 What
is lactate threshold?
Blood lactate gets a bad reputation. It is known as the
harbinger of pain, discomfort, and soreness. 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. With out 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 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? Well, at
low/moderate exercise intensities this lactate enters the mitochondria and the
rest of the energy is liberated from the molecule. When exercise intensities get higher, the mitochondria in the
working muscles are not able to keep up with the lactate being produced in that
muscle. 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 where the concentrations are lower.
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 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 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.
* Actually it is not the lactate, but the disassociated hydrogen
ions that cause these consequences, but I am trying to keep this simple.
Read:
Myths about lactate/lactic acid
Why you always
have some lactate in your blood
or
for those of you that want to get a bit more geeky about the subject.....
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