Intra-abdominal pressure as a quantitative measure for spinal stresses

The purpose of this study was to measure the effects of lifting, placing, and removing different magnitudes of loads on the spinal stress. Eight male volunteers were measured for spinal stress utilizing intra-abdominal pressure (IAP). The loads used in the lifting tasks to different vertical and horizontal levels, varied from 5 kg up to 15 kg and were placed in a random order. The ANOVA analysis revealed significant individual variation (p < 0.001) both when placing and removing the loads. The effect of increase in load magnitude on the mean peak IAP values was highly significant (p < 0.001) when both placing and removing the loads. It is suggested that the area of activity falls within the limits of low truncal stress. The low truncal stress limits are large enough for most loading or unloading activities. Such requirements should also apply to physical therapists using passive movements and transfer activities allowing the therapist to carry out the required treatment or transfer within the safe limits of low truncal stress. J Orthop Sports Phys Ther 1987;9(2):70-76.