Training practice part 3: High Intensity DECREASING Interval Training
Frank Vandewiele
Goal
In the previous blog, we defined the VO2max zone as the intensity range between SCP and P5. We also drew attention to the fact that the anaerobic input should not be underestimated, with a negative impact on endurance time. If a rider still wants to keep that effort time high when using such high intensities, the High Intensity DECREASING Interval Training can offer the solution.
A well thought-out adjustment
Using the "classic" interval formats has both advantages and disadvantages. We briefly summarize the points of attention.
· Medium intervals allow the athlete to reach the VO2max (or rather the VO2peak) relatively quickly where, however, he has to take into account the effects of glycolysis which become more and more pronounced as the effort is prolonged. Indeed, above SCP, all additional energy is supplied by the anaerobic system which strongly increases the Fast Death Load per unit time. (https://www.kobo.com/ebook/the-future-of-training-and-racing-with-a-power-meter)
· To extend T@VO2max, several studies indicate that short intervals are beneficial. However, the “Time to reach VO2max” comes into play here, so that intervals that are too short do not reach the target of at least 90% of the VO2max (fig. 1 from our previous blog). Indeed, oxygen kinetics mean that - depending on the individual - it can take more than 1'30" to reach VO2max. Important: this concerns a one-off effort “to the limit of tolerance”. With successive efforts, however, we get a different story (fig. 1). The oxygen system is, as it were, “warmed up” so that at the start of the next repetition it takes less time before the VO2 peak is reached.
Fig. 1: Oxygen kinetics at successive efforts
The High Intensity DECREASING Interval Training cleverly responds to previous observations and uses the benefits of both medium and short intervals to achieve the training goal.
HIDIT based on time intervals
This is the classic way in which it is assumed that both effort and rest times will elicit the desired effect.
· The training starts with an effort of, for example, 3' or 4' at an intensity above SCP so that we are sure that such intensity will trigger the VO2peak. Moreover, the exercise duration is sufficient to compensate for the “inertia” of the oxygen supply.
· The other side of the coin is the sharp decrease in the anaerobic reserve that accompanies this and therefore necessitates recovery. On the one hand, this recovery should not take too long to ensure that the oxygen supply remains at a decent level, but should also allow the anaerobic reserve to return to an acceptable level. Research shows that in the first part of the recovery, the reserve is replenished fairly quickly, so that the chosen short recovery time in function of the oxygen kinetics is also sufficient for the reconstruction of W'. We actually kill two birds with one stone.
· Despite the fact that the recovery of W' is fast, a short rest may not be sufficient to achieve a full recovery. Thus, the subsequent load must be slightly reduced because we now no longer have a fully charged system.
· Decreasing thus means that at the same intensity, the effort duration decreases more and more. It drops from an interval of medium duration to one of short duration.
A frequently recurring format in the literature is listed below. 1 series consists of:
1 * 3’ / 2’ R
1 * 2’ / 1’ 20” R
1 * 1’ / 40” R
x * 40” / 30” R
We had one of our riders perform this HIDIT at an intensity just below the upper limit of his VO2max zone and analyzed the data using the “Typhoon” program by C. Dauwe D.Sc. (fig. 2) (https://www.typhooncycling.org).
The upper half of the graph shows an enlargement of the energy balance of 1 of the 3 series.
Fig. 2: HIDIT at set time intervals
The questions to ask ourselves as coaches are:
1. Does this training meet the stated objective?
2. What adjustments, if any, can be made?
The first question cannot be answered with a resounding yes because no oxygen recording equipment was used. Thus, we do not know exactly how many minutes of these efforts were performed at 95 - 100% of VO2max. However, using the intensities and methodology described above and in our previous blog, we can claim with a high probability that this training was targeted.
The second question will have to be answered by the rider or his coach as a function of the overall picture and as a function of the profile of the targeted races.
From the data of the upper half of the graph, the following adjustments can be considered:
(a) Do not use 3', 2', 1' .... as effort duration but use 4', 3', 2', 1' .... because the balance can actually drop deeper and there is room to extend the effort duration. After all, after the first repetition it appears that 40% of the anaerobic reserve remains and after the second even half is still available.
b) Reducing the rest time will keep the VO2 at a higher level but at the same time allow the W' balance to drop deeper.
HIDIT on the basis of W' balance
Since the anaerobic widget in the SuperCycle app (https://www.sportim.be/supercycle) allows the performance to be monitored "in the action," it is possible to control the format of the HIDIT via the anaerobic energy balance and not via the classic exercise and recovery duration. With such a way of working, the athlete can adjust the load even better to his needs or objectives and can even calculate the anaerobic load in advance in function of the chosen training intensity by using our training modules. (www.sportim.be)
The task can then look like this: (Fig. 3)
1° repetition lower the balance to 30 %
2° repetition up to 40 %
3° repetition up to 50 %
And all further efforts up to 60 %
After each effort, W' should be replenished to, say, 70 - 80 %.. (www.sportim.be)
Fig. 3: HIDIT based on the W' balance