Differences in heart rate reserve during occupational and leisure time physical activity in Danish blue-collar workers

Aim: Physical activity (PA) is considered to be an important factor in the prevention of various cardiovascular diseases. However, recent studies suggest that while leisure time PA promotes cardiovascular health, occupational PA might impair cardiovascular health. An explanation for this PA health paradox may be a difference in the intensity and associated physical demands between occupational and leisure time PA. Occupational PA often consists of low-intensity, long-lasting physically demanding tasks, such as repetitive work and prolonged static working postures, which are presumed to cause sustained elevated heart rate that may stress the cardiovascular system. Despite this notion, the differences in physiological responses between occupational and leisure time PA are not well understood. Therefore, we aimed: (a) to study the difference in intensity of occupational and leisure time PA (expressed in percentage heart rate reserve; % HRR); and b) to assess whether this potential difference varies by gender and cardiorespiratory fitness level. Methods: We used data from the NOMAD study, in which Danish blue-collar workers from seven different workplaces took part in a four-day protocol of objective measurements of PA (using hip and thigh-worn accelerometers) and heart rate (using an ambulatory heart rate monitor). During occupational and leisure time, activities of sitting, standing, moving, walking and stair climbing were identified, and %HRR in each of these activities was determined. Differences in %HRR between occupational and leisure time PA were tested using generalised estimating equations (expressed in regression coefficient – beta with 95% confidence interval (CI)) adjusted for personal, health,work and lifestyle confounders. Result: In 124 workers with data on PA and heart rate, %HRR was higher for occupational PA compared to leisure time PA (beta1.9, 95% CI2.4,1.4,P<0.001). Differences in %HRR between occupational and leisure time PA were more pronounced
DOI: 10.1177/2047487317698870