This is a post that I had really meant to write several months ago, but never got around to it. Better late than never!
Back in April, I set out to have some metabolic testing done at a local tri shop. One of the things I was interested in discovering was my lactate threshold heart rate. Briefly (and not very scientifically), your lactate threshold is the point in exercise where your body produces more lactate than it can reabsorb. USAT says that well-trained athletes can generally operate just below this point for about an hour, but as soon as you go over the threshold the time drops to five or six minutes.
I’m a heart rate monitor junkie. I run with one almost 100% of the time. Of all of the random heart rate numbers that you can discover (maximum, resting, etc.), the lactate threshold heart rate is the most valuable to know (in my opinion). There are several ways of discovering your lactate threshold heart rate, the most accurate of which is a lab test. On the other end of the spectrum though are several running tests that you can perform to give you an estimate of your lactate threshold. I wanted to see how accurate these running tests were, so about a week before my test at the tri shop, I set out to perform my own field test. I wanted to do the field test first, since I knew that I could subconsciously skew my results if I knew my true lactate threshold first.
I opted for the Joel Friel 30 minute lactate threshold heart rate test, since it’s about as simple as it gets and it seemed to give accurate results to those who ran it properly. You simply warm up for a couple of miles, then run a 30 minute time trial (on your own, not part of a group or race). For the time trial, you just run as hard as you can for 30 minutes. It’s not easy, and it’s definitely painful if you’re doing it right. Your average heart rate during the last 20 minutes of the time trial is your lactate threshold heart rate. I created a workout in my Garmin, so that after the warm up it lapped after 10 minutes, and stopped after 20 minutes. That way the Garmin did all of the calculations for me of my average heart rate during that last 20 minute window.
My lactate threshold heart rate according to this field test was 189bpm (keep in mind that I have a higher-than-normal maximum heart rate, so my lactate threshold heart rate will be quite a bit higher than the average)
And then there was the lab test. I’ll spare you all of the details of that day (you can read about it here if you want), but the results of that treadmill test showed my lactate threshold heart rate to be………. 189bpm. Exactly the same!
I was definitely surprised that my results from both the field test and the lab test came out to be exactly the same. I guess this goes to show that (a) I pushed myself hard enough during the 30 minute time trial, and (b) Joel Friel knows his shit.
When I ran the half-marathon back in May, I paid more attention to my heart rate than I did my pace. I knew that if I went over 189bpm, I’d crash pretty quickly. There were a few points where I spiked over, but I was always able to bring my heart rate down below the threshold. For that race, my heart rate averaged 185bpm, just below my threshold heart rate. While I didn’t make my time goal, knowing that I was running so close to my threshold for so long helped me to realize that I ran the best possible race that I could that day – if I had pushed any harder I likely would have ended up walking to the finish line.
Anyway, since this post is a lot of words and no pictures, I’ll throw in the video from the treadmill test. They started me out at an easy pace, and then increased it every 60 seconds until I hit 6:00/mile pace. Then they added incline, 2% higher every 60 seconds. I crapped out running 6:00/miles at 10% incline.
How about you, do you run with a heart rate monitor?
Have you ever done a test to determine your lactate threshold heart rate?