Interaction between leptin and leisure-time physical activity and development of hypertension

Abstract

Objective. The mechanisms by which overweight and physical inactivity lead to hypertension are complex. Leptin, an adipocyte-derived hormone, has been linked with hypertension. We wanted to investigate the relationship between leptin, physical activity and new-onset hypertension. Methods. The study was a prospective cohort study of 744 women and 367 men, who were normotensive in the third Copenhagen City Heart Study (CCHS) examination, performed 1991–94. Based on questionnaire items, the participants were divided into two groups with low (n = 674) and high (n = 437) levels of leisure-time physical activity, respectively. Results. Between the third and the fourth CCHS examination, performed 2001–03, 304 had developed hypertension, defined as systolic blood pressure (SBP) ≥ 140 mmHg or diastolic blood pressure (DBP) ≥ 90 mmHg or use of antihypertensive medication. In a logistic regression model, including age, sex, body mass index, SBP, DBP, level of physical activity and leptin, we found a significant interaction between leptin and level of physical activity with new-onset hypertension as outcome variable (p = 0.012). When we entered the interaction variables, effect of leptin with low level of physical activity and with high level of physical activity, respectively, in the original model, leptin predicted new-onset hypertension in participants with low level of physical activity [odds ratio (95% confidence interval): 1.16 (1.01–1.33) for one unit increase in log-transformed leptin levels, p = 0.038], but not in participants with high level of physical activity [0.88 (0.74–1.05), p = 0.15]. Conclusion. We found that leptin predicted new-onset hypertension but only in participants with low level of physical activity.