Training exercises are what athletes do. They raise the heart rate, cause one to breathe heavily, and are often painful. Heart rate, breathing, and pain can reach extreme levels. Healing exercises should be done by anyone in recovery from surgery. The barely raise the heart rate or breathing levels and most importantly do not cause pain beyond a mild discomfort.
Following joint surgery, healing exercises such as stretching should be an integral part of recovery from Day 1, but it’s important not to undertake training exercises until healing is well underway or complete. Training exercises work by causing minor damage to muscle tissue (hence the pain), which heal back stronger. It doesn’t work that way with ligaments and tendons. Pain is indeed an indication of damage which usually will set back your healing process.