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Introduction: Manual handling (MH) continues to be a leading cause of work-related ill-health, carrying substantial personal and financial costs. It is estimated that sprains or strains cost the New Zealand’s Accident Compensation Corporation (ACC) $529.6M in 2019 (ACC, 2020). MH training remains a primary preventative strategy, despite the lack of evidence to support its benefits. The aim of this study was to determine whether recommended technique-based manual handling training influences the physiological demands and musculoskeletal loading during repetitive lifting.

Methods: 14 adult males (mean age 30.1 yrs) with no history of musculoskeletal, cardiovascular or respiratory disorders and with a normal Body Mass Index (BMI) participated in the study. Participants attended three sessions on separate days: session1 - cardiopulmonary exercise test (CPET) to ascertain physiological capacity; and session 2 and 3 involved a repetitively lifting and lowering task (box weight 13 kg) at a frequency of 10 lifts/min for up to 20 minutes. Session 2 and 3 differed in the instructions given to participants: no instruction versus training in ‘safe lifting’. Oxygen consumption (VO2), and heart rate (HR)) were recording throughout using a gas analyser (MetaLyzer 3B; Cortex Biophysik, Germany) and polar HR monitor (Polar Electro Oy, Finland). A paired T-tests was used to compare sessions, with significance set at p<0.05.

Results: Maximum HR (HRmax), % of peak HR attained during CPET, average VO2 (L/min), % of peak VO2 (VO2peak) compared to the CPET, and energy expenditure (kcal) were all higher and significantly different for the training session when compared to no instruction (p ranged between 0.015 and <0.001). HRmax reached a mean across participants of 136 beats/min for the training session compared to 127 beats/min for the no instruction session (p=0.007). When compared to no instruction, MH training increased %VO2peak from 43% to 49% (p<0.001) and energy expenditure increased from 132 kcal to 152 kcal (p=0.005).

Discussion: The higher physiological costs of a prescribed lifting technique could be a detrimental factor discouraging its use. Training should take into consideration the individual and the context of the work if the high incidence of musculoskeletal injuries arising from MH in the workplace is to be addressed.

Conclusion: The content and delivery of training should be based on a sound pedagogical rationale, which considers physiological demands.