The aim of the work is to establish guidelines for force applications by all normal female workers which can be used to assess the acceptability of existing working conditions, and to assist in the design of new working procedures. A significant relationship between lumbar stress and increase in intra-abdominal pressure has been established for females which is sufficiently sound for use when investigating load handling by women in industry. Female occupations with differing incidences of posterior trunk injuries have been identified and it has been shown that the lumbar stresses sustained by the high- and low-risk groups are different. This difference has been used to create a provisional level of lumbar stress for female which, if exceeded sufficiently often, might increase the risk of a back injury. Force limits for a fit young female population based on this provisional level are, on average, between 45 and 60% of the corresponding male limit values. It is hoped to confirm these findings in the near future.