Thursday, September 25, 2014

Lactate Threshold Testing

For some time, I’ve been interested in testing my Lactate Threshold (LT) but have generally shied away due to cost and inconvenience. While it is true that CU Sports Medicine has a facility in Lone Tree, they also get a hefty fee for testing. I’m sure it is of high quality but it’s also probably way more than I need.  It’s kind of like buying a big four bedroom house. It might come with some nice amenities but for me, most of what I bought would go unused.

All of that changed with my coach’s recent announcement of an off-season training program designed to help improve one’s weakest event. Included in this three month package is an LT test which he does himself. The test and the training were available to me at the cost of one-month’s in-season fee which is a fantastic bargain. Better still, he lives just three miles away. I think the bike is where I need the most improvement, so last night; I rode over to his house.

Set Up

Upon arrival, he set got my bike hooked up to his CompuTrainer. Like my Wahoo KICKR, this is a bike trainer that electronically controls resistance on the back wheel. Most folks know the name as they were the first, and for a long time only, entrant in the computerized trainer market. In addition to using the metrics from the trainer, we also kept my Garmin paired to the Stages crank-arm power meter on my tri-bike.  The CompuTrainer was the more accurate reading since it was inputting the wattage resistance, but when I’m training on my own, I won’t have that data. Seeing the difference between power ratings on the two units provides us with a baseline for training.

While I’m very interested in science and things-scientific, it’s not my strongest area of intellect. My coach, an engineer (i.e.: scientist) by trade definitely understands this better than I do. That said, the high level summary is that lactic acid is a by-product of the consumption of glycogen. Glycogen is the chemical form of carbohydrate that your body uses when you’re performing at aerobic levels. As lactic acid is produced, some of it can actually be converted back into fuel. For some athletes, this can be utilized with great efficiency. For us mere mortals however, there comes a point at which the muscles can no longer take it and we’re forced to slow down or even stop.

There is a persistent misconception that lactic acid is the cause of muscle fatigue during and after exercise. This is not entirely accurate. The actual cause is the release of hydrogen ions into the body as lactic acid seeps out the muscle during hard efforts.

The Test

Once everything was explained to me it was time to start the test. Like any workout, this began with a warm-up which we did for a little over ten minutes. It took me a little longer than an expected to really get warmed up causing a bit of a spike on the first read. Once things settled in a little bit, my coach was able to start getting better readings.

While folks often visualize athletic testing involving an oxygen mask and a bunch of sensors all over the body, this was far less dramatic. My own heart rate monitor provided the HR data and no mask was involved.

Instead, every four minutes, he would stick my finger and then allow the blood to drip into a tiny little trough on a metal strip. That strip, in turn, was inserted into a blood monitor not unlike the testing devices used by Type I diabetics. Granted, this one was not measuring blood glucose, but rather lactate levels.

The progression involved increasing the power resistance by 20 watts every four minutes. During that interval, a new finger was stuck and blood drawn. He also recorded my heart rate at the time. So it went for over forty minutes. Normally the test would involve eight data points but he wanted to do a ninth. The reason being is that I apparently have a fairly low heart rate for the work I’m putting out. He had noted the same thing when we did my functional threshold power (FTP) test back in March. I can assure you by the end of the test I was working a very high effort levels but my HR was only about 147 BPM. I don’t have any heart condition or abnormality to explain this. It’s an interesting phenomenon and it will be interesting to see how persistent it is as we start the off-season bike workouts.

Finally, after hitting more than 260 watts 

of power (the max reading) and having the fingers on my left hand stuck a total of nine times, it was time to cool down. Of course, I still had to ride home, but that was a fairly easy ride!


Sometime later today or maybe tomorrow, I’ll have the full profile sent to me by my coach. He’ll use that to set up power-based workouts I’ll have during my off-season training. Considering that Ironman will involve more than six hours of riding, I’m glad to be getting this early jump on my training.

More posts on the results and the upcoming training will be coming soon.

Thanks for reading!

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