The Effect of Bikram Yoga on Arterial Stiffness and Endothelial Function in Middle-Aged Adults
Condition: Aging
Study type: Interventional

Summary: 
      Arterial stiffening and endothelial dysfunction are correlates of advancing age contributing
      to the decline in cardioprotection with age. Arterial stiffness and endothelial dysfunction
      are emerging risk factors for cardiovascular disease and predict future cardiac events.
      Vascular function has long been a target for lifestyle interventions with several studies
      showing improvements traditional exercise modes. However, the impact of yoga on vascular
      function remains elusive. This study will determine the effect of a 12-week Bikram yoga
      intervention on arterial stiffness and endothelial function in healthy, middle-aged adults.

      The overall aim of this study is to determine the efficacy of Bikram yoga in improving
      vascular endothelial function and arterial distensibility in middle-aged adults with risk
      factors for coronary artery disease and to determine whether the heated environment plays a
      role in mediating these alterations in vascular function. The investigators propose to
      conduct a 12-week Bikram yoga intervention study in sedentary individuals in order to test
      the following hypotheses:

        1. Bikram yoga will elicit reductions in arterial stiffness and enhancements in endothelial
           function in sedentary, middle-aged adults.

        2. The postulated effects of Bikram yoga will be greater when practiced in a heated
           environment.
    

Detailed description: 
      Bikram yoga is a trademarked form of yoga in which a series of 26 yoga postures are performed
      in a heated (41ºC), humidified environment over a 90-minute period. Bikram yoga has rapidly
      gained popularity with approximately 300 studios currently operating in the U.S. The
      90-minute session consists of pranayama (breathing), and standing, balancing, strengthening,
      and stretching asanas (postures) all performed in a sauna-like environment. Although this
      highly controlled style of yoga provides an optimal choice for interventional research
      studies, few studies have attempted to elucidate the health benefits associated with Bikram
      yoga.

      Subjects will be randomly assigned to one of three groups: heated Bikram yoga (41ºC), room
      temperature Bikram yoga (22ºC), or control in which the participants will be instructed not
      to alter physical activity patterns. Collected data from this interventional study will be
      analyzed by ANOVA and/or ANCOVA with repeated measures. Pearson correlation coefficients will
      be used to examine associations between variables of interest. A significance level of p<0.05
      will be employed to determine statistical significance.

      A total of 80 sedentary (<2 days of physical activity weekly) male and female adults between
      the ages of 40 and 60 years will be recruited and studied. Twenty subjects in each group will
      complete 12 weeks of Bikram yoga at room temperature (22ºC), Bikram yoga in a heated
      environment (41ºC), or a control period during which participants will be instructed not to
      alter physical activity levels. Based on a previous study competed by the investigators which
      employed Bikram yoga as an intervention, a dropout rate of 25% is anticipated. Therefore, as
      the goal of the investigators is to have a minimum of 60 subjects (20 per group) complete the
      12-week intervention, the investigators will recruit and enroll 80 subjects.

      Once participants report to the laboratory, height and weight will be measured and a finger
      prick will be performed. Body composition will then be measured via dual energy x-ray
      absorptiometry scan.

      Endothelial function will be measured non-invasively via flow-mediated dilation. This
      technique involves ultrasound imaging of the upper arm to obtain an image of the brachial
      artery. Once baseline images are acquired, a cuff placed around the forearm will be inflated
      for 5 minutes. More images will be acquired after the cuff is deflated and the images will be
      analyzed to determine the percent change in arterial diameter from baseline.

      Arterial stiffness will be measured using pulse wave velocity. Tonometric sensors will be
      placed on the carotid and femoral pulse sites and blood pressure cuffs placed on the arms and
      ankles to determine brachial and tibial arterial blood pressure. The distance between the
      carotid and femoral pulse sites will be measured and pulse wave velocity will be determined
      as distance traveled divided by the time between the initiation of the carotid and femoral
      pulses.
    

Intervention name(s): Hot yoga; Non-heated yoga
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Subjects in the two intervention groups will complete the standard 26-posture Bikram yoga series in a studio heated at 41ºC (traditional environment) or in a studio at a room temperature of 22ºC whereas control group subjects will be instructed to maintain physical activity patterns for the 12-week study duration. Yoga classes will be held at the Pure Bikram Yoga downtown Austin location. Classes will be completed 3 times weekly for 12 weeks and consist of 90 minutes of yoga postures and breathing exercises.; Subjects in the two intervention groups will complete the standard 26-posture Bikram yoga series in a studio heated at 41ºC (traditional environment) or in a studio at a room temperature of 22ºC whereas control group subjects will be instructed to maintain physical activity patterns for the 12-week study duration. Yoga classes will be held at the Pure Bikram Yoga downtown Austin location. Classes will be completed 3 times weekly for 12 weeks and consist of 90 minutes of yoga postures and breathing exercises.
Other intervention name(s): Bikram yoga
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Prevention