Functional threshold power (FTP) tests have been used by cyclists to determine the highest sustainable power a rider can maintain for rides/races lasting anywhere from 30-90 minutes. Detailed - here - FTP is determined by either 90 or 95% of the power maintained for an 8 or 20 minute all out ride, respectively.
More recently, a variable, critical power (CP), has been used to determine the highest wattage a rider should be able to maintain for 30-60 minutes. However, determining CP requires an athlete to complete 3-5 all out tests ranging from 2-15 minutes. These results are then plotted onto a wattage vs time graph and the asymptote of that curve is the CP. From this graph, buffering capacity, or W’ can be determined and represents the non-aerobic gas tank the athlete has.
While CP tests provide more useful information than a simple FTP test, they require a lot more effort, and multiple days of testing. To remedy this, a research group from the United Kingdom, created a 3-minute all out test that has the ease of one test, with the in-depth data of a series of critical power tests (Vanhatalo et al. 2007). While this test is a maximal 3-minute effort, it’s creators have shown that this test is robust and sensitive enough to detect changes in CP in a wide variety of athletes.
One of the major criticisms of a 3-minute CP test is that its original design makes it extremely specific to one cycle ergometer and because of this it is unable to be used in a wide variety of sporting modalities. However, researchers have used this test across a variety of sports including rowing, and readily available cycling power meters. While the debate of the efficacy of this test remains for its general applicability across many different sports, its potential to replace other tests cannot be overlooked.
If you are a coach or an athlete reading this and want to give this test a try, it must first be noted that this test is ALL OUT, in order to get valid data the rider must be highly motivated to ride as hard as possible for 3-minutes. This requires a proper warm-up and some accelerations in order to get the body properly primed to handle the effort.
3-minute CP test protocol:
*For maximum applicability the following protocol has been adapted from (Francis Jr. et al. 2010)
If wearing a Moxy, warm-up until SmO2 is as high as possible – if you are unfamiliar with using Moxy to dictate your warm-up click here for more details.
After warming up, begin the 3-minute all out test by shifting to the gear that will allow you to get the highest power output, ride as long and as hard as possible, shifting gears so that by the end of the three minutes you’re pedaling at your preferred cadence. Typically between 80-100. Average the last 30s of the 3 minute test and use that as critical power, it’s as simple as that.
In the next blog post I will detail my experience with three, 3-minute critical power tests, I will detail the results, and analysis, and I will detail the potential for Moxy SmO2 values to be used in lieu of heart rate or power values to dictate racing.