Saturday, October 1, 2016

Stuff I Learned - Week #4

The Backstory:
I was a pretty good athlete, albeit not a great one. While I harbored dreams of competing at a high level after college, those dreams were grounded on little more than high hopes and fear. I simply did not have the talent to compete at a high level post-collegiately.

By the time that I had graduated from college, I had competed and identified as a high jumper for over seventeen years. The identity of high jumper had became so indelibly woven into my self-concept, that I had little idea of who I was other than that. The thought of letting go of the high jumper identify was petrifying; if not high jumper, then who was I?

In the Exercise Physiology Lab
University of Wisconsin - Madison
By the time that I was facing this identity crisis I had already been practicing yoga for awhile. While I don't remember consciously trading in my high jumper identify for the yogi identity, in hindsight, it would appear as though that is what I did. How convenient - I am a yogi... I still am something/somebody.

All the time & energy that I had thrown into athletics was then channeled into the practice of yoga. I read every book that I could get my hands on, studied with many master teachers, and spent vast hours on my mat.

Around that same time, the yoga community more loudly voiced the various physical benefits of yoga, including the assertion that yoga contributed to cardiovascular health. How convenient, I remember thinking; yoga does it all!

It wasn't until many years later that I let down the solidity of my yogi identify and began to deeply observe how my body and mind actually felt. While there were many, many benefits to those years of intense yoga practice, at a depth level I had come to feel weak and out of shape. Once I softened my attachment to the yogi identity, I was able to objectively gauge the state of my mind and body. And my body had come to feel pretty fragile most of the time. It was time to regain the strength and endurance that I had previously taken for granted!

As a sciencey guy, I decided to quantify my training by tracking my heart rate as I exercised. It was shocking and demoralizing to find how out of shape I had become! My heart rate would rocket beyond the lactate threshold (the body working very hard) when I'd go out for a brisk walk. Forget about running - I'd gotten so far out of shape that it took a full 9-months of daily training before I could even think about jogging.

I chipped away at getting back into shape, and along the way I received daily reminders to accept myself as I was. Judgment would frequently creep in, and by bringing awareness to the judgment (not trying to make it go away, nor buying into the negativity), the judgment and I became good friends on my daily walk/jogs. Slowly, slowly my capacity increased, and one day I felt confident enough to test my VO2 max in an exercise physiology lab. What better way to quantify my fitness levels than in an exercise physiology lab?

In the lab, I found that my methodical approach to training had really payed off, and that my cardiovascular fitness was coming back! VO2 max is considered a good measure of cardiovascular fitness, and for a forty-something guy, mine was within the fit range. Along the way, I had also become incredibly curious about the mechanisms underlying cardiovascular fitness, and the hows and whys of the machines that measured my cardiovascular fitness.

Fast forward a couple of years, and last week I found myself in an exercise physiology lab; only this time, I was learning how to operate the equipment and interpret the data!

The Science:
In last week's lab, I had a chance to learn more about calorimetry, or how energy is consumed during exercise. When our muscles work, they need fuel. There are many types of fuels, though for this preliminary discussion, let's focus on fat and carbohydrate. There are certainly other factors (protein, minerals, nutrients, etc) involved in maintaining optimal health, though for a discussion on exercise, fats and carbohydrates do the heavy lifting. Most of the energy that fuels your bike ride, yoga practice, hike, etc. come from some combination of fat and carbohydrate. How do we measure this energy that's consumed during exercise?

One way to measure the amount of fuel that's burned during exercise is by measuring the volume of oxygen that's consumed while exercising. The amount (volume) of oxygen that is consumed while exercising is proportional to the consumption of energy, or calories. More oxygen consumed, more energy consumed. Less oxygen consumed, less energy consumed.

The air that we breath in (inhale) contains oxygen, and by measuring how much oxygen is in the air that is exhaled, we get a good idea of the amount of oxygen that has been consumed. In the photo, you can see that the test subject (C) was hooked up to a snorkel-like device. This snorkel was connected to a gas analyzer that measured the exact composition of the air that exited his body. By doing so, we were able to accurately quantify the amount of energy that C was consuming.

Not only could we accurately calculate how much total energy C was consuming, but we could also calculate the relative amount of fat and carbohydrate that was being consumed. As fat and carbohydrate are consumed by muscles in slightly different ways, the proportions of respiratory byproducts are slightly different for fat and carbohydrate utilization.

Using some simple formulas, the data from the gas analyzer gave us a very good approximation of the total number of calories that C burned during his workout, and the number of fat calories and carbohydrate calories that were burned.

Now, in itself, this wasn't the most earth shattering result. These relationships are so well known, that pretty-good approximations underly the software of common fitness apps such as Fitbit. When your Fitbit tells you how many calories that you've burned in walking your daily 10,000 steps, the Fitbit is not actually measuring the calories that you've burned. Rather, the Fitbit is calculating calorie consumption by using the formulas that exercise physiologists have found to hold true for most of the people, most of the time.

If this result wasn't all that earth shattering, then why did we do this lab, and why am I writing about it? Analyzing the composition of exhaled air tells us much more than just the amount of energy that's being consumed, and the techniques of this lab were a first-step in measuring VO2 max. And it's VO2 max that gives us a good indication into overall fitness.

In an upcoming blog entry I'll build on this discussion, and describe how analyzing the composition of exhaled air allows us to calculate VO2 max. In the meantime, I'll leave you with a link to an article that describes how yoga builds cardiovascular fitness.

Have a great week!


Reka said...

Thanks for the write up I enjoyed reading it and the article you referenced within.


Lisa Oglesby said...

So, I am curious. With the practice of Yoga and breathing, say for example a student has a very long cycle of the inhale and exhale, using the lungs to their full capacity.. Take this student out jogging, and the student can continue to breath with that same rhythm, however the cycle is shorter, right? This student picks up their pace, breathing becomes more rapid, HOWEVER, due to breathing practice, the exhale is still quite long. Would that indicate the student having a good VO2 max? Is their any correlation?

Thank you for writing what you're discovering, I find it all intriguing.


Scott Anderson said...

While Yoga may have the potential to expand the ribcage and increase thoracic volume, it's unlikely that Yoga and any attendant changes in the breathing will alter VO2 max. Respiratory volume is only a small part of respiratory efficiency.

The VO2 max is not only about the supply of air, but also its utilization. Among the many physiological responses to training are changes in stroke volume of the heart, increased density of capillary beds that surround the muscles, and increased numbers of mitochondria in the muscle tissue, itself. When these changes occur, breathing will naturally shift to supply the needed O2 and remove the CO2.

When running, it's best not to mess with your breathing; rather use the time spent running to meditate on the breathing as it naturally rises and falls. It's an amazing opportunity to witness firsthand the wisdom of the body.