Lactate Threshold

My Life as a Runner > training > Lactate Threshold
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I have been lucky so far in my marathon running where I have PRed in each of five races. Improvements were small in some races – less than one minute, while as much as seven minutes in other races. However, I have not see any speed gain in my 5K and 10K races this year, despite the speed training this spring. The purpose of the speed training and short-distance races are to improve my marathon time, so this spring training and summer races might show a nice uplift in marathon time. But the practical side of me think that I should see improvements in 5K and 10K race time since the speed training was geared towards these short distances.

In my marathon training so far, I have not relied on any scientific training method. I keep track of mileage and time, and I use my ‘race pace’ in my speed training such as track intervals and negative-split runs. But I have not incorporated lactate threshold (LT) or VO2Max in my training, simply because I’ve felt it was too much work to take necessary measurement, calculate the pace, and monitor the heart rate and pace during run. It’s one thing if you have someone else who can take all the measurement for you, but all this sounds very complicated and take fun out of actual joy running. It sounds like work, doesn’t it? But if this is going to help my race, after the failed speed training, I’d go scientific and give it a try.

Before I move on to my experiment result, here is my understanding of LT and the application of LT to training. Lactate is a by-product of anaerobic metabolism and produced during exercises or even day-to-day activities. The lactate production stays low in light exercise levels, and our body can process lactate faster than it is produced. As the exercise intensity increases, however, it reaches to the point where our body cannot process lactate fast enough than it is produced. This turning point is referred to as LT. After this point, the build up of hydrogen ions in our blood becomes high, which causes the muscles to become more acidic and then leads to performance degradation. A good news is we can increase our LT by certain exercises. In addition, we can use over-produced lactate as another source of energy. LT runs just do that. In LT runs, we would run at a LT pace, which trains our body to get better at dealing with high level of lactate and at consuming lactate as energy source. But you cannot run a marathon at LT pace. That’s where Tempo runs come in. While LT runs will raise our LT paces, Tempo runs build our endurance speed over a longer distance. Tempo pace should be 20 to 30 seconds slower than LT pace, and Tempo runs should be up to 10 miles for marathon training. A combination of LT runs and Tempo runs in marathon training should make a vast improvement in our marathon times.

North America Outgames Vancouver 10KOK, enough with the physiology and training stuff. What is my LT and LT pace? LT is often measured in the lab but it can also be estimated from 10K run (make sure you give your best shot to make sure you produce high level of lactate). Take the average heart rate of last 20 minutes of the race, and that should estimate your LT. Of course, LT pace is the pace from the same last 20 minutes of the race. So, I had strapped a heart rate monitor around my chest before Outgames 10K run started. The results are as follows:

Average heart rate: 165.8
Average pace: 6:21/mile

Now I can integrate this data into my training, and hopefully this will help improve my times!

* Photo courtesy of Stanley Ulmer

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