Rheumatoid arthritis can slowly take away muscle mass. So, it’s important to work out your muscles to help them stay strong.
If you have swollen joints, you can do isometric exercises. They hold your muscles in one place. They also don’t make you move your joints.
If your joints aren’t swollen, isotonic exercises (movements that work against resistance, like weightlifting) are good for building up muscles.
Talk to your doctor before you start any kind of strength training.