Hey CT you have said in the past that you had a 57 yr old middleweight bodybuilder who only did prowler work twice a weak and it cleared up his knee pain. Do you know how this is possible that his pain went away?
Not CT, but i used sled work in my appraoch to clear up a vastus medialis strain that I had in the belly of the muscle. The knee however is not a muscle and it is stablized by several ligaments. As a Physical Therapy student in college and from currently working in a Physical Therapy clinic all through college the Physical Therapists only use eccentrics by doing bodyweight exercises or use of Theraband (which has minimal eccentric) in some of thier Therapy protocols. We also have a sled like device that we use in rehab under specific regimens for patients.
As for me I was able to do sled work for lower body stimulation for one week until I recovered from my strain. i used ice as well after every eccentric-less session to help with the recovery process. The actual Physical Therapists told me to lay off the Front Squats (that is the lift in which i strained my quad). So to make the best of it i didnt want to just stop doing lower body pressing all together, i did the next best thing and hit the sled. After I week I went back to lower body pressing and not only was the pain gone, but my work capacity did not suffer as well.
I have no knowledge of the 57-year client CT worked with, but as noted by CT eccentric's for the lower body can cause great CNS damage when not monitored. In my experience in Physical Therapy eccentric's can cause great damage to the joints and joint stabilizers as well. He may have recieved Physical Therapy as well as doing sled work to increase his recovery for his injury.