Exercise is crucial if you have arthritis. But knowing how much activity do when you’re hurting it can be difficult. Although mild muscle soreness after a workout is normal, severe pain during or immediately after the signal can injury.

We speak with Richard Kassler physical therapist, supervisor of Orthopedics and Sports Therapy Center of New York University Hospital for Joint Diseases in New York and rheumatologist James O’Dell, MD, president of the American College of Rheumatology Research and Education Foundation in Atlanta, to obtain the guidelines for when it is okay for people with arthritis to work with pain in the exercise – and when it is not:

If you have moderate to severe pain in a specific joint area before working out:
Focusing on a different area for a day or two – if your knees hurt, do not use the lower body strength training routine, and work your upper body instead. “To continue to put pressure on a joint when pain is especially could contribute to joint damage, so it is best to ease for a while,” says Kassler.

If you have moderate to severe pain in the joints during exercise:
Cease immediately. “Most people with arthritis can work through a mild pain safely. But if you are experiencing great pain while exercising, even if you’re not doing a particular training set of taxes can be a sign you have inflammation in the joint, or joint damage that requires treatment, “says Kassler.

If you have had joint pain (not muscle pain) after exercise:
Changing to a workout that puts less stress on your joints. “If you need an elaborate brace or constantly pop ibuprofen is a good indicator that your activity is hard on your joints,” says Dr. O’Dell. Swimming, water aerobics and bicycling are a good option for people with joint pain.

If you sometimes have moderate to severe pain in the joints of the day after exercise:
Reduce the intensity of your workout. “If you’re really sore the next day, you probably exercised too much or too long,” says Dr. O’Dell. We suggest taking a day off, and then make a short, less intense workout. If your pain still does not let up, switch to a less intense form of exercise (such as trade in its elliptical training for water aerobics).