Reducing the biomechanical stress of lifting by training

The effectiveness of two methods of training in reducing biomechanical stress during lifting was examined in a sample of 12 men aged 18-40 years. Subjects carried out three 40 min sessions, one session per day, of a simple symmetrical lifting task. No training was given before the first session, which acted as the control condition. before each of the next two sessions training was given in the form of either written guidelines or interactive personal tuition in a crossover design. Interaction of order with method was expected and was of interest. The effectiveness of each training method in relieving the stress of lifting was measured in four ways: by ratings of perceived exertion on the Borg scale; by video analysis of adherence to guideline kinematics; by chronic spinal compression measured by precision stadiometry; and by the relative compression force at L5/S1 calculated using Chaffin's model. Although the differences in the results of the four assessment methods make reservations necessary it is suggested that while brief personal tuition may demonstrably reduce lifting stress even in a simple lifting task, written guidelines for the untrained may be counterproductive and may interfere with habitual skills. It is recommended that the efficiency of lifting training methods be estimated objectively, such as by the methods employed here, before being adopted.