Lactate Threshold Explained…
Warning. This post is a bit heavy going so read when your mind is fresh. 
If you’re just starting out on the beginner or century programs, feel free to skip this unless you’re interested.
Lactate Threshold (LT) is going to be a very important concept for you to understand. Parts of the program require strict discipline with LT. Exceeding LT is the point where your body is creating more lactic acid than you can metabolize.
At your lactate threshold you can sustain the same effort indefinitely, (provided you have enough carbs and water etc) as your body can metabolize lactic acid faster than it is being produced. If you are five beats per minute over LT, you will gradually be unable to sustain the same effort and speed and performance will drop while pain and suffering will increase.
There are many ways to measure your LT. Blood lactate measurements are conducted by removing blood from your system during peaks in output (such as exercise) and compared to your heart rates.
Testing done with lactate measuring tools is very difficult.
It requires sterilised environments, set on stationary bikes, in controlled circumstances. These tests can be done for a large sum of money at many sports science institutes, but effective results can be obtained using calculations, formulas and self monitoring over time. This program is ideal for self monitoring as LT can be gauged during the first four to five weeks of this program.
LT calculation requires knowledge of your maximum heart rate. Maximum heart rate is simply the maximum heart rate achieved before exhaustion. This measurement can be obtained three ways.
First way, 220 minus your age. This is an old method but is usually close to the mark.
The second way, this is a more accurate way of measuring and has been proven to be slightly more accurate, 205.8 − (0.685 x age) .
The third way and by far the most accurate is to put yourself through a cardiac stress test. This is typically conducted in the presence of medical professionals and the intensity of the exercise is periodically increased while the heart is monitored via an electro cardiogram. This is obviously the safest and most accurate way to measure your maximum heart rate, but also the most expensive.
LT is considered to be 85-90% of maximum heart rate. This is a very close calculation based on hundreds and thousands of athletes. You can get it closer with the blood lactate test, but many factors also mean this is not always accurate.
I have been through years of this type of testing and the amount of variables that effect blood lactate would lean me towards giving the advice that it’s not worth the money.
Testing needs to occur at the peak of the effort. Blood needs to be taken right when the athlete is hurting the most. The taking of blood (usually from the ear) often takes so long to extract that the blood lactate levels have dropped.
The need to utilize a controlled environment with sterile facilities is also very difficult to control.
Any how, with the formula above it is very close and if you listen to your body I believe you can achieve a more accurate LT point based through your heart rate monitor. For example Maximum heart rate = 190 BPM, LT = 190 x .85 =161.5 BPM. 190 x .9 = 171 BPM. Lactate threshold is between 161 and 171 BPM.
