No abstract

No abstract

Based on the scientific evidence in published literature about precipitation of musculoskeletal injuries in the workplace, four theories have been proposed to explain these afflictions. Central to all theories is the presupposition that all occupational musculoskeletal injuries are biomechanical in nature. Disruption of mechanical order of a biological system is dependent on the individual components and their mechanical properties. These common denominators will be causally affected by the individual's genetic endowment, morphological characteristics and psychosocial makeup, and by the occupational biomechanical hazards. This phenomenon is explained by the Multivariate Interaction Theory. Differential Fatigue Theory accounts for unbalanced and asymmetric occupational activities creating differential fatigue and thereby a kinetic and kinematic imbalance resulting in injury precipitation. Cumulative Load Theory suggests a threshold range of load and repetition product beyond which injury precipitates, as all material substances have a finite life. Finally, Overexertion Theory claims that exertion exceeding the tolerance limit precipitates occupational musculoskeletal injury. It is also suggested that while these theories may explain the immediate mechanism of precipitation of injuries, they all operate simultaneously and interact to modulate injuries to varying degrees in different cases.

Working postures are addressed in many papers in the ergonomics field but, surprisingly, scientific literature dealing with working posture itself is not common; knowledge has been elusive. This article reviews the working postures literature. Selected papers published in the English language before March 2003 including the phrase "working postures" in the title, abstract, or keywords were searched in the PubMed, Scirus, and Science Direct databases and reviewed. The literature provides evidence that working postures and musculoskeletal health are related. This relationship is supported by the overexertion, differential fatigue, and cumulative load theories of musculoskeletal injuries' precipitation. Goniometers, inclinometers, photographic techniques, electrogoniometers, and video recording systems are the means that are most often used to measure working postures. Information about working postures need to be collected and analyzed in a more systematic way in order to contribute for a deeper understanding of the relationship between working postures and work-related musculoskeletal disorders. This information will help to improve the control and rehabilitation of these highly prevalent disorders.

No abstract