Arthritis is a group of conditions that cause joint problems, and they becomes increasingly common in the later stages of life. In the most common type of arthritis, osteoarthritis, the joint cartilage gradually wears away, allowing the bones to grind against each other. The causes aren’t clear, but heredity, excessive weight, old age, lack of physical exercise, and injury all seem to play a part. If you have joint pain or stiffness that lasts for more than two weeks, it’s best to check it out with your doctor.
Although doctors can’t cure osteoarthritis, you may be able to avoid it—or at least delay its onset. The best advice is to adopt a regular routine of strength exercises. You should also avoid straining your joints with repetitive motions or dramatic changes in the way you use them. (For example, don’t expect your body to make the jump from weekday office worker to long-weekend football superhero.)
Source of Information : Oreilly - Your Body Missing Manual