Computrainer Training Classes FTP Threshold Testing

The term “threshold” has become synonymous with the word “confusion” in the minds of many athletes. There are many different words for essentially the same thing: anaerobic threshold (AT), lactate threshold (LT), maximal lactate steady state (MLSS), onset of blood lactate (OBLA), and just plain old “threshold.” It seems that there are just as many possible definitions, with different versions of the concept based on heart rate, blood lactate, wattage, and so on.

For more than thirty years, exercise physiologists have known that the exercise intensity at which lactate begins to accumulate in a person’s blood—that is, his or her functional lactate threshold (LT)—is a powerful predictor of that person’s endurance performance ability. This is because although an individual’s cardiovascular fitness—that is, his or her maximal oxygen uptake (VO2max)—sets the upper limit to his or her rate of aerobic energy production, it is the individual’s metabolic fitness—that is, LT—that determines the percentage or fraction of this VO2max that he or she can utilize for any given period of time.

Determining Functional Threshold Power

So, how do you go about determining your functional threshold power? One way is via laboratory testing with invasive blood sampling, but few people have access to such testing on a regular basis. In addition, power at LT as determined in this manner is often significantly below what athletes and coaches tend to think of as a “threshold.” A more convenient and possibly more accurate way of determining your FTP is to simply rely on data collected using your power meter in the field. There are a number of different ways to do this, each of which has its advantages and disadvantages, but all of which provide very similar estimates of threshold power.

We believe that the best way is to do a ride specifically designed to find your threshold, such as the one we provide at the Peaks Power Training Center at Parvilla Cycles.

The Threshold Test

The purpose of this initial test is to do a ride where you can average the highest watts that you can for a substantial period of time.

Your goal in the main portion of the test, the 20-minute segment, is to produce the highest average watts over the entire period. It’s not a good test if you go out too hard and suddenly run out of energy, because you will not be able to produce your true maximal steady-state power. It is always better to start out in the first 2 minutes a little under what you believe to be your FTP, build up along the way, and then ride at your maximum level in the last 3 minutes.

Once this test is over and we download the data, to figure out what your average power was for the entire 20-minute effort. Then we will take this number and subtract 5 percent from it. The number that results will be your functional threshold wattage value. So, for example, if you average 300 watts for the 20-minute time trial, you would calculate that 300 x 0.05= 15, and 300 – 15 = 285. Thus, your functional threshold power is 285 watts.

The reason for subtracting 5 percent of the watts from your 20-minute test is that FTP is defined as the highest average wattage or power that you can maintain for 60 minutes. Because most athletes have a hard time focusing for 60 minutes on a maximal effort, and those who can learn very quickly that a 60-minute time trial is not that much fun, we have found that 20 minutes is more realistic in terms of getting athletes to do more regular and higher quality tests. Since 20 minutes is a shorter time period, it incorporates more of the athlete’s anaerobic capacity, however, and this skews the wattage data by about 5 percent over a 60-minute effort. By subtracting that 5 percent, you will come up with a wattage number that would be very close to your 60-minute power measure.

Now that you know your FTP, you can determine your Power Training Levels.