The principal objective of the proposed research is "to evaluate whether the knowledge of an individual's physiological endurance and strength can predict the risk of later injury and illness when the individual is placed on jobs requiring high frequency lifting tasks". A lifting stress index (LSI) based on both endurance and strength will be developed to meet this objective. The LSI is defined in this study as the ratio of lifting task demands (LID) and worker lifting ability (WLA). WLA will be determined through a set of predictive models that will be developed in the principal investigator's laboratory, at the University of Miami, using a large sample of male industrial workers. LTD, which will be collected in a field study conducted by Western Michigan University from companies, will be described in terms of task variables, worker characteristics, and injury statistics. A knowledge-based system will be developed using the information collected from the laboratory study and participating companies. This system can be used by companies in the design or redesign of continuous high frequency lifting tasks.