THE SIGNIFICANCE OF THE ACTIVITY OF THE ABDOMINAL MUSCLES IN WEIGHT LIFTING

Abstract

An attempt has been made to calculate the magnitude of the upward thrust of the raised intra-abdominal pressure which occurs during weight lifting in the semiflexed posture, and also the length of the liver arm at which it acts. During this rise in intra-abdominal pressure the activity of the erectores spinae was studied, and an increase in activity was found. It is concluded that the tension developed in the anterior abdominal wall, although contributing to the upward thrust through the diaphragm, tends to flex the vertebral column, and that the associated increase in activity of the erectores spinae is a synergic response to neutralize this effect. It is suggested that the rise in intra-abdominal pressure associated with weight lifting serves to neutralize the compression effect of the latissimus dorsi on the chest wall.