VO₂max is not a German rocket or a type of hair treatment: It is your maximum rate of oxygen consumption.  Even though it is actually a rate of oxygen use (often expressed in milliliters of oxygen consumed per kilogram of body weight per minute), it is popularly referred to as maximal aerobic capacity.

VO₂max has a bearing on your endurance-running performances, because oxygen acts as an electron catcher during energy producing metabolic processes which happen inside your cells.  Without a continuous supply of oxygen to catch the electrons, the energy production grinds to a halt.  Inside your muscle cells, the energy obtained as part of oxygen’s Yogi-Berra act is utilized to form ATP – a high-energy compound which is used to provide the direct energy for your muscle contractions.  To put it simply, if your muscles have a high rate of oxygen utilization they can create lots of ATP while you are running your 5K or marathon, and you can usually run faster than the poor sap with a lower rate of oxygen utilization.

VO₂max responds directly to training (unless, of course, you are an experienced runner who has already maxed-out his/her aerobic capacity).  A novice runner can expect a VO₂max upgrade of about 15 to 20 percent after 12 to 16 weeks of good endurance training, but the possible range of improvements is quite large.  Some runners might get only a small VO₂max nudge of 2 to 3 percent, while others could possibly raise VO₂max by 80 percent or more.

Each percent improvement in VO₂max generally improves performance to a similar extent.  For example, if you lift your VO₂max by 5 percent, you can expect a 3- to 6-percent enhancement of your 5-K time. 

However, that is only true as long as your VO₂max-expanding training did not hurt some other variable which influences your performance.  In one study, runners augmented VO₂max by 5 percent, but their 5-K performances did not improve at all because the training they carried out had hurt something called running economy, which is the actual oxygen cost of running at a certain speed.  In other words, these runners had a higher max rate of oxygen consumption, but it was “costing” them more oxygen than before to run at their usual 5-K paces, and thus their performance times did not improve.  As endurance runners, we ordinarily run our races at some specific, fixed percentage of VO2max.  If VO₂max goes up but your oxygen cost of running a 5K stays the same, you’ll increase your 5-K pace to keep that fixed percentage constant.  If your VO₂max and economy go up by similar amounts, the fixed percentage will not have changed, and your 5-K performances will stay the same.

“OK,” you’re saying, “I’d better get busy training in ways which optimize my VO₂max, but how do I do that?”

From an inside-your-body standpoint, you could hike VO₂max by boosting the size or strength of your heart, which would upgrade cardiac output (the amount of blood pumped by your heart per minute).  Since your blood carries oxygen, this would increase the rate of oxygen delivery to your leg muscles.  Provided the leg muscles could actually use that increased supply oxygen, your VO₂max would go up.

That’s a key point, because the leg muscles do have to get into the oxygen-utilization act.  They do so through a process called mitochondrial biogenesis, during which the density of tiny structures inside muscle cells - called mitochondria – increases.  The mitochondria are the stages upon which oxygen actually struts.  Increase mitochondrial density, and you’ve automatically got more places where oxygen can work to create additional ATP for your running.

When you carry out good-quality, VO₂max-expanding training, your genes inside your muscle fibers which code for mitochondrial biogenesis are unlocked and “read” during the recovery period which follows, and this triggers a series of metabolic processes which cause new mitochondria to be formed.  That’s a key adaptation to your training, one which you’ll want to maximize.

Another adaptation is the growth of new capillaries – tiny blood vessels – around your leg-muscle cells.  As your leg muscles become more and more entwined with these capillaries, more oxygen can be “dropped off” per minute of running (remember that blood is the oxygen supplier), and thus VO₂max can increase.

What kind of training should you carry out to make all these things happen?  In the old, dark days of endurance training, we believed that increased mileage was the key way to optimize VO₂max.  Studies showed that increasing weekly mileage from 10 to 20 miles might produce a 10-percent spike in VO₂max – and that burgeoning from 20 to 40 miles might cause another big uptick, maybe about 6 to 7 percent or so.

However, the research also uncovered the workings of a familiar physiological principle – the law of diminishing returns.  As mileage increased, VO₂max gains became more and more difficult to find.  In fact, above about 60 to 70 miles per week it was impossible to measure VO₂max gains at all.

You might be quite curious about this, since elite American runners often log 100 to 120 miles of running per week, purportedly to build “aerobic endurance.”  Why are they doing that?

That is actually a great question, since they are certainly not expanding VO₂max in the process.  A common answer is that they are building strength and stamina, but research suggests that such training actually may weaken muscle fibers, and any strength gained might simply be the strength necessary to continue running 100-plus weeks, not the strength needed to run a 5K or marathon faster.

Research has actually shown that intense training is the most-potent producer of VO₂max upgrades.  Here, “intense training” is defined as work which is carried out at speeds which cause oxygen-consumption rates to climb to 90 percent of max to VO₂max itself.

If you are a newcomer to the world of endurance running or consider yourself to be a slow runner, don’t be put off by the term “intense.”  Intensity is completely relative, depending entirely on your own ability as a runner: You don’t have to run a sub-five-minute mile to carry out intense training.  For many runners, for example, eight-minute per mile pace will be associated with 90 to 100 percent of VO₂max and will be great for pushing VO₂max upward.

But how can you figure where your individual VO₂max resides on the great VO₂max scale?  You could go to an exercise-fizz lab and have the darned thing measured for $175 or so.  But, it would be determined on a treadmill, and your oxygen consumption might be different out in the real world, on terra firma.  The protocol might involve treadmill inclinations to get your oxygen consumption up pretty high, and thus your result might not reflect your VO₂max on a level surface.  And – you would end up with a number, say 50 milliliters of oxygen consumed per kilogram of body weight per minute, for your VO₂max, and it would be hard to know exactly what to do with that number.

An easier and more-practical way to get a feeling for your VO₂max is to test yourself on a measured course, say a track, a measure roadway, or anywhere if you have a GPS device.  On a day, when you are feeling great, simply warm up and then run as far as you can in six minutes, holding a hard, steady pace.  Measure how far you have run, and then cool down with a couple of miles of light jogging.

You can then calculate a training pace which should be intense enough to push your VO2max upward.  For example, if you covered 1600 meters during your six-minute test, that’s an average speed of 1600/meters divided by 360 seconds (six minutes), or 4.44 meters per second.  As you are training, it’s hard to know whether you are actually hitting 4.44 meters per second or not, so it is best to convert this to a per 400-meter tempo.  400 meters divided by 4.44 meters per second yields 90 seconds per 400 meters.  That’s nice!  If you set up a workout which focuses on running 400s in 90 seconds each (with about the same amount of recovery time – 90 seconds – between the 400-meter work intervals), you would be assured that you were running fast enough to evoke any VO2max response which is physiologically possible for you.

If you cover 2000 meters during your six-minute test, the average speed would be 2000/360 = 5.56 meters per second, for a training tempo of 400/5.56 = 72 seconds per 400 meters (with 72-second jog recoveries).

If you complete 1200 meters during the six-minute affair, average velocity is 1200/360 = 3.33 meters per second, and desired training pace is 400/3.33 = 120 seconds per 400 meters (with 120-second recoveries).

You can see that the process of creating a VO₂max-expanding workout is really simple.  If you use this kind of training session approximately every week or at least every other week, you’ll be well on your way to augmenting your VO₂max.  Be sure to re-check yourself with the six-minute test every six weeks or so.  Your six-minute performance should gradually increase over time (it doesn’t have to increase every time, though), and as it does it will upgrade your training paces in a natural, organic, and productive way for you.

Finally, it’s nice to know that running a 5-K race is one of the very best ways to stimulate VO₂max improvement.  Most runners achieve an intensity of about 95 percent of VO₂max or so during their 5-K competitions, and that’s right in the desired zone for making the heart, mitochondria, and capillaries get into VO₂max-building mode.

Questions about this article?  Someone is always minding the store at www.educatedrunner.com  Contact Owen at owenanderson2006@comcast.net for a personal response.