title: Twenty-four hour, ambulatory blood pressure responses following acute exercise: impact of exercise intensity.
abstract: OBJECTIVE
  Mild to moderate acute, endurance exercise has generally been shown to reduce blood pressure (BP) in hypertensive (HT) individuals. Whether a slightly more strenuous bout of exercise can elicit a greater and more prolonged BP reduction is unknown. Therefore, the purpose of this study was to examine the effects of two, 30-min exercise bouts, conducted at 50% and 75% of maximal oxygen uptake (VO2max), on the quantity and quality of BP reduction over a 24-h period.
  
  
  METHODS
  Sixteen, Stage 1 and 2 non-medicated, HT (8 men/8 women) subjects were matched with normotensive (NT) men and women (n = 16). All subjects were evaluated for VO2max with a symptom-limited treadmill test and then completed a 30-min exercise bout at 50% and 75% of VO2max as well as a control (no exercise) session in random fashion on separate days. Twenty-four hour ambulatory BPs were measured after both the exercise and control settings. Data was assessed at 1, 3, 6, 12, and 24 h post-exercise and control session.
  
  
  RESULTS
  A repeated-measures ANOVA showed non-significant differences between HT men and women and that both exercise intensities, relative to the control session, significantly (P<0.05) reduced systolic (S) and diastolic (D) BPs. NT subjects showed non-significant reductions following both intensities. The reductions in the HT men and women averaged 4 and 9 mm Hg (SBP)/5 and 7 mm Hg (DBP) for 50% and 75%, respectively. On average, the HT subjects (men and women combined) maintained significant SBP reductions for 13 h after the 75% bout compared to 4 h after the 50% intensity. Likewise, DBP was reduced for an average of 11 h following the 75% bout compared to 4 h after the 50% intensity.
  
  
  CONCLUSIONS
  These results suggest that an exercise bout conducted between 50-75% VO2max significantly decreases SBP and DBP in HT subjects and that a greater and longer-lasting absolute reduction is evident following a 75% of maximum bout of exercise.
authors.affiliation: University of New Hampshire Department of Kinesiology, Durham, NH 03824, USA. tjq@christa.unh.edu
authors.forename: T J
authors.initials: TJ
authors.lastname: Quinn
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D001835:Body Weight; D016022:Case-Control Studies; D002940:Circadian Rhythm / Q000502:physiology*; D003971:Diastole; D004032:Diet; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology; D012016:Reference Values; D013599:Systole