title: Effects on blood pressure and autonomic nervous system function of a 12-week exercise or exercise plus DASH-diet intervention in individuals with elevated blood pressure.
abstract: OBJECTIVE
  Hypertension is related to abnormalities in autonomic nervous system (ANS) function, with increased sympathetic output and decreased parasympathetic tone. Lifestyle interventions are the first line of treatment in hypertension, and decreased blood pressure (BP) effects may be related to changes in ANS function. Using heart rate recovery (HRR) from exercise as an index of parasympathetic tone and plasma noradrenaline as an index of sympathetic tone, we investigated the effects of lifestyle interventions on ANS function in patients with elevated BP.
  
  
  METHODS
  Sedentary participants with elevated BP were randomly assigned to either an exercise only (N = 25), exercise plus dietary approaches to stop hypertension (DASH) diet (N = 12), or waitlist control (N = 15) 12-week intervention. Plasma noradrenaline was measured at rest and participants performed a peak exercise test before and after the intervention. HRR was calculated as peak heart rate (HR) minus HR at 1 min post-exercise.
  
  
  RESULTS
  Heart rate recovery showed a significant group by time interaction; both intervention groups showed increases in HRR from pre- to post-intervention, while waitlist showed no change. Similarly, both exercise plus diet and exercise groups, but not waitlist, showed significant reductions in BP from pre- to post-intervention. Linear regression revealed that BP post-intervention was significantly predicted by change in HRR when controlling for pre-BP, age, gender and BMI.
  
  
  CONCLUSIONS
  Lifestyle interventions induced training-reduced BP and altered autonomic tone, indexed by HRR. This study indicates the importance of behavioural modification in hypertension and that increased parasympathetic function is associated with success in reduction of BP.
authors.affiliation: University of Sydney, Exercise Health and Performance Research Group, Lidcombe, Australia. kate.edwards@sydney.edu.au
authors.forename: K M
authors.initials: KM
authors.lastname: Edwards
authors.forename: K L
authors.initials: KL
authors.lastname: Wilson
authors.forename: J
authors.initials: J
authors.lastname: Sadja
authors.forename: M G
authors.initials: MG
authors.lastname: Ziegler
authors.forename: P J
authors.initials: PJ
authors.lastname: Mills
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001341:Autonomic Nervous System / Q000378:metabolism / Q000503:physiopathology*; D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D002140:California; D003131:Combined Modality Therapy; D005080:Exercise Test; D005081:Exercise Therapy; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000178:diet therapy / Q000503:physiopathology / Q000628:therapy*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D020127:Recovery of Function; D040242:Risk Reduction Behavior; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D009638:Norepinephrine