If you’ve been around the sport of triathlon long enough, you’ve probably heard something similar to this: “Sorry dude, I can’t go with you up Lookout Mountain, I’m only supposed to be in Zone 2 today.”, or “Man, those 4x 4-min intervals at Zone 5 were a killer!!” If you’re a beginner though, you probably think that there is a secret language that you don’t know yet. What these athletes are talking about are training intensity zones, and the most common method that coaches use to define these zones is the Lactate Threshold test.
The lactate threshold test is performed in a variety of ways, with the most common being a step-test (i.e. increasing pace or resistance on a specific timed interval). It’s done on either on a treadmill or on the bike with a trainer while taking periodic blood samples that measure absolute value of lactic acid in the blood (measured in mmol/mL for all you Chemistry geeks!). The Lactate Threshold Heart Rate is defined then, as the place where either the value of lactic acid crosses 4 mmol/mL or there is a significant jump in value of greater than 1.5 mmol/mL. (There is some subjectivity as to where the specific LTHR is and can even be different for different types of athletes. But what is more important is that the testing protocol observed during baseline testing is maintained on subsequent assessments – only then is the LT test valuable). Once the coach is armed with the LTHR, pacing/power zones can be created based on that value. The zones typically differ for different sports – for the run, I use the following adapted from Joel Friel: Zone 2 is 85-90% LTHR; Zone 3 is 90-95%; Zone 4 is 95-100%; and Zone 5 is greater than 100%. For the bike, I use Andrew Coggan Zone Calculation: Zone 2 is 68-83% LTHR; Zone 3 is 84-94% LTHR; Zone 4 is 95-105%; and finally Zone 5 is greater than 105%. Again, this is subjective by each individual coach, but the importance is consistency.
The lactate threshold test also gives coaches quite a bit more information than just the LTHR. It becomes the baseline by which to measure improvement throughout the course of training. For example, if an athlete runs a pace of 7:00min/mi at a lactate value of 4 mmol/mL and when we test her again in 6-months, she runs that same pace with a lactate value of 3.5 mmol/mL, then we have made a significant improvement.
Below you will find the results of an LT test that I performed on an athlete earlier this year on the bike:
As you can see in the graph above, the lactate threshold curve crosses the 4 mmol/mL value at approximately 190W with a corresponding Heart Rate of approximately 153 beats per minute (There is also a significant deflection of 1.4 mmol/mL at that same point). We defined this as his LTHR. His zones, then are as follows:
Zone 1: Less than 104bpm
Zone 2: 105 – 128
Zone 3: 129 – 143
Zone 4: 144 – 161
Zone 5: Greater than 161
This test was done in September on an athlete who is currently looking to improve his major limiter which was the bike. Over the last two months, he has been strongly focusing on the bike and when we test again at the end of December, we hope to see this entire curve shift to the right.
The importance of a Lactate Threshold test cannot be understated. In addition to a baseline measurement, having these training Zones can gives coaches and athletes insight into how your body is physically adapting to training stresses. Correlating these numbers with Rate of Perceived Exertion (RPE) can give coaches and athletes leading information into whether the athlete is getting ill or worse, approaching the precipitous cliff of overtraining.
I strongly encourage all of my athletes to get a lactate threshold test done. In fact, starting this Friday and running through the end of December, for any new athlete, I am offering a Free LT test ($150 value) with a 3-month coaching commitment, or a Free LT Test ($150 value) and the first month free ($200 value) to any with a 6-month minimum coaching commitment.
Head Coach, TriCoach Colorado