Lactate Threshold Heart Rate test

As explained in my last blog I have now entered the build phase of my ironman training and it is time to focus a little more on quality and intensity.

Good to my word, this week I have built in some higher intensity sets and the opportunity to review my heart rate training zones. The plan is to complete a 30min tempo test set for both the run and bike.

This morning I hit the 600m outdoor cycle track at Preston Park in Brighton for a 30min tempo run and to test my lactate threshold heart rate. Joe Friel, the well-renowned triathlon coach has this to say about the test:

Determine your lactate threshold heart rate (LTHR) with a short test. (Do not use 220 minus your age to find max heart rate as this is as likely to be wrong as right. This is explained in detail in Total Heart Rate Training.) This LTHR test is best done early in the Base and Build periods.

To find your LTHR do a 30-minute time trial all by yourself (no training partners and not in a race). Again, it should be done as if it was a race for the entire 30 minutes. But at 10 minutes into the test, click the lap button on your heart rate monitor. When done, look to see what your average heart rate was for the last 20 minutes. That number is an approximation of your LTHR.

Note: I am frequently asked if you should go hard for the first 10 minutes. The answer is: "Yes. Go hard for the entire 30 minutes." But be aware that most people doing this test go too hard the first few minutes and then gradually slow down for the remainder. That will give you inaccurate results. The more times you do this test the more accurate your LTHR is likely to become as you will learn to pace yourself better at the start.

Establish your training zones. Use the following guide to establish each zone by sport.

Run Zones

Zone 1 Less than 85% of LTHR

Zone 2 85% to 89% of LTHR

Zone 3 90% to 94% of LTHR

Zone 4 95% to 99% of LTHR

Zone 5a 100% to 102% of LTHR

Zone 5b 103% to 106% of LTHR

Zone 5c More than 106% of LTHR

Bike Zones

Zone 1 Less than 81% of LTHR

Zone 2 81% to 89% of LTHR

Zone 3 90% to 93% of LTHR

Zone 4 94% to 99% of LTHR

Zone 5a 100% to 102% of LTHR

Zone 5b 103% to 106% of LTHR

Zone 5c More than 106% of LTHR

So my average heart rate for the last 20mins of the test was 153bpm, which is my estimated LTHR used in the above formula to calculate my run zones.

The conditions were reasonable for the test - nice and dry and not too much wind. I do think I was wearing too much clothing and should have gone with running shorts rather than tights. I experienced a little bit of wind on the back straight but nothing too bad. I estimate my relative perceived effort (RPE) to be around 8 out of 10. Possibly I should have aimed to complete the test at 9/10.

Anyway, it has at least provided me with some decent base data. Over the coming months I am likely to repeat the test and make the necessary comparisons. My pace was 4:19mins per km, which I know I can improve upon.