The Bottom Line: Fatigue Failure and Cumulative Tissue Damage
Posted on July 12, 2022 | in Ergonomics
The fatigue failure process is defined as the tendency of a structure (or tissue) to become damaged under cumulative stress or force. In this month’s edition, Research Director Blake McGowan, CPE, explains how musculoskeletal disorders (MSDs) may be the result of this process.
References: Gallagher S, & Schall MC Jr. (2017). Musculoskeletal disorders as a fatigue failure process: evidence, implications and research needs. Ergonomics. 2017 Feb;60(2):255-269; Gallagher S, Sesek RF, Schall MC Jr, & Huangfu R. (2017). Development and validation of an easy-to-use risk assessment tool for cumulative low back loading: The Lifting Fatigue Failure Tool (LiFFT). Appl Ergon. 2017 Sep;63:142-150.; Gallagher S, Schall MC Jr, Sesek RF, & Huangfu R. (2018). An Upper Extremity Risk Assessment Tool Based on Material Fatigue Failure Theory: The Distal Upper Extremity Tool (DUET). Hum Factors. 2018 Dec;60(8):1146-1162.
Hi, my name is Blake McGowan, and I’m a certified professional ergonomist with Humantech (now VelocityEHS Ergonomics). One of the questions I get asked a lot by safety professionals is, what is the cause or mechanism of musculoskeletal disorders, or MSDs, in the workplace? We all understand the physical risk factors associated with MSDs, exposure to forceful exertions, awkward postures, long durations, and high frequencies. But what’s the physiological mechanism that causes MSDs?
Well, there’s mounting evidence based on research from Sean Gallagher and colleagues from Auburn University that the fatigue failure process is the mechanism for MSDs in the workplace. So, what is the fatigue failure process? It is defined as the tendency of a structure to become damaged under cumulative stress and force, and it’s based on evidence from cadaver tissue studies, in vivo animal model studies, as well as tissue pathology studies. Simply put, it states that the highest magnitude forceful exertion or awkward posture that the worker is exposed to causes the most daily cumulative tissue damage. This relationship is so strong that it expresses a dose-response relationship.
So, what does this mean? What’s the bottom line? The bottom line is that evidence shows that the fatigue failure process is the physiological mechanism that causes MSDs in the workplace.