title: Effect of aerobic training on baroreflex regulation of cardiac and sympathetic function.
abstract: To investigate the effect of aerobic exercise training on baroreflex regulation of muscle sympathetic nerve activity (MSNA) and cardiac R-R intervals in a middle-aged to older population, 10 healthy men > 40 yr of age underwent tests of autonomic function before and after 12 wk of high-intensity training. Cardiac and peripheral baroslopes were determined from the R-R interval vs. mean arterial pressure (MAP) and peroneal MSNA vs. diastolic pressure relationships, respectively, during sequential bolus injections of nitroprusside and phenylephrine. Maximal oxygen uptake increased (P < 0.05) 17% with training. Resting R-R interval increased (881 +/- 23 to 956 +/- 38 ms, P < 0.05), MAP decreased (96 +/- 2 to 91 +/- 3 mmHg, P < 0.05), and MSNA was unaltered (23.1 +/- 2.3 to 23.6 +/- 1.9 bursts/min) with training. Before and after training, respectively, cardiac baroslopes determined with decreasing (8.7 +/- 0.9 to 9.9 +/- 5.5 ms/mmHg) and increasing MAP (9.6 +/- 2.1 to 9.9 +/- 2.2 ms/mmHg) and the peripheral sympathetic baroslope (-3.3 +/- 0.4 to -3.5 +/- 0.6 bursts.min-1 x mmHg-1) did not differ. The results suggest that short-term aerobic training does not alter resting MSNA or neurocirculatory responses to baroreceptor challenges in middle-aged and older men.
authors.affiliation: Department of Medicine, Veterans Administration Medical Center, Milwaukee, Wisconsin.
authors.forename: L M
authors.initials: LM
authors.lastname: Sheldahl
authors.forename: T J
authors.initials: TJ
authors.lastname: Ebert
authors.forename: B
authors.initials: B
authors.lastname: Cox
authors.forename: F E
authors.initials: FE
authors.lastname: Tristani
mesh_terms: D000328:Adult; D000368:Aged; D001341:Autonomic Nervous System / Q000502:physiology; D017704:Baroreflex / Q000187:drug effects / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D015444:Exercise; D005080:Exercise Test; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000294:innervation / Q000502:physiology; D009599:Nitroprusside / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D010806:Physical Education and Training; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*
chemical_list: D009599:Nitroprusside; D010656:Phenylephrine