Blood Lactate Testing Myths
Hi this is Dr. John Martinez, Medical Director of Coastal Sports and Wellness Medical Center in San Diego, California.
Today, we’ll be talking about some myths and facts about both lactate testing as it applies to our endurance training—we’re talking about:
- The lactic acid myth
- The muscle burn myth and lactic acid
- The muscle pain myth
- The lactic threshold myth
Now the first myth is about “lactic acid” and that lactic acid actually appears during exercise, so it’s really the true things, it’s more of a misnomer and that lactate is actually the proper term and it’s actually a by-product of glucose utilization and a lot of coaches and athletes are taught or told that lactic acid is something that’s actually bad, when in fact that if we look at the whole breakdown of exercise metabolism, it’s that as glucose breaks down, it’s broken down to a by-product called pyruvate and eventually into a pathway that produces lactate.
There may be some true lactic acid that’s formed very briefly, but then the lactate is actually a salt by-product that’s produced and importantly, for athletes and coaches to understand is that lactate is actually used by the body specifically, the brain and the heart for fuel and this falls into a concept termed the lactate shuttle as first proposed by Dr. George Brooks up in University of California, Berkley who’s done a lot of research on this concept.
The next myth that we’re going to talk about is that muscle burn myth and this is something that I think most athletes have been told, if you’ve ever been in a spin class, ever gone out to the track and done track workout or a speed workout and told that that burn is that that lactic acid building up and again, if you go back to that first myth that we’d already talked about, the true term we should be using is lactate, but it’s actually also false that lactic acid build up causes that muscle burn that athletes experience at the high intensity exercise.
The fact is that that muscle burn is actually more of an acidosis that occurs when hydrogen ion build up and probably some other by-products in the intense exercise. Lactate itself doesn’t seem to cause that muscle burn and if you look at the research studies, we have athletes that have much different levels of blood lactate levels that have different experiences or different complaints as far as how much muscle burn and muscle discomfort there is.
So again, that lactic acid or that lactate build up doesn’t cause that muscle burn.
The third myth we’ll be talking about is muscle pain myth and that lactate or lactic acid build up causes the muscle pain most athletes experience 24 to 48 hours after a hard workout. Well, the truth is that, lactate is actually cleared from the muscles usually within an hour of most exercise, even the more high intensity exercises, and we know this because when we do a lactate testing on our athletes, we plot out the increase in the lactate levels as we increase the exercise intensity and then as we have a recovery period after exercise, we actually do a recovery lactate test to watch how quickly the athlete’s body is able to metabolize that excess lactate.
So the truth is that, a lot of that muscle damage and muscle pain that occurs 24 to 48 hours actually probably do more to micro tearing of muscle and usually, we see more muscle pain and more micro tears when there is more eccentric muscle contraction and this should be something, as far as downhill running and the eccentric lengthening of the quadriceps muscle and if you’re in the gym during a bicep curl, this would be the negative that a lot of body builders do when they slowly extend out the bicep under a heavy weight and you get more micro tearing and therefore, more inflammation and damage to the muscle and that’s what we think that delayed onset muscle soreness is that occurs, a couple of days after a hard workout.
The final myth we’ll talk about is the lactic threshold myth and that myth is that there’s a defined point where the body switches from an aerobic to anaerobic metabolism called the lactate threshold. Well, the truth is that there’s really no defined switch from aerobic to anaerobic metabolism. There’s actually more of a mixture of aerobic and anaerobic metabolism in most exercise intensities and if you think about this at a lower intensity, you do use mostly fat as your main source of energy.
But there’s always just a little bit of glucose metabolism that’s occurring and as you slowly increase your exercise intensity, there’s more of a slow transformation or slow transition to a more heavily anaerobic metabolism, but there’s no true flip of the switch where you go completely aerobic to completely anaerobic, it’s more of a transition zone that we hit.
One of the other things that we try to measure with our athletes is what we call the maximum lactate steady state, which is that steady state exercise level for either running or cycling where the athlete can maintain a constant lactate production and lactate metabolism and that’s probably the level that most athletes can race a long distance, race out over an hour.
Interested in finding out out more about blood lactate testing?
We offer blood lactate testing in San Diego at our sports medicine center and sports medical director.
Give us a call at 858-678-0300