title: Cardiorespiratory fitness, BMI, and risk of hypertension: the HYPGENE study.
abstract: BACKGROUND
  Cardiorespiratory fitness and regular physical activity are inversely associated with the risk of hypertension, and exercise training has been shown to lower elevated blood pressure (BP). Genetic factors contribute significantly to the interindividual differences in endurance training-induced changes in BP. However, similar data on the genotype-by-fitness interactions on the risk of hypertension are scarce.
  
  
  METHODS
  In 2000, we started a systematic collection of blood samples from all consenting subjects of the Aerobics Center Longitudinal Study (ACLS) with a goal to generate a resource for studies addressing genotype-by-fitness interaction effects on various health-related end points. Here, we introduce the rationale and design of the first study based on the ACLS genetics resource focusing on hypertension as the health outcome (HYPGENE study), and we report the associations of cardiorespiratory fitness and body mass index (BMI) with the risk of hypertension. All HYPGENE subjects (N = 1234) were healthy and normotensive at their first clinic visit. Cases (N = 629) developed hypertension during the follow-up period (mean 8.7 yr), whereas controls (N = 605) remained normotensive (mean follow-up 10.1 yr).
  
  
  RESULTS
  Cardiorespiratory fitness was the strongest predictor of the hypertension risk, with each maximal metabolic equivalent unit being associated with a 19% lower risk (95% confidence interval [95% CI], 12-24%). Each baseline BMI unit was associated with a 9% higher hypertension risk (95% CI, 4-13%). However, the association of BMI was greatly attenuated (odds ratio 1.04 [95% CI, 0.99-1.09]) when fitness also was included in the model.
  
  
  CONCLUSIONS
  The HYPGENE study will provide an excellent resource to address hypotheses regarding the genetic basis of hypertension while taking cardiorespiratory fitness level into account.
authors.affiliation: Human Genomics Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA. rankint@pbrc.edu
authors.forename: Tuomo
authors.initials: T
authors.lastname: Rankinen
authors.forename: Timothy S
authors.initials: TS
authors.lastname: Church
authors.forename: Treva
authors.initials: T
authors.lastname: Rice
authors.forename: Claude
authors.initials: C
authors.lastname: Bouchard
authors.forename: Steven N
authors.initials: SN
authors.lastname: Blair
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002319:Cardiovascular System; D016022:Case-Control Studies; D016021:Epidemiologic Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000209:etiology / Q000235:genetics*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010809:Physical Fitness / Q000502:physiology*; D018570:Risk Assessment; D013781:Texas / Q000453:epidemiology