Question - The Lactate Sample?
- What type of blood is preferred?
- By this we mean do you want to take whole blood or spin it down and take plasma. In theory plasma is better because the concentration of lactate in the plasma is much closer to the concentration in the muscles. But plasma has been very difficult to get so in the early 1980's laboratory instruments were able to more easily use whole blood than plasma and ever since the standard in journal articles and with testing athletes has been whole blood. But plasma is a more accurate estimate of the muscle lactate.
One time we were at a rowing conference and one of the sports scientists complained about the Accusport analyzer we were selling because it essentially measured plasma lactate and did not measure whole blood. Our competitor was telling potential customers that the analyzer was inferior to theirs because it did not measure whole blood. There was two things wrong with this. First, the plasma was the better measure and second the other portable analyzer also measured plasma and the competitor did not know this. Also the average coach and sports scientist did not know this so the competitor falsely disparaged the Accusport which was a very accurate instrument.
- Where do you measure lactate?
- This could be a very long answer. It would be ideal if you could measure lactate in the muscle but that is impossible for normal testing. What one is trying to measure is not lactate but anaerobic metabolism in glycolysis. The amount of lactate produced is a surrogate for this. Most of the pyruvate at low levels never turns into lactate but is used by the muscle as fuel for aerobic metabolism. The pyruvate not used turns into lactate and then it is mostly used by the current muscle but can drift out into the blood stream. As energy intensity picks up more lactate is produced and more appears in the blood stream. So it is blood lactate or the lactate that leaves the cell and ends up in the blood that one measures..
There are lots of places where you can measure the lactate in blood. If you have been to the doctor you are familiar with the technician taking blood from a vein in the arm. That is venous blood. It is possible to use venous blood but that requires a trained specialist. In the 1950's it was shown that lactate in arterial blood is a much better indicator of physical activity than venous blood. But only trained doctors should be attempting to get arterial blood so this is very impractical. It turns out that the blood in the ear lobe is close to arterial blood and the finger tips are also ok. That is why most top level exercise physiologists in Europe will use blood from the ear lobe but this takes someone with practice. On our CD-ROM there are instructions on how to take blood from the ear lobe. The easiest place to take blood is from the finger tip and this is the most common place..
In rowing one part of the body does not move during a rowing race. It is the foot and some researchers have used the big toe as the source of lactate during a rowing race. Before this, it was very difficult to measure lactate during an exercise piece. A national rowing coach told us a story about when he was a an athlete and he was being tested. There was a needle embedded in a vein in his arm and during each stroke a researcher would swing back and forth with the rower. This got boring for the researcher and he struck up a conversation with the rower. The conversation got so interesting that the researcher forgot what he was doing and the needle was ripped out of the arm of the rower. The researcher shouted to stop the piece but the athlete said "No way." It was one the best pieces he had ever done and he wasn't stopping just because his arm was bleeding.
Return to Questions Page
- Why is plasma preferred but whole blood ok for lactate?
- The reason plasma is preferred is as stated above because it is in close equilibrium with the muscles. Whole blood is composed of plasma and red blood cells (rbc's.) The red blood cells are negatively charged and because of this the lactate which is a negative anion is repelled as two negative charges repel each other just as in a magnet. The lactate levels in the rbc's is much lower than the plasma so the mixture of the plasma and the rbc's which forms whole blood is also lower than the plasma and the lactate levels in the muscles. Red blood cells make up on average about 40% of the volume of blood. Despite this, whole blood is the medium that most use in lactate testing. All portable lactate analyzers measure the plasma lactate but provide an estimate of the whole blood value as its basic reading. The Accusport or Accutrend Lactate and now the Accutrend Plus is the only analyzer that provides a true plasma reading. It has an option that estimates the whole blood lactate and this is what most people use.
This does not mean that the current portable blood lactate analyzers are not useful. They are extremely accurate and useful to the coach or athlete that is trying to understand what is happening with the body's response to training. They estimate whole blood lactates and they do this very accurately and whole blood lactate is highly correlated with the plasma lactate value.