I normal train in DS trainers and was looking to try a neutral lightweight trainer to replace them. I also have a 10 mile race in a couple weeks and was looking for a shoe for that. I got a really good deal on the tarthers so I thought I would give them a try. I took them out on a brisk 12 mile run today on concrete/asphalt to see how they might feel for a 10 miler. First 8 miles I had no problems but then after that my knees were screaming. I don't know if it had to do with the lack of a support or less cushion or if it is to much of a change from a DS Trainer type shoe. I thought they might be similar to the DS Racers which I've used in the past for marathons. Is the transition from support shoes like the DS Trainers/Racers to neutral shoes like the Tarther that big of a difference?