Saturday, April 26, 2014

What's Your VO2 Max?

If you’ve ever spent much time around endurance athletes then it’s highly likely you’ve heard the term VO2 max thrown around.  VO2 max is generally accepted as the best indicator of endurance capacity.  Technically, it is the maximal amount of oxygen one can use during intense exercise.  Having a high VO2 max is a prerequisite for reaching a high level of competition in endurance sports.  It “punches your ticket.”  

VO2 max and the amount that you can increase your VO2 max are largely genetic.  Training can increase VO2 max by 15-20% in a sedentary person, but the more highly trained you are, the less you will be able to increase your VO2 max (because you are already close to your genetic potential).  Improvements in VO2 max through training are due to increases in the size & number of muscle mitochondria, greater cardiac output per heartbeat, and increased capillarization to the muscles.  

I’ve always wanted to do a VO2 max to find out what mine is.  Part of it is curiosity and part of it is to improve the structure of my training.  By knowing your VO2 max, you can determine what heart rates you should be training at when given recovery, easy, cruise, tempo, and race-pace intervals in your workouts.  It prevents you from going too hard on your easy days and makes sure that you really nail your speed and pace workouts.  In addition, a VO2 max test will tell you your aerobic threshold and your anaerobic threshold.  Aerobic threshold is the heart rate below which you are burning fat for fuel.  As heart rate increases from aerobic threshold to anaerobic threshold you begin to rely on a greater percentage of carbohydrate for energy.  Anaerobic threshold is the point at which you are producing lactate at a higher rate than you can clear it from the blood and is presumably a rate-limiting factor in the ability to continue performing exercise.  Here's a short clip of my coach Tom Clifford of Without Limits talking about how a VO2 max test can help structure training (sorry, we had technical difficulties, so second is pretty poor quality)!

So last week I booked a VO2 max test at TOPS Athletics.  I was pretty excited about it but also nervous.  Given that it’s a maximal effort test, I knew I’d have to push myself to max exertion which inherently is not easy.  Additionally, even though I’ve been curious about it for a while, I wasn’t 100% sure I really wanted to know my number.  I knew I’d be disappointed if it was low.  Also, you have to fast for 4 hours prior to doing the test to minimize metabolic effects of digestion.  I like to eat very frequently throughout the day, so I knew going for 4 hours without food wouldn’t be pleasant.  I ate a large, carbohydrate-rich meal 4 hours before the test, but sure enough I was getting pretty hungry when it came time for action.  

The first step was to fit the mask.  The mask has a one-way valve that allows room air to flow through the top and into your lungs.  When you breathe out, gasses are collected through a long tube that connects to the computer which does all the analyzing.  Anyhow, it’s a lot easier to breathe without the mask.  It’s kind of heavy and does not feel natural.  But, it’s part of the test, so if you want to know your VO2 max you’d better wrap your head around the idea of producing a max effort while breathing into a tight-fitting mask wrapped around your head.  

The test starts out very easy; I think I started with a walk at 4.0 at 0% incline on the treadmill.  Every minute thereafter, the test administrator increases speed and/or incline.  So the first 5 minutes of the test are actually very easy.  I got up to 7.5 on the treadmill, which was the pace at which we planned to run the test, so after this we used incline to get me to my max.  From there, things got progressively more difficult.  I tried to keep good running form, remain calm, and focus on my breathing.  Jeff kept encouraging me to keep going.  In the final stages of the test I got up to a 12% grade at 7.5 mph.  The test ends when you can’t continue any longer.  It’s so hard not to quit when you get towards the end of the test!  Your chest is burning and so are your legs!  At the very end, I hit the stop button on the treadmill and jumped to the sides of the treadmill, took off the mask, and gasped for air while Jeff measured my 2 min heart rate recovery.  All in all, I think it only lasted about 12-13 minutes, but it was INTENSE!  Here's a quick look at what the test looks like in action:

My VO2 max was measured at 68.8 and I was happy with this.  I think I maybe could have pushed a little harder, but that’s always easier said in hindsight when breathing plentiful quantities of ambient oxygen!  Here is a table that compares VO2 max of non-athletes, cyclists, swimmers, and runners by age.  In general, women have a  10-25% lower VO2 max compared to men.  VO2 max appears to decrease with age, although this is thought to be due to decreases in training, such that if you continue to train intensely as you age, decrements in VO2 max will be attenuated.  Pretty interesting stuff!

VO2 Max for Non-Athletes & Selected Sports









Highly trained athletes can reach their genetically determined VO2 max within 8-18 months of heavy endurance training.  In fact, among trained endurance athletes, VO2 max is not the best predictor of performance.  This does not mean that after 8-18 months the athlete cannot get any faster.  At this point improving anaerobic threshold becomes the metric of interest.  I’ve been doing some research into how to improve anaerobic threshold, but that’s another blog for another day :)  

If you are interested in knowing what your VO2 max is, visit and click on the SynergyONE tab to find out more about the test and to make an appointment.  Trust me, it’s a lot of fun and you won’t regret doing it!

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