Lactate Testing

trimike

Before I tested myself last week I went to a lab for a bike test. They checked my blood when I arrived and told me that my lactate level was too high to test - 3.5 mmol. The tech thought I was likely chronically dehydrated. I've rescheduled for this Friday but I don't want to waste the time or $ if my self test is good enough. Any experience with this?

Tom Glynn

The problem with blood tests is that you have to keep getting them and they are expensive and usually inconvenient. And even if you do get one, what do you do with the information? You're not really going to know you're doing better until the next needle.

That's why I like the tests we do here, either with a power meter or HR. They are free, repeatable whenever you want and allow you to benchmark yourself in less than an hour. You can test monthly, reset zones, work hard for a while and retest.

Simple and easy.

mattsull

My perspective is that I really don't care what's happening with my blood or cells on a practical level. I'm a power athlete so my main focus for my bike test is watts.I often don't even wear a HR strap. I want to know how many watts I can push in 42 minutes that will give me workable, challenging zones for my future workouts.The system we use is reliable for that. Just as reliable for a HR athlete.

Regarding the tech telling you that your lactate levels were critically high, I would post to the Medical Forum.

Coach Patrick

Having done some testing back in the day as a coach (not blood lactate though), I can tell you the equipment is highly variable. Same data in hands of 8 folks can lead to 8 different interpretations for you. Better to save the money from the 6-8 tests/year required to monitor performance and put to a PM!!!

tgarson

Dr Skiba was commenting on the subject of the importance of blood lactate testing / measurement over on ST today, I'll grab the good part:

Hello Vern et al...

I think the problem here is that we have a whole lot of terminology that people in sport use somewhat recklessly and inaccurately. Let me try to help clear things up a little bit. (Besides all the athletes I coach / sports medicine I do, I work in one of the best laboratories in the world with respect to this stuff). In short, there are really two "thresholds", if you like.

At the low end, we have Lactate Threshold or LT. This is simply the point where lactate rises by 1 mmol / L over exercise baseline. In other words, if you are zipping along at 1.5 mmol / L, and you speed up enough that you reach 2.5 mmol / L, you have crossed LT. This is actually a lot easier to do than most athletes realize. You could ride around at / about LT for a couple hours without much of a problem.

In the middle, we find OBLA, or Onset of Blood Lactate Accumulation, is when you hit 4 mmol / L, irrespective of where your baseline was. This term is not used frequently used anymore, and we should probably avoid it.

At the high end, there is the MLSS, or Maximal Lactate Steady State. This is simply the highest level of exercise we can maintain while maintaining a steady concentration of lactate in the blood. Any higher, and we see a progressive increase even if we maintain a constant power. MLSS is intimately related to the concept of Critical Power, and is probably one of the biochemical manifestations of reaching Critical Power (if you are on a bike) / Critical Speed (if you are running or swimming or whatever). The physiological "stuff" going on at this point is probably what results in the "feeling" of "threshold", and is what is partially responsible for what Andy Coggan calls "FTP". FTP is probably not reflective of some unique, alternative threshold phenomenon. It is just convenient shorthand, and results from your body "understanding" that if it goes much harder, bad stuff is going to happen (like inexorable fatigue). In other words, FTP that you observe in the field by doing something like a 40KTT is probably pretty close to, but just slightly lower than CP in a well trained athlete.

This begs the question, what is CP and how do you measure it? If you did a bunch of all-out exercise tests...i.e. went as hard as you could for 3 minutes, and then for 5 minutes, and then for 10 minutes, and you graphed them on a piece of paper, you'd get a curve. It would be high on the left, and then slope down to the right. The place where it seems to level off is CP. You can also make the same graph by using joules (this is easy... watts = joules per second), and you get a straight line, and the slope of that line (rise / run) is equal to CP. (PLEASE NOTE: This is Critical Power, the real scientific one, not the bastardization used by many people to refer to the hardest they can go for some period, like "CP30" for "the hardest I can go for 30 minutes).

Basically, it goes like this. As you cross LT, you begin recruiting less efficient muscle fibers, which tend to use more glycogen / carbohydrate and less fat for fuel. The result of this is an increase in lactate in the blood. This is not a problem. The lactate is taken up by other cells / organs and is metabolized. (Lactate is an energy-rich compound, not a waste product. It doesn't in and of itself cause fatigue). In triathlon, it is a problem only in the sense that your body glycogen / carbohydrate stores are limited, and that you can "bonk" if you aren't getting enough carbs in while you race (if the race is long enough). Additionally, we see the emergence of what is called the "slow component" of oxygen use. In other words, let's say your LT is 170W (not unreasonable for an age-grouper). Below 170W, you are using some constant amount of oxygen. If you made a graph, you'd see your oxygen use rise up as you started, and then become a straight line. Now, if you ride 180W, what you will see is that your oxygen use seems to kind of level off, and then (maybe a minute or two later) there is another "hump". In other words, it appears as though your body suddenly realizes it needs more oxygen to do the job. However, this second "hump" also levels off, so you again end up with a steady state of oxygen use. It is just that you are using more than you might otherwise have expected.

The key is that so long as you stay below Critical Power, your body is able to maintain a physiological steady state. After several minutes, oxygen use levels off, lactate concentration levels off. In the muscles, the concentration of creatine phosphate (PCr), ATP, inorganic phosphate and hydrogen ion (i.e. pH) stabilizes. Once you go hard enough to cross Critical Power, bad stuff happens. In other words, let's say your CP is 240W. If you go to 250W and hold it, things get interesting. Even though the work rate is not changing, there is still a progressive increase in the amount of oxygen used, a progressive increase in lactate concentration in the blood, and a progressive decrease in ATP, PCr and pH inside the muscle. It is very cool, because you cat actually watch a lot of this stuff happen with a specialized MRI setup. Eventually, you reach some limiting level of the concentrations of the other stuff, fatigue, and must stop, or at the very least drop to some much easier intensity.

I encourage people to stop thinking in terms of lactate. Everyone does it, because it is so easy to measure. However, it is really just a very indirect market of some much more important / interesting stuff that is going on in the body, most of which is not easy to measure without expensive gear. From the perspective of the average (or even professional) athlete, it is simply important to realize that you don't want to be crossing CP with any significant frequency or for any significant duration if you are expecting to do your best in a triathlon, particularly a long course triathlon.

Hope that was helpful.

Phil
--
Dr. Philip Skiba

William Jenks

You can't dilute yourself down to 1 mM lactate if you're at 3.5 mM. Tripling your water volume would be a challenge! :-)

That said, steady state concentration is really a function of both production and removal reactions, so it doesn't have to be just water volume. I'm not an expert on this, but 3.5 mM at rest does sound outrageously high. Could easily be the thing that Patrick says, though: amateur analytical chemistry. (i.e., user error or instrument maladjustment)


William
(a professional chemist)