Interval training for dummies …. but also for smart people.
When offering a workout, the expected training effect is central. This assignment can be presented as an endurance- or interval format, and the choice depends on the intended intensity. For example, an interval format will be chosen if the required intensity exceeds a certain limit, meaning that anaerobic energy production must contribute to the effort. Offering a training assignment as an interval format allows for a longer retention time at the given intensity, thus enabling more work to be performed than when performed as an endurance training assignment. The result is obvious: the expected training result will be higher.
Modern training theory uses Accumulated Work Duration, abbreviated to AWD, as an objective measure for estimating the training effect. However, AWD is determined by many variables. Naturally, by the duration and intensity of the single effort, but also by the intensity of the rest period, the ratio of work time to rest time, the number of repetitions per set, the number of sets, and the duration and intensity between sets. In other words, many variables that, due to varying input, constantly place different demands on the body. Choosing the right interval training format is like playing the lottery: the chance of creating the winning combination—the desired workload for your goal, in this case—is extremely small. This powerlessness is also evident among online training schedule providers. The most absurd assignments are often as follows:
• Ride intervals of 30 seconds to 5 minutes at a high intensity.
• Rest for 1 to 2 minutes.
• Try 3 to 6 repetitions.
• The intensity is such that your legs "burn."
They then add: “as your condition improves,” you can increase the intensity. I wonder: does that mean you have to have third-degree burns on your legs?
Applications that take themselves a bit more seriously use effort- or training zones as a framework for designing interval training. This brings us to the concept of Functional Threshold Power and the division into zones based on % FTP.
It's a mystery to me why, given current knowledge of exercise physiology, this method remains so popular. It's probably due to the premise that "the more you repeat it, the more credible it is." Repetition creates a sense of familiarity and thus creates an illusion of truth.
Whether you buy into the FTP narrative or not, it's still a matter of guessing which energy system is taxed to what extent for a given interval format. Yet, this knowledge is crucial for the expected training results. The Training Stress Score, introduced years ago to measure the stress of exercise, also offers no solution. After all, it can give an identical score to completely different forms of effort. So much for "interval training for dummies."
The Extended Critical Power concept, developed by Professor C. Dauwe and thoroughly discussed in his latest book,
offers an innovative perspective on the physiological demands of a given effort. Besides illuminating effort zones,
there's a key application: the interval training module.
This module is unique because it displays a preview of the precise physiological demands of the selected interval format, thus providing a clear picture of the expected training effect.
The following examples demonstrate the power of this application. They are even more powerful because they also consider the individual rider's recovery potential via the Individual Recovery Index (IRI).
Let it be clear, our tool doesn't tell the coach what's best for their athlete; it helps him make informed decisions.
In the examples below, the coach chooses interval training that stimulates VO2max.
He first chooses a VO2max training with an intensity in the middle of the VO2max zone and wants to know the effects of the same exercise on two cyclists with roughly the same maximum power output but different recovery levels. For athlete A, with an IRI = 0.7, this specific format requires almost 12% anaerobic contribution but allows for three repetitions, after which he still has approximately 10% anaerobic energy remaining. Consequently, the AWD is 12 minutes, or almost twice as much exercise time as if he hadn't performed the exercise as an interval.
However, athlete B, with poorer recovery (IRI = 0.3), cannot complete the third exercise because his anaerobic energy balance falls to zero even after the second repetition.
If we adjust the effort/rest ratio for cyclist B from 2/1 (format as above) to 1/1 (format as below), then even 4 repetitions are possible and he also has 10% anaerobic energy to spare. As a result, the AWD even increases to 16 minutes.
The possibilities of this module are endless, but here's a question for further consideration
How do different intensities, within the same zone, influence the result?
To answer this, we'll give athlete A two additional tasks. We'll keep the same format but vary the intensity. Once with a value at the lower end of his VO2max zone and once with a value at the upper end of that zone. A VO2max task at 430 W and 465 W, respectively.
At an intensity of only 430 W, the anaerobic contribution falls from 11.8% to just 7.7%, leaving him with 40% anaerobic energy.
An intensity of 465 W produces a completely different result. The anaerobic contribution almost doubles. So much so that even the second repetition will have to be stopped prematurely.