[The relationship between physical activity and incident hypertension in rural Chinese]

Objective: To investigate the relationship between physical activity (PA) and the risk of incident hypertension among population in rural areas of China. Methods: The Community Intervention of Metabolic Syndrome in China & Chinese Family Health Study (CIMIC) was conducted in 2007-2008. Data on PA, smoking, drinking, blood pressure and other variables were obtained at baseline. Then the follow-up study of incident hypertension was performed during 2012-2015. A total of 41 457 participants aged ≥18 years and free from hypertension at baseline were included in the final analyses. PA was calculated as metabolic equivalent (MET) for each participant. Cox proportional hazard models were used to explore the relationship of PA with incident hypertension according to the quartiles of PA. Results: A total of 6 780 participants developed hypertension during an average follow up of 5.8 years. The annual incidence of hypertension was 2.80%. Compared to participants in the first quartile of PA, HR (95%CI) of incident hypertension decreased with the level of PA of 0.92 (0.86, 0.99), 0.72 (0.67, 0.77) and 0.70 (0.65, 0.75) for the 2(nd), 3(rd) and 4(th) quartile, respectively (P(trend)<0.001). In subgroup analyses, compared to the first quartile, hazards of hypertension among normotensive participants (systolic blood pressure less than 120 mmHg (1 mmHg=0.133 kPa) and diastolic blood pressure less than 80 mm Hg) in the 2(nd), 3(rd) and 4(th) quartile were 0.82 (0.70, 0.95), 0.73 (0.63, 0.85) and 0.78 (0.67, 0.90), respectively (P(trend)=0.002). Among participants with prehypertension (systolic blood pressure from 120 to 139 mmHg and/or diastolic blood pressure from 80 to 89 mmHg), similar trend for the relationship of PA and incident hypertension was also found with HR (95%CI) of 0.94 (0.87, 1.01), 0.71 (0.65, 0.77) and 0.66 (0.61, 0.71) for the 2(nd), 3(rd) and 4(th) quartile, respectively (P(trend)<0.001). Conclusion: There was linear trend association between PA and incident hypertension. Increased PA in daily life may be a protective factor against hypertension.