¹Université Laval, Québec, Canada
²Centre interdisciplinaire de recherche en réadaptation et intégration sociale (CIRRIS), Québec, Canada
³Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST), Montréal, Canada
⁴University of Québec in Montréal, Montréal, Canada
⁵ELOY ERGO Consultants, Granby, Canada

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Introduction: The risk of musculoskeletal disorders (MSDs) associated to manual materials handling (MMH) is still very high today. The tangible effects of MMH training in preventing MSDs have not been clearly demonstrated. Inadequate training duration and an approach that does not consider different handling contexts and techniques of moving loads may explain this lack of effectiveness. Strategies to improve MMH skills should be based on the acquisition of motor skills adapted to the specific work context. The aim of this study is to evaluate the effectiveness of a new training approach that emphasizes structured practice and personalized feedback with novice handlers in reducing lower back loading profiles.

Methods: Twenty-nine novice MMH workers were recruited from local companies. Thirteen of them were assigned to a control group (who had received training from their employer) and sixteen participants were assigned to the training group (who had received the new 12.5-hour training course). In total, the new training program consists of 71 exercises with 562 objects handled. A cumulative mass of approximately 5.6 tons has been moved during the training sessions. Laboratory measurements taken before the training (T0), a few days after the training (training group only; T1), and 6-8 weeks after the training (T2) represent the Test independent variable. The laboratory task consisted in moving 4 consecutive 15 kg boxes from a conveyor to a hand truck dolly back and forth for a total of 32 box transfers. Kinematics and kinetics were measured to estimate external loads at the L5/S1 joint. Dependent variables were submitted to a mixed ANOVA (alpha < 0.05).

Results: A significant Group x Test interaction (p<0.01) was observed for the cumulative resultant moment at L5/S1, indicating a decrease in loading at T1 and T2 for the trained group, while the control group showed no improvement. There was no significant interaction between Group and Test factors or main effect for sagittal and asymmetric peak moments (p>0.05).

Discussion: Novice handlers who received the training were able to reduce the cumulative load on the structures of the lower back without increasing the peak activity at the same joint. Analysis of the operating techniques will highlight the different movement strategies used to achieve this.

Conclusion: It is expected that this project will pave the way for improved training to achieve the desired impact on MSD prevention for novice handlers.