Background: Modifying risk factors to delay or prevent hypertension is critical for subsequent cardiovascular risk reduction. Therefore, understanding the independent and joint associations between cardiorespiratory fitness, obesity, and systolic blood pressure (SBP) is of major significance. In this study, we assessed the relative contribution of body mass index (BMI) and cardiorespiratory fitness to SBP in a large, healthy population.
Methods: Blood pressure, BMI, and cardiorespiratory fitness were measured in 35,061 patients seen for a preventive health examination (1990 to present). BMI was treated as a continuous variable and categorized into sex-specific quartiles. Cardiorespiratory fitness was defined as time achieved during maximal exercise testing and categorized into age- and sex-adjusted quintiles. Generalized linear models were used to determine the independent contribution of fitness and BMI on systolic blood pressure estimates.
Results: The study group was predominately white men (69%) with an average age of 46 years. Normal-weight subjects had a mean SBP 12 mm Hg lower than in the obese (115 vs 127 mm Hg, P < .001), while being high- fit was associated 6 mm Hg difference in mean SBP comparing the highest and lowest fitness quintile (119 vs 125 mm Hg, P < .001). Normal-weight individuals with a cardiorespiratory fitness level greater than the first quintile (Q1) had the lowest mean SBP (P < .001). Both BMI and cardiorespiratory fitness were associated with SBP (P < .001 for both); however, when assessed simultaneously, BMI had a greater impact on SBP estimates than fitness.
Conclusion: When comparing lifestyle risk factors BMI and cardiorespiratory fitness, BMI was a more important factor in predicting SBP. Importantly, only modest fitness levels among normal-weight individuals were associated with the lowest systolic blood pressure estimates.
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