Most yoga research touts mental and physical health benefits from 1 to 6 months of consistent yoga practice. Much less is known about the immediate effects of a single yoga class on these outcomes. Our lab is among the first to investigate this question of whether changes in health markers previously shown to improve with long term practice, are also evident after a single class. To answer this question, we enrolled 30 yoga practitioners and measured blood pressure, cholesterol, blood glucose, and vascular markers before and after participants completed a strenuous, 1-hour vinyasa yoga session.
We chose vinyasa because this style of yoga has little scientific evidence of its healthful effects in comparison to other styles like Bikram, Iyengar, and Ashtanga for which there's more research. We measured augmentation index and pulse wave velocity, two vascular measures indicative of arterial stiffness, which is a predecessor of heart disease, before and after participants completed the "Strong Vinyasa Flow Yoga for Strength and Stamina with Jenni Rawlings" DVD. They practiced in our yoga room at Texas State University (or in the lab on certain days).
We used the forest routine module which includes chair, triangle, side angle, cobra, head stand, numerous vinyasas as well as other poses. Most participants did all postures but a few decided not to attempt the headstands. My grad student selected this challenging DVD and after having done it myself, I can attest to how challenging it is, especially for those like myself who are new to the vinyasa world. We also had participants complete a survey, the PANAS, which asks questions about positive and negative emotions resulting in scores for negative and positive affect. We added this psychological measure because mental states can affect blood vessel function and negative emotions can cause the blood vessels to constrict, which would have influenced our vascular measures.
Our results showed a significant 6% drop in augmentation index, an indirect measure of the stiffness of the arteries, immediately after the 1-hour yoga session. Non-HDL cholesterol and negative affect (reflecting fear, anger, sadness, and other emotions) also declined after the yoga routine. Interestingly, a correlation showed that those with more yoga experience showed more a decrease in negative affect after the session.
Augmentation index is a measure of the pressure wave ejected by the heart in addition to the reflected wave from the peripheral vessels. In people with stiff arteries, the reflected pressure wave occurs earlier and the collision between the two increases the augmentation pressure. This indirect measure of systemic arterial stiffness was reduced after the yoga routine, but the direct measure of aortic stiffness was unaltered. I think this is likely due to yoga postures acutely increasing blood flow and dilation of the vessels supplying the working muscles in the postures with oxygen and nutrient-rich blood. It is typical of exercise to observe sustained vasodilation in the working muscles after the exercise is discontinued.
The reduction in negative emotions could also have contributed to the vascular effect. Research has shown that mental distress suppresses nitric oxide production making the arteries less able to dilate. Thus, the reduction in anger for instance after the yoga session likely liberated more nitric oxide which would lower arterial stiffness. The individual results from cholesterol varied greatly with some showing increased good cholesterol after the session and others showing decreased bad cholesterol. Nonetheless, we did find a statistically significant reduction in non-HDL cholesterol which includes LDL and other lipids that contribute to heart disease.
As a novice practitioner of vinyasa yoga myself (still trying to hold crow pose longer than 1 second), I'm encouraged by these findings. We may continue to focus on vinyasa after our new pranayama research. I'll keep you posted.
Piña A, Shadiow J, Fadeyi AT, Chavez A, Hunter SD. The acute effects of vinyasa flow yoga on vascular function, lipid and glucose concentrations, and mood. Complement Ther Med. In Press.