<s>[INST] Hello, I m a hiker and recently have been experiencing knee pain. No known injury. No swelling and I can do other exercise with no pain, such as arc trainer and treadmill. The pain happens when I m hiking. No swelling. Pain responds to ibuprofen. I m 54 years old. [/INST] Hi, as you mentioned your age and a brief history I suspect it to be a minimal muscle weakness of the knee. As we age the body becomes weak and degenerative changes keeps happening. You need to do some knee strengthening exercises like reverse walking and jogging which will avoid this end range pain and help the end of range of muscle torque. Avoid using treadmill for time being and focus on free exercises. With the grace of God I wish you a speedy recovery </s>