For a chronic pain condition, such as osteoarthritis, heat seems to work best. However, some people find that cold also helps to dull the pain. So the answer is, try them both and use whichever works best for you. Exercise is an important part of treatment for osteoarthritis. Heat and cold can also be used to make exercising a little easier. Try using heat before exercise to loosen up muscles and cold afterwards to minimize any achiness.