ORIGINAL ARTICLE Association of Shift Work With Physical Activity Among Police Officers The Buffalo Cardio-Metabolic Occupational Police Stress Study Claudia C. Ma, MS, MPH, Cecil M. Burchfiel, PhD, MPH, Desta Fekedulegn, PhD, Michael E. Andrew, PhD, Luenda E. Charles, PhD, MPH, Ja K. Gu, MSPH, Anna Mnatsakanova, MS, and John M. Violanti, PhD Objective: To examine relations of shift work with occupational, sports, and household physical activity (PA) among police officers. Methods: Self- reported PA was assessed among 350 male and female officers (aged 27 to 66). Day, afternoon, or midnight shift was identified from daily payroll records. Results: Shift work was associated with prevalence of hard-intensity (occupational and sport) PA among men, and very hard-intensity sport PA among women, with afternoon workers reporting the highest prevalence. Shift work was independently associated with total hours of hard-intensity PA among men and very hard-intensity PA among women, with afternoon workers reporting the most hours. Conclusion: Results indicated that hard and very hard-intensity PA varied significantly across shifts with afternoon workers being the most active. S hift work is relatively common in the workforce. The Bureau of Labor Statistics showed that about 2% to 10% of employ- ees in almost any occupation worked in evening, night, or rotating shifts. 1 The Office of Technology Assessment of the US Congress documented the consequences of nonstandard schedules, including circadian rhythm disruption, sleep disruption and fatigue, and social and domestic disturbances, as well as a variety of health problems caused by the combination of these factors. 2 Epidemiological studies reported that shift work was associated with decreased sleep quantity and quality, 3 the metabolic syndrome, 4,5 metabolic risk factors for cardiovascular disease, 6 and prostate cancer. 7 A consensus has been established that physical activity (PA) is an effective method to improve health and prevent disease fol- lowing the publication of the 1996 US Surgeon General’s Report on Physical Activity and Health. At least moderate-intensity activity of 30 minutes on most days of a week is necessary for maintenance of general health and improvement of health-related quality of life by enhancing psychological well-being. 8 Longitudinal studies re- ported that moderate and high levels of occupational PA decreased cardiovascular disease (CVD) and all-cause mortality by 21% to 27% in both sexes, 9 and were associated with lower breast cancer risk compared with those who worked in sedentary jobs. 10 Regular leisure-time fitness training could improve the level of CVD risk From the Biostatistics and Epidemiology Branch, Health Effects Laboratory Di- vision, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, West Virginia (Ms Ma, Mr Gu, and Ms Mnatsakanova and Drs Burchfiel, Fekedulegn, Andrew, and Charles); and Department of Social and Preventive Medicine, School of Public Health and Health Professions, State University of New York at Buffalo, Buffalo (Dr Violanti). None of the authors have any conflicts of interest. The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Address correspondence to: Claudia C. Ma, MS, MPH, National Institute for Occupational Safety and Health, HELD/BEB, MS L-4050,1095 Willowdale Rd, Morgantown, WV 26505 (iia4@cdc.gov). Copyright C  2011 by American College of Occupational and Environmental Medicine DOI: 10.1097/JOM.0b013e31822589f9 factors, 11–13 decrease the risk of colon cancer, 14 and lower the risk of non–insulin-dependent diabetes. 15 Recently, moderate-to-hard- intensity household PA was reported to protect against all-cause and CVD mortality. 16,17 Physical activity level was also found to be inversely associated with mortality because of CVD. 18 A recent study has suggested that overweight and obesity were more prevalent among law enforcement retirees than the gen- eral population, 19 and lack of regular physical exercise is one of the occupational risk factors contributing to the higher prevalence of elevated blood pressure, metabolic syndrome, and CVD among emergency responders such as police officers. 20 Nevertheless, few studies have focused on associations of shift work with PA including occupational, sports, and household PA. To help police officers re- main or improve their health status, it is essential to understand how much PA the police officers have engaged in during work and leisure time. The present study examined the associations of shift work with prevalence and duration of PA from occupational, sport, and household domains among Buffalo male and female police officers. METHODS Study Population The initial examinations for the Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) study took place during the period of June 4, 2004 to October 2, 2009. The study design was cross-sectional and the overall goal was to examine associations be- tween physiological biomarkers of stress, subclinical metabolic and vascular disease markers, life style, and psychosocial factors among police officers. A total of 810 police officers in the Buffalo Police De- partment were invited to participate in examinations. One hundred officers were on long-term sick leave and were not able to partici- pate. Of the remaining officers, 466 chose to participate. Exclusions included two pregnant officers, yielding a cohort of 464 participants who completed examinations for the BCOPS study. This study was approved by the internal review board of the State University of New York at Buffalo, and the human subjects review board of the National Institute for Occupational Safety and Health. Shift Work and Physical Activity Assessment In 1994, a rotating shift schedule was changed to a fixed sched- ule that included day, afternoon, and night shift. The categorizations of the three shifts have been previously described. 3,5 Briefly, work schedules that started from 4 AM to 11:59 AM were classified as day shift, from 12 PM to 7:59 PM as afternoon shift, and from 8 PM to 3:59 AM as night shift. The majority of officers started the day, af- ternoon, or night shift at 8 AM,4 PM, and 12 AM, respectively. Shift for each officer was retrieved from daily payroll records for the 2- week period prior to date of examination. On the basis of the payroll records, the total hours worked on each shift were calculated for each participant, and were standardized to weekly basis. Day, afternoon, or midnight shift was identified for each officer on the basis of the Copyright © 2011 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. 1030 JOEM  Volume 53, Number 9, September 2011