A COMPARISON OF RISK ASSESSMENT OF SINGLE AND COMBINATION MANUAL HANDLING TASKS .3. BIOMECHANICAL MEASURES

Anecdotal evidence suggests organisations experience difficulty assess ing the risk in manual handling tasks. One reason for this difficulty may be that many common tasks are a combination of lift. lower. push, pull and carry tasks, No prior reports of attempts to assess the risk in combination tasks using biomechanical measures could be found. The aim of the study was to compare the risks assessed in single manual ha ndling tasks with those in combination tasks. Nine male and nine femal e students performed combination and single handling tasks. The force applied by subjects to a box was recorded and, together with kinematic data on subject posture collected via video, used in a two-dimensiona l dynamic model to estimate the lumbar compression force and lumbar sh ear force. The hand force, peak lumbar compression force and peak lumb ar shear force for each combination task were each compared with the s ame variable for the single tasks which comprised the combination, usi ng repeated measured analysis of variance with specific contrasts. In at least one of the twelve comparisons performed for each dependent va riable, the combination task value was significantly different to the single task value. It is concluded that the risk in combination manual handling tasks can not be accurately assessed by using estimates base d on biomechanical measures of single tasks.