15 May 2012 ~ Comments Off on Lactate or Anaerobic Threshold

Lactate or Anaerobic Threshold

Recently I posted a question on a cycling forum. It was “how high should one’s heart rate be on a long extended climb?” Then general consensus was “try to keep it below your lactate threshold” or “don’t go into the red.” (Lactate threshold is also called anaerobic threshold or maximal steady heart rate.) I know what my maximum heart rate is, but my LT is subject to discussion. In the many fitness books which I have read, there are several methods for determining this. But none make as much sense, and are as easy to calculate as this technique by John Hughes (author of the book Distance Cycling), who posted the following comment (used with permission):

Lactate threshold is the level of exertion at which you start to accumulate significant amounts of lactate in your blood.You can get tested in a physiology lab—they put you on a trainer, increase the wattage every 3 minutes and take blood sample every 3 minutes. The equipment plots HR vs lactate concentration and at some lever there is an inflection point where lactate concentration starts to increase more rapidly.

There are several field protocols for estimating LT.  I have clients warm up thoroughly and do a 30-minute TT [time trial]. I’m on the road, but if I remember correctly Friel* suggests a 30-minute TT and the average HR for the last 20 minutes is close to LT.  Two keys:

1.  warm up thoroughly including about 5 minutes at close to what you think is your LT and recover for about 5 minutes

2.  try to ride the TT at very close to the same intensity throughout

If you do this in competition average HR for the 30 minutes will be about 103% of LT.

LT ranges from 70-90% of max HR depending on fitness.  I usually have clients do the test early spring and then repeat every 4-6 weeks using the same course. This way we can check fitness—increased speed and perhaps change in HR.

You can train to improve your LT by doing either intervals or more random speed work. Longer efforts below LT + recovery are more effective than shorter efforts above LT. Speed work above LT takes more recovery time before the next quality workout so you get less total quality volume in a week.  How much?  Start with 30 minutes of mixed intensity, broken into X hard efforts totaling about 15 minutes and Y easy efforts also totaling about 15 minutes.  Build to 45 minutes of mixed intensity (or 60 minutes if you like pain!)

LT varies by sport because of the different muscles involved so if you really want to train using HR zones based on LT, then you need to do separate tests for different sports. Running is weight-bearing, cycling and swimming aren’t. Swimming and XC skiing use the arms.  Etc.

When I say don’t go into the red when climbing (or ever unless in a road race), I mean stay below LT. If you are fit you might be able to attack a climb at 95% of LT and hold that to the top. Or you might start @ 95% of LT and back off slowly as you climb. Or start a little lower and push a little harder toward the top.

LT isn’t really a “point” where all of a sudden you go anaerobic, but it’s a region where you start accumulating more lactate with increasing metabolic costs in terms of fuel efficiency as I said in the earlier post. So it’s better to climb steadily at 95% of LT instead of starting up at 90% of LT and ramping up to 100%.

I’ve written an eArticle on Intensity training which is for sale for $4.99 at RoadBikeRider.com:

http://www.roadbikerider.com/e-articles/intensity

Huffa, puffa!

John

www.coach-hughes.com

* Joe Friel, author of the Cyclist‘s Training Bible. Per Joe’s blog, he says:

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. (If you really are using a race then it needs to be about 60 minutes duration. The reason for ths is that you go harder when in a real race – about as hard as you would go for 30 minutes alone.)  At 10 minutes into the 30-minute test click the lap button on your heart rate monitor (in a 60-minute race don’t worry about this). 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.

As it turns out, my maximum heart rate on a bike (this year at the age of 58) is 161 or 162. When backcountry skiing, I get a slightly higher amount. Using the above formula, my LT is about 138, which is 85% of my maximum. According to Edmund R. Burke, PhD, “Most elite cyclists reach their lactate threshold at 85 to 90 percent of VO2 max, whereas untrained individuals reach theirs at 50 to 70 percent of VO2 max.” (p. 29 or the 2nd Edition of Serious Cycling)

Also, check out this page on my blog about how to measure your maximum heart rate.

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