During a recent rest week, I underwent a Lactate Threshold test.  I do these about 3-4 times a year to gauge where my fitness is at that moment and see how my body is handling and responding to training.  Like nearly everyone on the planet, I of course posted about it on Facebook.  This in turn led to a flurry of questions about (a) the results, (b) my VO2 Max, and (c) whether I had lost my mind.  I mean, who willing runs on a treadmill until complete muscular failure???  Apparently, I do.

One thing I did note, beyond my own potential lunacy (according to my “friends”), was the number of my friends who were unfamiliar with either one or both of VO2 Max and Lactate Threshold.  Given that I believe my friends are pretty smart people, I found that lack of knowledge a bit surprising.  What I have come to realize is that most people don’t know the difference between VO2 Max and Lactate Threshold and the value that they represent.

What does “VO2 Max” mean?

VO2 Max is defined as the maximum amount of oxygen that the body can deliver to working muscles per minute.  Given that all endurance activities are done in an aerobic state (they are endurance activities after all), your VO2 Max is pretty important.  Without the presence of oxygen, we all would be producing energy anaerobically, a terribly inefficient and short-lived way to work.  However, while VO2 Max matters, in my opinion, it matters far less than your Lactate Threshold and, a bit later, I will explain why.

What does “Lactate Threshold” Mean?

Lactate Threshold, or “LT”, is defined as the point at which your working muscles are producing more lactate than you can process, meaning more lactate is entering the blood than being removed from the blood.  Why does this matter?  Well, left unresolved, excess accumulation of lactate in the blood causes a pretty unpleasant sensation, namely the desire to vomit or fall down or fall down and vomit or pass out or vomit, fall down, and then pass out.  You get the picture.  Not good times at all.

How are VO2 Max and Lactate Threshold Measured?

There’s multiple ways to test for each, both field and lab.  But, the most common test is performed in a laboratory setting on a treadmill or a stationary bike.  The athlete runs or bikes, starting at a fairly easy, aerobic level of effort.  As the test progresses, the difficulty is increased and data samples (e.g., blood, exhaled air, heart rate, Rate of Perceived Exertion, etc.) are taken at regular intervals.  The test ends when the athlete can no longer perform, or as I like to call it, at Failure!  Umm, yeah, these tests can get rather uncomfy!

What does this all mean though?

These two markers, similar as they are, subtly provide different information.  I think people often confuse or misconstrue them because of ignorance about both the meaning but, more importantly, the value.  Your VO2 Max is really a predictor of athletic potential.  You can literally have never exercised a day in your life and have an olympic level VO2 Max.  In fact, if you have the money to purchase a VO2 Max machine, you can take it to the mall, test everyone, and find the next Lance Armstrong.  Well, maybe that’s not the greatest example but you get my drift.  Find someone with a killer VO2 Max, coach that person, and you too can be on the cover of “Awesome Coach Monthly” (oh, after you make that magazine).

On the other hand, unlike VO2 Max, which is largely set in stone the moment your Mommy’s and Daddy’s genes combined, Lactate Threshold gives you a great picture about your current level of fitness.  With proper training and other related factors (e.g., sleep, proper nutrition, recovery, etc.), your LT can change and hopefully for the better.  Looking at the two charts above, you see one of my earliest Run LT tests and my most recent.  My LT went from 6:39 min/mile to a 6:07 min/mile.  I can also tell you (as it is not shown on the chart) that I hit failure slower than 6:00 min/mile in the first test while I lasted until well under 6:00 in the second.  Trust me, those are big changes made through significant, consistent effort on my part over a few years of training. Likewise, in the charts below, if you look at my Bike LT data, you can see a very slight increase in HR at LT (2bpm) but a 20 watt improvement.  20 watts may not seem like much, but that is a big change.

As an endurance athlete, improving your LT can be a game-changer.  As your LT improves, you are generally able to work at a higher intensity for a longer period of time.  That’s the dream double-whammy!  Working harder for longer.  Note, I said “generally” though because other stressors will impact your day-to-day performances.

So, while VO2 Max will provide you with very accurate indicators of potential physical fitness, Lactate Threshold will instead provide you with an accurate picture of current fitness.  The knowledge gained from an accurately run and interpreted LT Test will allow a knowledgeable coach to create a useful, beneficial, and tailored training plan including accurate training zones.  This eliminates nearly all the guesswork of training and enables you, the future super-athlete, then nail your training.  That’s why, as a Coach, I focus on LT.  It enables me to give my clients accurate advice on how best to improve their fitness.  I know when I create their plans, including their training zones, I am doing so on information that is generally very reliable.

I hope this sheds some light on the differences between VO2 Max and Lactate Threshold and how best to use them.  If you have any questions, please leave them below.  I greatly appreciate commentary and feedback.  If you are not comfortable asking a personal question here, do not hesitate to send me an email; I’d be happy to help you.

Thanks for reading!