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Heavy weight lifting is generally considered the immediate cause of herniation of the intervertebral discs. It has been surmise that pressure sensitive nerve endings may be located in these structures which may trigger the preventive pneumatic mechanism. A histological study (Kumar and Davis 1973) has failed to reveal any such nerve endings in the intervertebral discs. However, if compression of these structures is liable to evoke increases in hydrostatic and pneumatic pressure in the truncal cavitics (Bartelink 1957, Davis 1956, 1959) in defence of the intervertebral discs, such a pressure rise may also occur during axial loading. Thus human volunteers were loaded axially. They were asked to manoeuvre the weights above the shoulders with as little displacement as possible from the line of gravity of the body. The variations of the intra-abdominal pressure and electro-myographic activity of the crectores spinae and external oblique were studied. In addition to some observations on spinal motion during the manoeuvre, a check on heart rate was also kept.