title: Cardiac autonomic function and baroreflex changes following 4 weeks of resistance versus aerobic training in individuals with pre-hypertension.
abstract: OBJECTIVE
  Cardiac autonomic modulation and baroreflex sensitivity (BRS) are altered in individuals with hypertension. Aerobic exercise (AE) training has been shown to improve both measures, yet little is known about the effects of resistance exercise (RE). The purpose of this study was to examine the heart rate variability (HRV) and BRS following 4 weeks of resistance or aerobic training in a population with borderline high blood pressure (BP).
  
  
  METHODS
  Twenty-nine mild hypertensives were recruited and randomly assigned to 4 weeks of RE or AE training. Before and after training, resting measures of HRV frequencies and BRS were obtained.
  
  
  RESULTS
  There was a significant decrease in resting systolic BP for both exercise training modes (RE 136 +/- 3.0 pre- to 132 +/- 3.4 post-training vs. AE 142 +/- 4.0 pre- to 137 +/- 3.6 mmHg post-training, P = 0.019). Diastolic BP decreased significantly following both exercise training modes (RE 78 +/- 1.31 pre to 74 +/- 1.1 post vs. AE 80 +/- 1.7 pre to 77 +/- 1.6 mmHg post, P = 0.002). A significant time by training mode interaction for low frequency : high frequency (HF) ratio (P = 0.017) with AE decreasing the ratio (275.21 +/- 67.28 to 161.26 +/- 61.49) and RE increasing this ratio (143.73 +/- 65.00 to 227.83 +/- 59.41). Natural log-transformed (ln) HRV values showed a time-by-training mode interaction for ln HF (P = 0.05) as ln HF increased (4.7 +/- 0.38 to 5.4 +/- 0.35 ms(2)) following AE and decreased (5.98 +/- 0.37 to 5.76 +/- 0.42 ms(2)) following RE. BRS increased following aerobic training and decreased after resistance training (6.74 +/- 1.2 to 7.94 +/- 1.3 and 10.44 +/- 1.2 to 9.1 +/- 1.2 ms mmHg(-1) respectively, P = 0.021).
  
  
  CONCLUSIONS
  Aerobic exercise improved the autonomic nervous system (increasing vagal tone, reducing sympathovagal balance while increasing BRS) while RE showed no improvements in cardiac autonomic tone and decreased BRS.
authors.affiliation: Department of Exercise Science, Syracuse University, 820 Comstock Avenue, Syracuse, NY 13244, USA. sccollie@syr.edu
authors.forename: S R
authors.initials: SR
authors.lastname: Collier
authors.forename: J A
authors.initials: JA
authors.lastname: Kanaley
authors.forename: R
authors.initials: R
authors.lastname: Carhart
authors.forename: V
authors.initials: V
authors.lastname: Frechette
authors.forename: M M
authors.initials: MM
authors.lastname: Tobin
authors.forename: N
authors.initials: N
authors.lastname: Bennett
authors.forename: A N
authors.initials: AN
authors.lastname: Luckenbaugh
authors.forename: B
authors.initials: B
authors.lastname: Fernhall
mesh_terms: D000328:Adult; D000886:Anthropometry / Q000379:methods; D001341:Autonomic Nervous System / Q000503:physiopathology; D017704:Baroreflex / Q000502:physiology*; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology / Q000534:rehabilitation*; D008297:Male; D008875:Middle Aged; D055070:Resistance Training / Q000379:methods; D016896:Treatment Outcome