A few years ago, I wore my Polar F4 heart rate monitor while I did my ashtanga practice just to see how my heart rate responded and how much calories I'd burn. There was this idea that ashtanga will help you lose weight and has some cardiovascular benefits (In what I've read lately, asana practice should not be like exercise otherwise it defeats its purpose).
My knowledge about the body and how it works is based on my training in sports science. Conventional knowledge tells us that in order for us to improve our cardiovascular endurance, we have to train the heart to beat up to a certain rate and maintain that for at least 10 minutes at a time. Below that, the benefits are minimal.
