The Effects of Stretching Training on Arterial Function and Autonomic Control
Condition: Obesity; Pre-hypertension; Hypertension
MeSH terms: Hypertension; Prehypertension
Study type: Interventional

Summary: 
      Hypertension is a major risk factor for cardiovascular disease. Hypertension and abdominal
      obesity are associated with dysfunction of the main mechanisms of cardiovascular regulation,
      the autonomic nervous system and the vascular endothelium. Increased sympathetic activity and
      endothelial dysfunction are associated with increased arterial stiffness, which is an
      independent risk factor for the development of hypertension and other cardiovascular
      diseases. The recommended intervention for controlling BP in pre- and stage 1- hypertensive
      individuals is lifestyle modifications such as exercise, and not drug therapy.Although
      aerobic and resistance exercise has been shown to be beneficial for the cardiovascular
      system, special populations such as the elderly and obese may have physical and/or
      musculoskeletal limitations which may limit their participation in these exercise modalities.

      Stretching is a form of exercise that is widely recommended for injury prevention. Among the
      benefits of stretching are an increased flexibility, enhanced muscular coordination, stress
      relief, improved range of motion and an improved posture. Previous studies have shown
      stretching training to increase arterial compliance and acutely increase sympathetic nerve
      activity. In addition, low flexibility levels have been found to be associated with arterial
      stiffness. Given that stretching of skeletal muscle causes an increase in sympathetic nerve
      activity; repetitive stimulation of sympathetic activity induced by habitual stretching,
      might chronically reduce resting sympathetic activity. The reduction in sympathetic activity
      might result in a decrease of arterial stiffness and blood pressure.

      The investigators hypothesis is that 8 weeks of stretching training would reduce arterial
      stiffness, blood pressure and sympathetic activity in obese women. The investigators also
      hypothesize that the improved arterial function with stretching would be associated with
      increases in flexibility levels.
    

Detailed description: 
      The purpose of this study is to examine the effects of 8 weeks of stretching training on
      blood pressure,arterial stiffness, wave reflection, endothelial function and cardiovascular
      autonomic control. The specific aim of the study is:

      - To evaluate the effects of 8 weeks of ST on arterial function and aortic hemodynamics by
      assessing arterial stiffness (aortic, systemic, and leg), aortic blood pressure and wave
      reflection, and autonomic function (heart rate variability, vascular sympathetic activity
      [low-frequency power of systolic BP variability], and baroreflex sensitivity)
    

Intervention name(s): Stretching Training
Intervention type(s): Other
Intervention description(s): The stretching training intervention consists of 38 whole-body stretching exercises, 3 times per week for 8 wk. Each stretch will be held in place for 30 seconds, with a 15 seconds of rest in between stretches.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: prehypertension; hypertension; obesity; stretching; arterial function; arterial stiffness; pulse wave velocity; autonomic function; endothelial function