Spine loading during laboratory-simulated fireground operations - inter-individual variation and method of load quantification

Spine loading data are needed to design low-back health-preserving ergonomic interventions for firefighters. Study objectives were to quantify spine loads during simulated fireground operations using simple (polynomial) and advanced (EMG-assisted musculoskeletal model) methods and to describe the variation in spine loads between performers (N = 20). Spine compression forces differed by as much as 5.5 times bodyweight between individuals performing identical tasks. Anteroposterior and mediolateral shear forces varied by as much 3.2 and 2.1 times bodyweight between individuals performing the same tasks, respectively. Large variations in spine load magnitudes were documented regardless of whether simple or advanced quantification methods were used. Results suggest that low-back loading demands on the fireground would vary widely depending on the physical characteristics of individual firefighters, movement strategies employed, and tasks performed. Thus, personalised ergonomic interventions are warranted to regulate spine loading and load tolerance in firefighters. Practitioner summary: Even when performing the same work, the associated spine loading demands will vary widely across people due to differences in their body sizes, shapes, and movement strategies. Therefore, personalised interventions are needed to regulate spine loading and load tolerance in workers (e.g. obesity prevention, physical capacity-building exercise, and movement [re]training).