The main reasons for back pain after intercourse are the following: a. Back pain after intercourse may be caused by disease. If a man is suffering from prostatitis, it can also cause lumbago after intercourse and should be checked to confirm the diagnosis. The frequent intercourse can cause lumbago, mainly because the lumbar activity is too much, causing lumbar muscle strain, so that the lumbar muscles produce soreness. Third, interrupted intercourse can also lumbago. From the physiological point of view, interruption of conjugal life can make the entire reproductive system and pelvic congestion, can not quickly subside, the cerebral cortex and spinal cord for a long time in a state of tension can not be calm, the spermatic vesicles and other accessory organs are not emptied, while the brain is still in a state of excitement, can not get a good rest, in the long run can cause lumbago. Fourth, the failure to reach orgasm can also lead to lumbago. If the internal and external genital organs are stimulated by congestion, but not reached orgasm release, it may cause lumbago.