Job strain and leisure-time physical activity on risk of hypertension: the population-based Midlife in the United States cohort study

Abstract

OBJECTIVES: Job strain is positively associated with incident hypertension, while increasing leisure-time physical activity (LTPA) can reduce incident hypertension. However, the joint associations of job strain and LTPA with incident hypertension among US workers have yet to be investigated. The objective of this study was to examine the independent and joint associations of job strain and LTPA with incident hypertension. METHODS: The prospective cohort (N = 1,160) utilized data from the population-based Midlife in the United States (MIDUS) study. The associations of job strain and LTPA at baseline with incident hypertension during follow-up were examined using Cox proportional hazards models. High job strain was derived from a combination of high job demands and low job control, and high LTPA was defined as engagement in moderate or vigorous LTPA at least once per week. RESULTS: During the 9,218 person-years of follow-up, the hypertension incidence rate was 30.6 (95% confidence interval: 27.3, 34.3) per 1,000 person-years. High job strain was associated with an increased risk for hypertension compared to low job strain (adjusted hazard ratio: 1.29 [1.004, 1.67]). High LTPA was associated with reduced hypertension risk compared to low LTPA (0.77 [0.60, 0.98]). Hypertension risk was higher among workers with high job strain and low LTPA than those with low job strain and high LTPA (1.70 [1.18, 2.43]). CONCLUSIONS: Job strain was positively but LTPA was inversely associated with incident hypertension. The combination of high job strain and low LTPA was associated with the highest risk for hypertension.