As I mentioned in the previous post, I wanted to observe how my heart rate responds to a basic ashtanga practice. One of the many definitions of yoga is integration. Thus, allow me to integrate what I've learned from grad school in answering my question.
Methodology
The subject was a 34 year old Asian male who had been practicing ashtanga yoga regularly for more than 5 years. The subject has normal BMI (22.0), resting heart rate of 60 bpm, and an estimated VO2max of 37mL/kg/min. The subject reported no other moderate-to-vigorous physical activities except for ashtanga which he performs 60-120 minutes of ashtanga yoga 3-4 times a week. Recommended age-predicted training heart rate for the subject is 112bpm-167bpm. Based on heart rate reserve, his recommended training heart rate is 123bpm-167bpm.
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.
Culminating activity of all dance and movement-based classes at the
University of the Philippines Diliman
College of Human Kinetics
General Physical Education Program.
March 2010.
Uploaded on youtube by Prof. Mynette Aguilar.
***
I wore my Polar F4 heart rate (HR) monitor during practice this morning to record exercise HR. Resting heart rate (RHR) for this morning was above average at 68 beats per minute (bpm) but high based on my past RHR. The last time I checked it was 56 bpm. The average resting heart rate for men my age is between 71 to 74 bpm (Topend Sports, 2010).
With the RHR, I computed my HR training zone using Karvonen formula. Calculated training zones at 50-85% maximum HR is 129-172 bpm. I updated the user setting of my HR monitor and it was ready to go.
Here is the summary:
Duration: 35.08 minutes
In zone: 0 minutes
Average HR: 92 bpm
Max HR: 123 bpm
Calories: 120 kcal
I did a basic practice which includes 5 surya A, 5 surya B, padangusthasana, padahasthasana, trikonasana A and B, parsvakonasana A and modified B, prasaritta padottanasana ABCD, parsvottanasana, uttitha hasta padangusthasana ABC, ardha baddha padmottanasana, utkatasana, virabadhrasana A and B, paschimattanasana A and C, purvottanasana, and the last three closing poses, yogamudrasana, padmasana, and utpluthih.
I turned on the HR monitor 10 seconds before I started the first surya A while standing in tadasana, and turned it off 5 seconds after landing from the last jump through, before savasana.
What does this tell us?
Because the data showed that no time was spent within the target training zone, we can say that the intensity of the basic program is not high enough to reach cardiovascular level, at least for me. I'm fairly fit and I've been doing this for a long time. Plus I was focusing on my breathing and regulating it consciously.
The story might be different for someone who is sedentary and has been active for a while.
I believe it is possible though to raise the heart rate up to at least 50% of my THR if I would jump higher and contract my big muscle groups more. In that case, however, I will be doing exercise and not yoga asanas.
