Heffernan Kevin S, Baynard Tracy, Goulopoulou Styliani, Giannopoulou Ifigenia, Collier Scott R, Figueroa Arturo, Fernhall Bo
Department of Kinesiology and Community Health University of Illinois at Urbana Champaign Champaign, IL 61820, USA.
Med Sci Sports Exerc. 2005 Dec;37(12):2026-31. doi: 10.1249/01.mss.0000179217.59831.41.
Individuals with Down syndrome (DS) have altered heart rate (HR) and blood pressure (BP) responses to orthostatic challenges and isometric handgrip (IHG) exercise, suggesting possible alteration in baroreflex sensitivity.
This study investigated baroreflex sensitivity (BRS) as a potential mechanism contributing to chronotropic incompetence during IHG in persons with DS.
Heart rate and BP were continually recorded in 12 individuals with DS and 10 controls, at rest and during 2 min of IHG, at 30% of maximal voluntary contraction (MVC). Spontaneous BRS was derived via the sequence method.
No differences were seen in HR at rest between groups. Systolic BP (SBP) was significantly lower in the DS group at rest (106.1+/- 2.9 vs 116.5+/- 3.9 mm Hg, P < 0.05) and during IHG (123.9+/- 4.6 vs 150.1+/- 5.3 mm Hg, P<0.001). A significant group-by-task interaction was found for both change in HR and change in SBP with IHG, because of an attenuated HR and SBP response to IHG in participants with DS (P<0.05). When controlling for resting SBP, the DS group had a lower BRS at rest (16.0+/-1.7 vs 21.2+/-4.2 ms.mm Hg, P< 0.05) and during IHG (7.8 +/-1.0 vs 12.1+/- 2.6 ms.mm Hg, P< 0.05).
Individuals with DS have lower BRS at rest and during IHG than controls and this may be related to their attenuated HR response during perturbation.
唐氏综合征（DS）患者在体位改变和等长握力（IHG）运动时，心率（HR）和血压（BP）反应异常，提示压力反射敏感性可能发生改变。
本研究调查压力反射敏感性（BRS），作为DS患者在IHG运动期间导致变时性功能不全的潜在机制。
连续记录12名DS患者和10名对照者在静息状态以及在最大自主收缩（MVC）的30%进行2分钟IHG运动期间的心率和血压。通过序列法得出自发BRS。
两组静息心率无差异。DS组静息时收缩压（SBP）显著较低（106.1±2.9 vs 116.5±3.9 mmHg，P<0.05），在IHG运动期间也较低（123.9±4.6 vs 150.1±5.3 mmHg，P<0.001）。由于DS患者对IHG运动的HR和SBP反应减弱，发现HR变化和SBP变化与IHG运动之间存在显著的组×任务交互作用（P<0.05）。在控制静息SBP后，DS组静息时BRS较低（16.0±1.7 vs 21.2±4. .2 ms·mmHg，P<0.05），在IHG运动期间也较低（7.8±1.0 vs 12.1±2.6 ms·mmHg，P<0.05）。
DS患者静息时和IHG运动期间的BRS低于对照组，这可能与他们在干扰期间减弱的HR反应有关。
