Impact of Self-Contained Breathing Apparatus (SCBA) Weights on Firefighter’s Kinematics During Simulated Firefighter Tasks
Authors: Xu Susan , F Jones Rachel , Ratnakumar Neethan , Akbaş Kübra , Powell Jeffrey , Zhuang Ziqing , Zhou Alex 
Published: June 2024

Firefighters face a multitude of hazards in their line of duty, with overexertion being the foremost cause of injuries or fatalities, as referenced in studies [1, 2]. This high risk is often amplified by the physical demands of their role, further exacerbated by the burden of carrying heavy SCBA. The objective of this research is to examine how the weight of SCBA affects the musculoskeletal joint movements of firefighters. There is an urgent requirement for precise measurement and analysis of firefighters' movements to understand the impact of SCBA weight on both performance and injury risk. Traditional motion capture techniques, which are primarily optical-based or inertia-based, have their limitations, such as marker obstructions due to clothing or lower accuracy and drift issues. To overcome these obstacles, this study introduces a groundbreaking hybrid motion capture technique, combining the advantages of both existing methods. This new method is expected to offer a detailed and accurate evaluation of how SCBA weight influences the kinematics of firefighters.MethodsIn this study, six professional firefighters (average age: 34.2±5.2 years) were involved in performing four simulated tasks: stair climbing, searching, hose advance, and overhaul, under three different SCBA weight scenarios: only gear, gear with a standard 45-minute SCBA, and gear with an SCBA plus an additional 10 lbs (SCBA-10). Data collection included optical markers on key equipment like helmets, boots, and gloves, 17 IMUs, EMG, pressure insoles, and a metabolic mask. A novel hybrid inverse kinematics method, blending IMU data with optical markers, was utilized to minimize drift errors and precisely reconstruct joint movements. Joint angle data, particularly for hose advance and overhaul, were segmented and normalized for comprehensive statistical analysis. Preliminary Results and DiscussionInitial analysis of data from two human subjects showed that heavier SCBA weights led to increased hip joint movement during stair climbing, with a noticeable 10% increase in hip angle range under the heaviest SCBA condition (SCBA-10). In hose advance tasks, firefighters showed less lumbar extension with SCBA, indicating a preference for using arm movements over the back and torso to maneuver the hose. Traditional inverse kinematics with only markers showed significant errors in joint angles, especially in pelvic tilt and hip flexion, which were effectively corrected with the new hybrid method. This innovative approach allows for a more precise evaluation of the effects of SCBA weight on firefighter kinematics and musculoskeletal load. Additional data is expected soon, which will provide a greater understanding of the effects of SCBA. While our current analysis is based on a small sample, we expect that expanding the study to more participants will reveal further kinematic changes due to loading.Preliminary Conclusions To the best of our knowledge, this research represents the first endeavor to precisely record the movement of firefighters engaged in activities while fully equipped with gear and SCBA using both inertia and optical motion capture systems. Our initial findings validate this method and suggest its potential to refine SCBA weight standards based on scientific evidence. We noted that SCBA's weight substantially modifies the movement patterns of firefighters, possibly increasing musculoskeletal strain. This research paves the way for future dynamic analyses and contributes significantly to understanding how SCBA weight impacts musculoskeletal health, ultimately provide the possibility of recommending SCBA weight limits for injury prevention.DisclaimerThe findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC).References[1]M. M. Alemi, J. Geissinger, A. A. Simon, S. E. Chang, and A. T. Asbeck, "A passive exoskeleton reduces peak and mean EMG during symmetric and asymmetric lifting," Journal of Electromyography and Kinesiology, vol. 47, pp. 25-34, 2019.[2]M. J. Karter, "Patterns of firefighter fireground injuries," National Fire Protection Association, 2014.[3]S. Wang, C. Feng, X. Chen, M. Shan, and W. Niu, "A biomechanical evaluation of firefighters’ musculoskeletal loads when carrying self-contained breathing apparatus in walking and running," Journal of Safety Research, 2023.