When someone advises you to lift with the knees and not the back, it really is advice you should be heeding according to many doctors.  The results of forcing your body the wrong way could result in a painful hernia.  You likely heard about hernias but don’t know what they are.  Hernias are the result of tissues or organs forcing their way through muscle walls or ligaments due to excessive pressure.  In some cases, hernias can even be detected in advance and you can request a check-up from your doctor.  Heavy lifting in the wrong way can cause a hernia because of all the pressure it exerts.