Musculoskeletal Model for Assessing Firefighters' Internal Forces and Occupational Musculoskeletal Disorders During Self-Contained Breathing Apparatus Carriage

Background: Firefighters are required to carry self-contained breathing apparatus (SCBA), which in-creases the risk of musculoskeletal disorders. This study assessed the newly recruited firefighters' in-ternal forces and potential musculoskeletal disorders when carrying SCBA. The effects of SCBA strap lengths were also evaluated.Methods: Kinematic parameters of twelve male subjects running in a control condition with no SCBA equipped and three varying-strapped SCBAs were measured using 3D inertial motion capture. Subse-quently, motion data and predicted ground reaction force were inputted for subject-specific musculo-skeletal modeling to estimate joint and muscle forces.Results: The knee was exposed to the highest internal force when carrying SCBA, followed by the rectus femoris and hip, while the shoulder had the lowest force compared to the no-SCBA condition. Our model also revealed that adjusting SCBA straps length was an efficient strategy to influence the force that occurred at the lumbar spine, hip, and knee regions. Grey relation analysis indicated that the deviation of the center of mass, step length, and knee flexion-extension angle could be used as the predictor of musculoskeletal disorders.Conclusion: The finding suggested that the training of the newly recruits focuses on the coordinated movement of muscle and joints in the lower limb. The strap lengths around 98-105 cm were also rec-ommended. The findings are expected to provide injury interventions to enhance the occupational health and safety of the newly recruited firefighters.(c) 2022 Occupational Safety and Health Research Institute, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).