title: Relationship between muscle sympathetic nerve activity and aortic wave reflection characteristics in aerobic- and resistance-trained subjects.
abstract: OBJECTIVE
  Increased arterial stiffness is associated with an impairment of ventricular-vascular coupling efficiency and increased risk of cardiovascular mortality. Recently, it has been suggested that an increase in arterial stiffness is associated with resistance exercise training. Therefore, the aims of this study were to compare augmentation index (AIx) and left ventricular wasted pressure energy (LVEW) as markers of arterial stiffness and ventricular-vascular coupling efficiency in young aerobic-trained (AT) and resistance (RT)-trained subjects. We also investigated the relationship of muscle sympathetic nerve activity (MSNA) and flow-mediated dilation (FMD) to AIx in both sets of subjects to determine if endothelial function or sympathetic outflow could explain any differences in arterial stiffness.
  
  
  METHODS
  To achieve our aims, we measured MSNA in 15 male subjects (8 RT, 7 AT) using microneurography. We also used applanation tonometry of the radial pressure waveform to noninvasively synthesize aortic pressure waveforms. FMD was calculated as percent dilation of the radial artery from baseline following a 5 min occlusion.
  
  
  RESULTS
  RT subjects had an increased AIx (12 ± 3 vs. -7 ± 2; P < 0.01), LVEW (429 ± 111 vs. -360 ± 77; P < 0.01) and MSNA burst incidence (34 ± 4 vs. 26 ± 4; P < 0.01) when compared with AT subjects. There was no difference in FMD between groups. MSNA burst incidence was also significantly related to AIx in subjects (R (2) = 0.61; P < 0.01) with a distinct demarcation between RT and AT subjects.
  
  
  CONCLUSIONS
  These results confirm previous reports of a positive association between MSNA and AIx in young male resistance-trained subjects. Furthermore, RT is associated with increased arterial stiffness and elevated sympathetic outflow.
authors.affiliation: Kinesiology, California State University, Chico, Chico, CA, USA.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Smith
authors.affiliation: Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, OH, USA.
authors.forename: C A Tony
authors.initials: CA
authors.lastname: Buffington
authors.affiliation: Veterinary Biosciences, The Ohio State University College of Veterinary Medicine, Columbus, OH, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Hamlin
authors.affiliation: Kinesiology Program, Department of Human Sciences, and Department of Physiology and Cell Biology, The Ohio State University, A50 PAES Building 305 West 17th Avenue, Columbus, OH, 43210-1224, USA. devor.3@osu.edu.
authors.forename: Steven T
authors.initials: ST
authors.lastname: Devor
mesh_terms: D000293:Adolescent; D000328:Adult; D001011:Aorta / Q000502:physiology*; D016022:Case-Control Studies; D006801:Humans; D008297:Male; D010543:Peroneal Nerve / Q000502:physiology; D055070:Resistance Training / Q000009:adverse effects*; D013564:Sympathetic Nervous System / Q000502:physiology*; D059289:Vascular Stiffness; D014664:Vasodilation
keywords: Arterial tone; Augmentation index; Blood pressure; Exercise; Sympathetic nerve activity