On the bending moment capability of the pressurized abdominal cavity during human lifting activity

Abstract

A theory has been developed for calculating the maximum bending moment which can be carried by the abdominal cavity pressurized by the intra-abdominal pressure. It is predicted that this bending moment is independent of the thickness of the abdominal wall and varies as pA ^3/2, where p is the intra-abdominal pressure and A is the cross-sectional area of the abdominal cavity. An example has illustrated that the bending moment is capable of reducing the compressive load on the lumbar spine and the tensile load in the lower back muscles by about 20% during heavy lifting activity. Based on the theory an hypothesis is advanced to explain why certain types of lower back injury may occur during physical activity.

Keywords:

• Intra-abdominal pressure
• Lumbo-sacral
• Region
• Lifting