title: Accumulation of physical activity leads to a greater blood pressure reduction than a single continuous session, in prehypertension.
abstract: BACKGROUND
  Despite limited research, the accumulation of physical activity has been recommended for the treatment of prehypertension.
  
  
  OBJECTIVE
  To compare the duration and magnitude of blood pressure reduction after accumulated physical activity with that after a single session of continuous physical activity, and to investigate sympathetic modulation as a possible mechanism for the reduction in blood pressure after each acute session.
  
  
  METHODS
  Prehypertensive adults (n = 21) participated in a randomized crossover design. Ambulatory blood pressure and heart rate variability (Holter monitoring) were measured for 12 h after accumulated physical activity (4 x 10-min walks (1/h for 4 h) at 50% of VO2peak), continuous physical activity (40-min walk at 50% of VO2peak) and control treatments. Blood pressure and heart rate variability after each activity treatment were compared with the respective periods from the control treatment. Heart rate variability was correlated with reduction in blood pressure.
  
  
  RESULTS
  Systolic blood pressure (SBP) was reduced for 11 h after accumulated physical activity (P < 0.01), and for 7 h after continuous physical activity (P < 0.05). Diastolic blood pressure (DBP) was reduced for 10 h after accumulated physical activity (P < 0.05) and for 7 h after continuous physical activity (P < 0.05). With accumulated physical activity, the differences in normalized low-frequency (r = 0.517, P < 0.01) and high-frequency (r = -0.503, P < 0.05) power were correlated with reduction in SBP and the differences in normalized low-frequency (r = 0.745, P < 0.001), high-frequency (r = -0.738, P < 0.001) powers, and low frequency: high frequency ratio (r = 0.756, P < 0.001) were correlated with reduction in DBP. With continuous physical activity, the difference in low frequency: high frequency ratio (r = 0.543, P < 0.05) was correlated with reduction in DBP.
  
  
  CONCLUSIONS
  The accumulation of physical activity appears to be more effective than a single continuous session in the management of prehypertension. Sympathetic modulation was associated with reduced blood pressure after each session.
authors.affiliation: Clinical Exercise Physiology Laboratory, Department of Kinesiology, Indiana University, Bloomington, IN 47405, USA.
authors.forename: Saejong
authors.initials: S
authors.lastname: Park
authors.forename: Lawrence D
authors.initials: LD
authors.lastname: Rink
authors.forename: Janet P
authors.initials: JP
authors.lastname: Wallace
mesh_terms: D000328:Adult; D001794:Blood Pressure; D001795:Blood Pressure Determination; D018660:Blood Pressure Monitoring, Ambulatory; D018592:Cross-Over Studies; D015444:Exercise; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D013997:Time Factors