Physical activity is typically measured in four domains: occupational, transportation, household, and leisure-time activities (1). In the domain of occupation, a traditional focus has been on physical demands FK(1 (e.g., repetitive motion, heavy lifting) in relation to musculoskeletal disorders refFK(2 ; however, on the rise of obesity rate in the United States, health impacts of sedantary work (i.e., physical inactivity) has attracted attention refFK(3 . Regardless of the domain, physical acitivity is considered to provide health benefits, but recent studies have suggested that high levels of occupational physical activity may be harmful to cardiovascular health, especially for people with low levels of leisure time physical activity (2-5). In contrast to leisure time physical activity, which is characterized by increasing whole-body metabolism and cardiac output with ability to rest at fatigue, occupational physical activity is a required rather than optional activity and requires high frequency and long duration(6). Previous studies indicate that occupational physical activity is generally negatively correlated with leisure time physical activity (7), and that the effects of occupational physical activity may depend on leisure time physical activity (8). Ignoring the potentially complex relationship between occupational and leisure time physical activity may obscure the true effects of occupational physical activity (8).
FK(1NIOSH reviewer was concerned with the lack of clear distinction between occupational physical demands and occupational physical activity. I hope this insertion will do.
FK(2da Costa, B. R., & Vieira, E. R. (2010). Risk factors for work?related musculoskeletal disorders: a systematic review of recent longitudinal studies. American journal of industrial medicine, 53(3), 285-323.
FK(3Choi, BongKyoo, Peter L. Schnall, Haiou Yang, Marnie Dobson, Paul Landsbergis, Leslie Israel, Robert Karasek, and Dean Baker. “Sedentary work, low physical job demand, and obesity in US workers.” American journal of industrial medicine 53, no. 11 (2010): 1088-1101.