Sunday, April 7, 2013

Lactate Threshold testing

In a recent post, I talked about training zones and defined them in percentages of maximum heart rate. I also gave a very rough formula to calculate the maximum heart rate which was max HR = 220 – age. This formula is highly individual though, and it does not allow seeing the physiological progress one is making with his or her training. A better way to determine one’s training zones is to base it on a lactate test. These tests are available at prices around 100 Euros. About 5 months before my Ironman event last year, I did such a test. I chose to do it on the bike, but could have done the same on a treadmill instead, or both at some extra charge. It is usually sufficient for amateur triathletes to do the test on the bike and then estimate the run results pretty accurately by adding 5-10 bpm to the cycling maximum heart rate (MHR).
All in all, the test took 1 hour and you should have recovered for a couple of days from your last training before attempting to do the lactate test. After my tri bike was mounted on the bike trainer the test was started. I had to pedal with a cadence of above 80 rpm. I tried to stay at 85 rpm. The ergometer was set to a power of 100 watts which was increased by 20 watts every 3 minutes. My heart rate was being recorded continuously. At the end of each 3 minutes a droplet of blood was taken from the tip of my ear and the lactate content measured in mmol/l. After the 10th increase of 20 watts, I reached 280 watts and was unable to last for longer than half a minute or so. I had already given it all I had at 260 watts.
The recorded data was transferred into a graph (see graph) and an easy to read table with all relevant training zones. With exercise, the body produces lactic acid which is cleared out of the muscles at a certain rate. The higher the intensity is, the more lactic acid is produced and it starts to accumulate in the muscle as it cannot be cleared fast enough anymore. The point at which lactic acid production is significantly higher than its clearance is called Lactate Threshold (LT). Staying above that intensity for too long will make you feel your muscles burning and you will not be able to continue. One of the objectives of training is to move the LT point to higher intensities, i.e. higher power (watts) or speed.
The report also included a calculated VO2max number which was 43.3 ml/kg.
Now, I don’t know how good or bad my data was, considering my age and my level of training at the time, but what would be interesting to know is if I have improved at all since then. This information would tell me if my training is effective or if I need to change something.
Feel free to add a comment if you have done such a test and would like to share insights or ask questions.
KB = zone 1, GA1 = zone 2, GA2 = zone 3, EB = zone 4

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