Blood Lactate Myth
BY- Sean Burke
The last several weeks I’ve been attacking sacred cows, but this week we’ll move on to myths. Today, we are going to dispel the myth that blood lactate is a bad thing, a waste product, or a by-product.. In fact, lactate is required for life, and is actually in your blood all the time.
Blood lactate gets a bad reputation. It is known as the harbinger of pain, discomfort, and and race ending breakdowns. While it may be all of those things, it is also a metabolite that is always present in your blood, and is necessary for high intensity exercise. Without lactate, you would be unable to bridge up to that break 20 seconds up the road, or lay the smack down going up that hill. Even worse, all your red blood cells would die.
Lactate is a metabolite produced as part of the first phase of carbohydrate metabolism, and carbohydrate metabolism is required for high intensity exercise. This first phase releases some the molecule’s energy to use in your working muscles, but not all of it. Now, you are going to have to remember some of your high school biology. Remember the mitochondria, the powerhouse of the cell? For starters, your red blood cells don’t have mitochondria, so they make lactate all the time. If they didn’t make lactate, they wouldn’t be able to make the energy they need for metabolic processes. This means that you have lactate in your blood all the time, as the red blood cells make it and just release it out into the rest of the blood. At rest, or low to moderate exercise intensities, your working muscles are also making lactate, but it is being used as fast as it is being made. The lactate simply enters the mitochondria of other cells ( in slow twitch muscles and other places) where the lactate molecule is metabolized and the rest of the energy is liberated. When exercise intensities get higher, the mitochondria in the working muscles are not able to keep up with the lactate being produced in the muscles. The lactate builds up in the cells of these muscles and causes the discomfort you know so well, along with decreased strength of muscle contractions*. This buildup of lactate in the muscle causes the lactate to spill over into the blood as well. The lactate is then used and the energy is liberated in non-pedaling muscles like your arms and torso and your heart, while much of it is metabolized in your liver. But when you are riding hard, the lactate simply can’t be removed and metabolized as quickly as it is entering the bloodstream, and blood lactate levels begin to climb This buildup in the blood is what is commonly referred to as lactate threshold. If you stop pedaling so darn hard, the lactate levels in your legs muscles will go down and some of the lactate will also go back into the leg muscles to be utilized there. Once you slow down enough or stop exercising completely, the lactate levels will go down to baseline. It could take anywhere from a few minutes to almost an hour, depending on how high your blood lactate levels were. So the fact is that lactate is part of normal metabolic processes and you always have some in your blood. You need the stuff for your red blood cells to do their thing, and for your muscles to be able to produce high work outputs. Without the ability to make lactate you’d never be able to go truly hard (how most races are won)
Bonus Myth: High blood lactate causes muscle soreness
Fact: High blood lactate and/or accompanying metabolites cause short term discomfort, but does not make you sore the next day. Delayed Onset Muscle Soreness. (DOMS) is caused mostly by actual physical micro-tears in the muscles. Some of this can happen during hard rides, but it tend to be far worse in runners and weightlifters due to the eccentric ( Muscle lengthening under load) inherent in those sports.
* Actually it is not the lactate, but more likely the disassociated hydrogen ions that cause these consequences, but I am trying to keep this simple J