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
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
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
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.
- 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.
- 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
- 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
- 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