Workplace risk factors and occupational musculoskeletal disorders, part 2:A review of biomechanical and psychophysical research on risk factors associated with upper extremity disorders

Injuries and disorders caused by overexertion and repetitive motion are the leading causes of compensable lost-time cases in the United States. Epidem iological and laboratory-based research methods have been used to evaluate the significance of various risk factors associated with overuse injuries a nd disorders. The National Institute for Occupational Safety and Health per formed a comprehensive review of over 600 epidemiological studies in 1997 a nd concluded that there was evidence of a causal relationship between workp lace exposures to forceful exertions, repetition, awkward posture, and vibr ation and disorders of the neck, shoulder, and upper extremities. Although epidemiological studies provide important insights to understanding the cau ses of work-related overuse disorders, they are sometimes criticized for th eir inability to measure precisely how people respond to specific risk fact ors found in the workplace. This article presents a review of recent labora tory studies and biomechanical models of work factors believed to be associ ated with increased risk of upper extremity injuries and disorders. Biomech anical models and laboratory studies do not replace epidemiological studies . However, these approaches provide important complementary information tha t is needed to understand the complex process of how exposures to physical risk factors result in strain that may ultimately lead to injury or disease . These studies also provide important insights as to how people react and respond to specific physical risk factors found in the workplace, Combined with epidemiological research, laboratory studies are an essential element in understanding the causes and prevention of work-related overexertion inj uries.