In pursuit of science (my VO2 max test)

It's a testament to the hegemony of the "hard" sciences that the word "scientist" has come to mean something so narrowly defined, usually referring to a chemist, biologist, or someone else who works in a lab, wearing an outfit like this:

Google image search, "Scientist"

Google image search, "Scientist"

I would never call myself a scientist in mixed company (and would add the modifier "social," or avoid the word altogether), but my work is scientific: I ask research questions, I test hypotheses, and I do all kinds of tricks with data. Science is one way, though not the only way, of knowing the world, and a good thing to reach for to get your bearings in a new field. For people like me, running is my entry point into the foreign worlds of anatomy, physiology, physics, biology, and chemistry, and I suspect I'm not alone: What semi-serious runner hasn't lost a few hours reading about "fueling" (elsewhere known as "eating and drinking") or squinting at a photo on the internet of a tendon or bone, wondering, "Is that what the inside of my leg really looks like??"

These feelings of delight and discovery are amplified by the fact that a lot of training is completely counterintuitive (for example, why do speedwork, instead of lots of MP miles?). When I find the answer to a question like that, I experience a such a thrill of understanding in realizing how all of my body parts click together in such a clever way.

This is, I guess, what compelled me to sign up for a research study that would simulate sending me to space. The appeal: I could 1) learn about new research and methods, and 2) do so while collecting data for my running, my very own (navel-gazing, n=1) science project.

The pre-study phase required subjects to do a VO2 max test. And in my enthusiasm and ignorance, I thought it would be "fun." 

Ask anyone who's done a VO2 max test before. It is, by design, a test in which you push your body to its absolute breaking point. While wearing a plastic mask over your face. And with a clothespin clamping your nose shut. If I'd stopped geeking out for even a second about the fun "data" about my cardiovascular system I'd collect, I would have realized that this experience would definitely suck. 

First, I wandered through the halls of the campus hospital, looking for the department devoted to deep-sea diving/space research.

It's amazing how much space exploration and deep-sea diving have in common when you think about it. I think it's so cool that they share a department. I might have missed my calling, research-wise.

The study protocol was really long and took up, in total, four hours. During this time I learned to simulate astronaut tasks, including SPACE WALKS ON MARS, and all about the various decompression challenges in both scuba diving and space travel. Pretty cool fact: you can get decompression sickness ("the bends") from ascending from a depth (as in scuba diving) or from descending from altitude (in space). 

Eventually, it was time for the test. I'll do my best to explain it with the caveat that this is not my field at all. If I miss anything or if I'm saying something crazy/wrong, please let me know!

A VO2 max test measures the maximum rate of oxygen consumption during exercise. The test is usually done on a treadmill or bike. The test has a built in bias that's related to the equipment used: runners tend to score higher on a treadmill than on a bike, likely for the reasons you'd imagine (my guesses: runners may have developed more "mental toughness" for running that they don't have on the bike, muscle fatigue in an unfamiliar sport may make the exercise seem tougher than it really is, etc.) But in general because the test measures oxygen absorption, it doesn't matter how skilled the test-taker is at riding a bike because the test measures only the efficiency of the cardiovascular system.

Where old exercise bikes from the 1980s go to retire.

Where old exercise bikes from the 1980s go to retire.

The test itself took about 17-18 minutes. It started off easy, biking at a low resistance for three minutes. The resistance was upped every 3 minutes until my oxygen reaches some pre-determined threshold, at which point the test administrator began upping the resistance every 1 minute. At each interval, I was asked to rate my effort on a scale of 1-20 by pointing at numbers on a laminated card. At some interval (every minute? Every 30 seconds?) I got a new VO2 reading.

This is not me, but this is the equipment that was on my face. Photo (VIA)

This is not me, but this is the equipment that was on my face. Photo (VIA)

The head thing was pretty uncomfortable, and the nose clip was even more uncomfortable. I was getting over a cold and the room was very dry, so I kept needing to cough into the mouthpiece/tube thing. My throat felt like sandpaper. During the test I wasn't able to drink water, which contributed to that discomfort. 

As the test progressed, I started having that desperate, where-the-F-is-the-finish-line feeling I get toward the end of intense races that tells me I'm about to max out.The machine was taking measurements every 30 seconds or so, and when I felt I wouldn't be able to make it to the next one I stopped, ending the test. But about a minute after I finished, I had recovered enough to be annoyed with myself for not trying to get just one more measurement. (That's always how it goes!)

I will stop here to say that I have no fun graphs to post because I lost the paper with my VO2 results on it. My life is a hot mess of showing our apartment to people who might be able to take over our lease, house renovations, and hosting family for Thanksgiving, and I'm pretty sure it got tossed when we were hurriedly cleaning up to show our apartment to yet another possible renter. I'm bummed because it had some cool graphs with my heart rate, effort, METS, oxygen and CO2 every few minutes. Fortunately, I do remember that my VO2 max was 49.3, and my maximum METS was 14. These numbers mean that I would definitely qualify to be an astronaut (!!!!!!) (This was the purpose of the VO2 max test, to recruit subjects who were similar to the population of astronauts.)

Regarding what to do with this data, the first thing I did was plug it into this ancient spreadsheet I found in the bowels of the internet. It calculates VDOT (Jack Daniels's estimate of VO2max based on race times). My 5k PR of 23:31 produces a VDOT of 41.2. My much more recent half PR from City of Oaks (1:50:32) produced a VDOT of 40.2. 

41.2 & 40.2 are a ways off of my VO2 max, 49.3, 

Next, I calculated backwards to find what race times are associated with a VDOT of 49.3.

  • Marathon: 3:13
  • Half marathon: 1:32
  • 10k: 42:00
  • 5k: 20:00

Obviously, these are very, very far off from my PRs!

So what gives? Why do my race times produce VDOTs that are so different from my VO2 max? Why does my VO2 max map on to race PRs that are lightyears away from my actual race times? These are rhetorical questions -- I can't even begin to attempt to answer these now. I'm still doing some reading to try to figure out the extent to which VO2 max should be thought of a predictor of running fitness vs. potential, and whether or how to use this number in Tobacco Road training. Unfortunately, because I was doing this for a study rather than as part of a consultation with an exercise physiologist, I am kind of own my own in finding answers to these questions. I'm not going to guess or try to summarize the literature I've found so far (the internet does not need more amateurs!) but if I find anything that seems solid I will update ya'll. In the meantime, if there are any exercise physiologists/scientists out there who can shine a light on all of this or point me in the right direction, please share!