Posted by Steve Magness
The Lactate curve: What is it and how to improve it:
LT is one of those buzz words that all sorts of coaches seem to be flocking towards. It’s the new VO2max. Everyone wants to have it measured and everyone wants to improve it. There are all kinds of literature out there on improving lactate threshold and what is the best way. Some of it can be extremely confusing and contradictory, so let’s first take a look at a couple of the problems with many of the accepted beliefs.
The most glaring mistake is a misunderstanding of what the lactate threshold is. In simple terms it is the point where lactate production equals lactate elimination, but what does that mean? What processes affect that? Most people are familiar with the idea of a lactate curve, but not many understand what that curve really means. Sorry to say this, but I really don’t either. In fact, no one truly understands the exact mechanisms behind it. However, there are some better approaches than the ones commonly used.
The first problem with LT is in figuring out where the heck this point occurs. Using a standard step test it is basically impossible to identify the true lactate threshold. What everyone is really doing is making a GUESS! The only true way to find a lactate threshold (or Max Lass: Max Lactate Steady State) is to run at a constant speed for around 20-30min. and take blood lactate samples and make sure there is very little increase in lactate from start to finish. Then, do this again at a faster pace. You have to keep doing this until you find the fastest pace that you can maintain without an increase in blood lactate. For training, it’s pretty much worthless and too time consuming. So we throw that idea out the window. So instead scientists have all sorts of ways to guess what the LT is based on a curve. Some ways are more accurate than others, but most involve a step test. For example a common test is to run 5x mile with 1-2min rest starting at an easy/moderate speed and increasing speed by 15sec per mile or so. For example running 5:35, 5:20, 5:05, 4:50, 4:35 for someone who has a threshold of around 4:55-5:00.
Since we’ve established that there is a problem with finding the lactate threshold, let’s look at the next problem with lactate threshold research. That would be the problem of knowing what the heck that nice little lactate curve means. Most people still assume that a shift to the right in the curve means a better LT, or better endurance, and a shift to the left means deteriorating endurance. The problem with that idea is it is too simplistic. There are two forces that mainly act upon the lactate curve. One is the aerobic capacity, think VO2max. The other is the less known one which is the anaerobic capacity, think of it as a measurement just like Vo2max but of the anaerobic system. In essence Anaerobic Capacity is Vo2max’s little brother. To give a quick refresher on how these work, the anaerobic capacity has the exact opposite effects on the curve as aerobic endurance (capacity) does. So an increase in Anaerobic Capacity would mean a shift to the left, and a decrease would mean a shift to the right. So it is this interaction between aerobic and anaerobic capacities that determines the way of the curve. How strong each are determine the curve. The stronger one of the capacities is, the more it pulls it to that side. So it is this pulling of each capacity that determines where the curve ends up. If the aerobic capacity is pulling more than the anaerobic capacity, then the curve will be more to the right. This is again still too simplistic and other factors contribute, but we will touch on these later.
So back to all that research. As I said, there have been tons of research on improving LT. Some of it is very good, but a problem arises in applying it to practical situations. Almost all of this research is based on the old model of only aerobic endurance influencing the curve. Why is this a problem? Well the exercises that some authors used to say improve LT may in fact shift the curve to the right because instead of truly improving aerobic endurance (and thus LT) they could have lowered the anaerobic capacity. For example, it just so happens that lots of running right at the LT tend to lower anaerobic capacity. So the author then thinks that a real increase of aerobic capacity occurred when one did not happen at all. So what we are left with is a false improvement of aerobic capabilities. This leads to false ideas of optimal training intensities.. So these scientist go tell everyone that training at threshold is the most effective way to improve the threshold. Which in essence it is, but in training for performance we are more interested in race times and not the threshold itself. Thus we are more interested in improving the mechanisms that are beyond the threshold, the aerobic endurance.
So the question then becomes, how the heck do we improve this LT and thus aerobic endurance? The answer is that it is much more complex than the old just do a tempo run solution. Most coaches/authors tell you to run at some pace that is at or slightly above or below this lactate threshold pace to improve it. Well this will shift the curve to the right, but is it for the right reason? The answer is sometimes it is and sometimes it isn’t. And in actuality a shift to the right because of lowered anaerobic capacity is not a bad thing depending on the event and anaerobic capacity level. For example in the marathon you want a lower anaerobic capacity because having too high of a level would mean you would consume too much glycogen and thus run out of fuel in the end of the marathon. This is one reason why a lot of athletes who try and make a quick switch from track training to the marathon are unsuccessful. They haven’t given themselves enough time to lower their anaerobic capacity (through a lot of mileage normally) so that they aren’t consuming lots of glycogen. In the marathon example it is okay to “artificially” improve your lactate threshold because that’s a good thing. In most track events however, when we talk about improving LT, we are really talking about improving the mechanisms that are behind the lactate threshold.