Thursday, November 29, 2007

Threshold Run Testing

So a couple of months ago, when I got this crazy bug to do a marathon, I decided to do a running lactate threshold test. Last year I did one in the lab for the bike. In the lab it is a simple measure of blood samples taken when producing a progressively harder and harder power load. What did I learn? Mostly that I have a little strength but I am incredibly slow because of a poor power to weight ratio, but then again I already knew that. I am reminded of just how weak and slow I am on my weekly ride up Mt. Wilson. So what is the point?

The point is to train with the proper intensity so that I can make the maximum possible gains. I don't just want to finish the LA Marathon - I want to do it faster than I ever thought possible. A four hour marathon is probably unreasonable, but maybe four and a half hours is doable with the right training. Slow for some people but incredibly fast for me.

The goal of threshold testing is to find that level of effort (which is sport specific) at which your body no longer can supply its energy needs from the burning of fuel with oxygen (i.e. aerobically). Once you go above this level, the body can still supply additional energy but it will be without the use of oxygen (anaerobically) and will result in the acidic waste product lactate which is associated with fatigue. So theoretically the threshold is the maximum level of intensity that can be sustained over an extended period of time because only a small amount of lactate is produced.

Once equipped with your threshold you can tailor your training regimen to maximise the returns. There are three basic intensities at which to train, each of which have their own benefit. Sub-threshold training is at an easy pace, well below the threshold. This intensity level develops basic endurance and stimulates increased vascularization (i.e. more blood vessels and capillaries). Because the point of these workouts is endurance they are usually the longest you will do and also sometimes called Base miles or LSD for long slow distance.

The second level is Threshold training in which you train at or slightly above your threshold. This training is aimed at raising your threshold level, thus increasing the work that your body can perform on a sustained basis. The body responds to these workouts with increased efficiency in oxygen uptake, usually through an increase in the number of cellular mitochondria, as well as developing an increased ability to utilize or buffer lactate. So even when lactate is being produced at a high level it is also quickly being removed, avoiding the buildup of lactate and its associated fatigue. Tempo runs are a classic threshold workout, but there are others such as tempo intervals, cruise intervals, etc.

The last level is Supra Threshold training, also known as speed work or interval training. This training involves relatively short and intense efforts that greatly exceed the threshold level. because they exceed the threshold level they become anaerobic, but they still have benefits for aerobic performance. First by running faster you can learn the proper form and develop the proper neurological firing of the muscles. What is really being developed is efficiency. As these skills improve they will also improve the efficiency of slower running.

So there you have it. The three basic training levels. Here is a great resource by Greg McMillan listing the major types of runs that you can do which fit into each intensity level.

So finding your threshold level is good, but I didn't want to pay $200 to have it determined in the lab. If you have that kind of money to spend on these tests that is all well and good, but I would rather save the money for a time trial bike, thank you very much, and in any case you probably want to test yourself every month or so to measure your progress and keep your training plan up to date. So I did the threshold test advocated by Mike Ricci of D3 Multisport. Joe Friel also has a similar test in his book, The Triathlete's Training Bible (2nd Edition).

To do the test you need a heart rate monitor (but absent a heart rate monitor I suppose you could also just use your your pace if you had an easy way to measure it such as on a track and on the bike you can certainly use a power meter). I preprogramed my HRM with the various stages of the test, but you don't need to do this as the test is very simple. I started with a 15 minute warm up. After the warm up you do a 30 minute time trial. The idea is to go as fast as you can for thirty minutes such that at the end you feel that you could not have gone any faster, but not so fast that you have to slow down during the time trial. The pacing is a little tricky for a novice and the first time I did the test I had to slow down quite a bit right around half way through the time trial, which probably screwed up the test. The second time I did it, I was ok. So there is a little learning curve, but it's not too bad. During the time trial you want to press the lap button after ten minutes and then again at the end of the thirty minutes. This way the heart rate monitor will give you the average heart rate for the last 20 minutes of the time trial. This average is your threshold, and is exercise specific. That is, you need to test running and cycling separately. I recommend a cool down after the time trial, but for the purposes of the test this is optional.

I did the test yesterday and got the average of 161 beats per minute at a 9:58 pace. It was slower than I had hoped, but man was it an improvement over my last test. It was a whole 4 beats per minute greater after only 8 weeks of training, and my pace was about 32 seconds per mile faster. I can definitely live with that.

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