The Effect of Bikram Yoga on Arterial Stiffness and Endothelial Function in Middle-Aged Adults



Status:Completed
Conditions:Healthy Studies
Therapuetic Areas:Other
Healthy:No
Age Range:40 - 60
Updated:10/14/2018
Start Date:September 2013
End Date:December 30, 2016

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Bikram Yoga and Vascular Health

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.

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.

Inclusion Criteria:

- 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.

Exclusion Criteria:

- pregnancy (if the subject is unsure about her status, a simple testing kit will be
made available to the subject)

- Uncontrolled hypertension (blood pressure >160/100 mmHg while on hypertensive
medications)

- Infection within the previous 4 weeks

- Having adrenal or endocrine tumors

- Renal disease

- Prior myocardial infarction (heart attack)

- Known coronary artery disease

- Personal history of stroke

- Heart failure

- Cardiac arrhythmias

- Chronic obstructive pulmonary disease

- Personal history of psychosis

- Diabetes

- Having a body mass index ≥35 kg/m2

- Recent chest pain or dyspnea

- Orthopedic limitations that prevent them from being able to perform the yoga postures

- Heat intolerance

- Having undergone a barium test within the previous two weeks

- Having had a nuclear medicine scan or injection with x-ray dye within the previous
week.
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1
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Austin, Texas 78712
Phone: 512-471-8594
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