The efficacy of training for three manual handling strategies based on the observation of expert and novice workers

Objectives. To evaluate the efficacy of training for three manual handling strategies, i.e. load tilting/hands positioning, shoulders positioning and feet orientation based on the observation of the contrasted strategies of expert and novice workers and free practice using a search approach. Design. Ten novice male workers were tested at pre-training (one trial) and post-training with homogeneous boxes (three trials) and heterogeneous boxes (two trials) sampled from two sessions. Training took place with homogeneous boxes whereas heterogeneous boxes were new situations. Background. The effectiveness of training programs in safe handling and the repetition of specified techniques are contested; they should rather be based on expert workers' strategies. Methods. Pre-training and post-training trials were analyzed with five video cameras and a large force plate. The biomechanical variables included three safety criteria: net 3D resulting moments at L5/S1, asymmetry of posture/efforts at L5/S1 and mechanical work on load; kinematics and ergonomic variables were used as explicative variables. Results. Training produced safer strategies by reducing mechanical work and back extensor moments; this occurred in both load conditions, an indication of the transfer of knowledge. These strategies consisted of changes in load maneuvers (tilting/hand positioning) and feet orientation. Conclusions. Training programs should be based on observations of workers.