I have arthritis in both knees which hampers boxing training sometimes. After I took a slip on the ice one December and sprained my right knee, I had X-rays done. "No wonder my knees have been hurting for years," I commented when the doctor told me what he found.
The condition is a breaking down of one or more joints. It causes pain, swelling, stiffness, and can make it very hard to use the joints to move. I have pain in my knees every day, and it's a challenge to move around in the ring during boxing training. The cartilage, which projects the joints and allows for smooth movement in both knees is wearing away. The condition is often a result of autoimmune disease, or broken bones, or infections caused by bacteria and viruses. I suspect mine is from plain old general wear and tear done over the years.
Aging is often cited as another factor, but this condition can affect anyone at any age. In order to make sure another muscleskeletor problem is not the cause of joint pain, it's best to get tested by a doctor. The doctor will try to find what's causing it and map out a plan of action. However, even the the doctor may pinpoint the cause, it may not mean there will be a means to make it go away permanently. Some forms of it are chronic.
Prescription drugs may help others, and taking aspirin to alleve discomfort once in awhile may help others. In my opinion, exercise is best in order to keep the joints lubricated and flexible. Strength training exercises as well as exercises for flexiblity are useful. But people have to be careful. If the joints are already compromised, injuring them further is not going to help.
Various gels and heat pads can help with joint pain while working out. Wrapping the joints -- after putting on the gels or creams -- is another suggestion.