Blood pressure, cardiorespiratory fitness and body mass: Results from the Tromsø Activity Study

Aims: Modifiable lifestyle factors, as cardiorespiratory fitness (CRF) and body mass, may prevent hypertension.However, it remains unclear whether blood pressure is associated with CRF, independently of body mass index (BMI). Thus, the purpose was to study the relationship between CRF, body composition and blood pressure among 40-44 year old men and women.Methods: During 2007-2008, 12,900 men and women aged 30-85 years attended the sixth survey of the Tromsø study. Blood pressure (mm Hg), height (cm) and weight (kg) were measured and body mass index (BMI kg/m2) was estimated. In a sub-study, the Tromsø Activity Study, CRF [VO2max (ml/kg/min)] was objectively measured using a treadmill test among 313 healthy men and women aged 40-44 years.Results: Among men and women participating in both studies, the mean BMI was 27.1 kg/m2 for men and 25.1 kg/m2 for women. Mean arterial blood pressure (MAP) was 92.4 mm Hg for men and 86.0 mm Hg for women. The proportion defined as pre-hypertensive/hypertensive (systolic/diastolic blood pressure > 120/80) were 33% and 56% for women and men, respectively. The proportion of low, medium and high CRF for both sexes combined differed significantly (p < 0.0001) by BMI level (< 25 or ≥ 25 kg/m2). Increased fitness tended to reduce blood pressure among overweight and obese men (p trend = 0.03), whereas increased fitness tended to reduce blood pressure among normal weighted women (p trend = 0.01).Conclusion: Among healthy 40-44 year old men and women in this study, BMI was positively associated and CRF was negatively associated with blood pressure. Moreover, our results suggest that BMI may be a more important factor than CRF in predicting systolic blood pressure in both sexes. However, cardiorespiratoryfitness and weight control may both be important targets for prevention of hypertension