My son injured his lower back (may be the ejector spinae or psoas muscles) while stretching and late hitting an above the shoulder ball on the forehand. After a week of rest and rehab he regained full motion in all of his exercises and stretches without pain. The stretch that took the longest recovery time to do pain free was bending over and touch the ground with finger tips while standing straight up with no knees bend. Anyway, after two successful (pain free) practice (2hours each) sessions, he played a set against another kid and reinjured his lower back at the same spot. This time due to an outstretched two handed backhand hit. Did he return to competition too early? If yes, how does one knows when to return to competition after an injury especially when full motions are regained. A great many thanks!