I am a regular hiker (my favorite form of exercise) but unfortunately, I have been told I have arthritis on my knee. Based on a recommendation of a friend, I tried this MSM. I was really surprised by how soon I experienced relief. I was also surprised that it helped aching in the my fingers and knuckles that I didn't even think of until I had relief. The only reason I gave it 4 instead of 5 stars was that the taste is a little bitter (I take mine with a small glass of water). Very happy with this product for my joint aching!