Being a major sceptic of medical claims I decided to perform an A/B test on my knees. I live in a 3 story house and need to climb 2 flights of stairs continuously through the day, often with heavy loads. My 68 year old knees have been complaining with low level pain and stiffness. I have applied TENDLITE 3 times a day for 10 minutes (5 knee locations) to my right knee for the past week. Pain and stiffness has decreased in my right knee while my left, untreated knee, remains the same. The TENDLITE certainly seems to be have a beneficial effect. I will continue the test for another week, check the results, and start to work on my left knee if the test is successful.