I am a 36-years-old female and have arthritis. It affects my hips and knees the most. That said, I've continued to run the last several years just taking it easy when I needed to. However, a couple years ago I started having problems with my foot. I trained for and ran a full marathon without much trouble but it was my next half that gave me the problems. Afterwards, I had to back off the running for a while. Several weeks went by and I had to get back outside and run. The pain was immediately back. I had been looking online for something that I could do which would allow me to run without the impact. I hated treadmills, which left me more sore than ever, and the bicycle just didn't leave me feeling satisfied that I'd gotten a good workout. I found the information about the Zero Runner and I kept reading it over and over. I located the nearest dealer and went to their store so that I could see it in person and try it out. First off, the owner, Mike, was awesome. He answered every single question my husband and I had and he showed me absolutely everything there was to see on the machine. The cost was a little bit concerning as I've never spent that much on a machine before. I took the info and went home. Two days later, I called Mike up and made my purchase. Now, almost three months later, I can say this was hands down the best purchase I have ever made. When I was trying to only run outside through the foot pain, I was lucky if I was getting 5-8 miles in through the whole week. Now, I'm running over 30 again. No pain anywhere. Not in my feet, my hips, my knees, not anywhere. I knew that when I was first starting, I worried about whether I could transition easily from running on the Zero Runner to running outside. I'm not a fast runner at all. Never have been. The first couple months on the ZR7, I was consistently doing between an 11 and 12 minute mile. Just two months after working out on the machine, I did a 5K. I ran a PR of 28 minutes and was not struggling at all. That to me was when I knew that the transitioning was not going to be a problem at all. This machine has been nothing short of a miracle for me. Now on the days I run outside, I don't have the pain either. I would highly recommend it for anyone who is injury prone or just wants a way to add in more miles without the pounding. Thank you, Octane Fitness, for creating this amazing piece of fitness equipment.