Yoga makes a lot of claims pertaining to its benefits for your health. There are numerous ways in which practicing yoga changes the physiology of your body and mind. There are also a few claims made by the yoga community that need to be viewed through the filter of human anatomy. A broad claim such as “Yoga increases your metabolism” is true in most regards but does not apply to all styles of yoga. It is the goal of these articles to provide a greater understanding of our own bodies’ anatomy and physiology, and how we can use this information to develop and deepen our personal yoga practices and our experiences in our own bodies.
Let’s come back to the claim that “Yoga increases your metabolism”. A more accurate statement would be “Dynamic yoga increases your metabolism”. The truth emerges from examining yoga’s effects on the different branches of our nervous system. Any physical exercise that increases our heart rate and our rate of respiration engages the sympathetic nervous system. Conversely, any type of relaxing that slows down our heart rate and our breathing rate engages the parasympathetic nervous system. When we are in a state of sympathetic dominance, our metabolic rate increases. We are more active so our bodies begin to break down stored fats to retrieve the energy needed to meet the demands we are placing on our bodies. Active styles of yoga such as ashtanga, vinyasa, kundalini, and shivananda engage our muscles, increase our heart rates and breathing, and stimulate this sympathetic dominance of the nervous system. At this point it seems like yoga does indeed increase our metabolism.
But let’s not forget that there are styles of yoga that are all about relaxation. In restorative yoga, the goal is to have no muscular engagement. We use props such as bolsters and blocks to create support for our bodies so that we don’t have to use our muscles to maintain a comfortable position. In yin yoga we aim for minimal muscular engagement (in many poses none at all) so that our connective tissues get a healthy stretch and our bones are compressed to stimulate reformation. Both of these styles lower our heart rates and slow down our breath, thus engaging the parasympathetic nervous system. While the parasympathetic nervous system is dominant, metabolism actually decreases as our bodies demand less energy because we are less active.
So that means not all yoga increases our metabolism right? Exactly. If we were to only practice restorative styles of yoga we would spend more time in parasympathetic dominance where our metabolism is lower. Active forms of yoga increase our metabolism. Passive forms of yoga decrease our metabolism. Thus the statement “Dynamic yoga increases your metabolism” is a more accurate claim.
This series of articles will provide a framework to understanding the anatomical systems of our bodies. To explore how yoga correlates to our experience in our bodies we will examine the physiology of our bodies in different types of yoga postures. By understanding the composition and inner workings of your body you can begin to apply that knowledge to developing a personal practice that is most beneficial for your one-of-a-kind body.