these mats and after a month, or sooner, I noticed my knees would stiffen quickly as soon as I stood on these anti-fatigue mats. At that time, the mats were called anti-static mats and were used to stop the transfer of static to the medical instruments used. I told a coworker about the problem. Instantly, my coworker called over her husband. He explained that he has the same problem and had knew surgery. When he came back from surgery and recovery time off, he stood on the mats and pain shot through his knee. Then, he realized that the mats are the problem. He told me about others in the lab who have had surgery on their knees due to the problems cause by these mats.