2PEAK Functions Knowledge Base

Automatic interval analysis and “Training by heart rate or pace?”

In this text we look at the confusion surrounding the topic of intervals and the answers to the problems of “when is an interval an interval?” and “training by heart rate or pace?”.

An often asked question, which we get from our athletes is: “2PEAK doesn’t recognize my intervals as being intervals, something is wrong! What should I do?” Well, this “issue” doesn’t have anything to do with the athlete nor with us. The problem is the correct definition and understanding of an interval; because what makes an interval an interval?

Interval training consists of alternating phases of exertion and recovery. The interval duration ranges from a few seconds to several minutes. Each interval training session trains a specific metabolic state. The high power zone intervals in the minute range are particularly strenuous and stressful. However, the longer intervals in the development range to improve fatigue resistance should not be underestimated either.

During an interval training, your boundaries are consciously pushed. The muscles are asked to keep performing in spite of fatigue making it’s way through. Motivation for this mostly arises in race situations but can also be created in a planned interval structure. It’s helpful for athletes to be able to check the quality of their interval in some objective way. Power meters (now available for runners too) are great for these purposes because you can constantly keep and eye on the aimed for performance level and act accordingly.

Principally speaking, interval training means a predetermined workload throughout the stated time period.Therefore the goal is definitely to have this load staying constant.

But here’s where most of the confusion already begins. Your training device for example, doesn’t detect intervals but only shows the average value for chosen time periods. The problem is that an average can arise in different ways. You could also reach an average of 6 minutes in say your Z4 at 200W by doing one minute at 300W and one at 100W and then you alternate that. Sure, that’s hard as well but it’s a different kind of physiological intensity than if you did 6 whole minutes at a constant 200W. Producing a consistent effort over a given time, recover from it and repeat the same way again, is what is required. At 2PEAK we auto-detect your effort which, if it fits the designated criteria, will be classified and highlighted as an interval. If your effort is outside the tolerances (i.e. not consistent, within the designated zone or is shorter than what is defined as the minimum duration for an interval ) it will not be “counted”. This approach might not seem very emphatic but contributes considerably in helping our athletes improving the quality of their intensity training over time. The goal remains to make our athlete’s training as efficient as possible and to show where there is room for improvement. Cause having room for improvement is a good thing ;-)!

Even though the precise evaluation of your data already includes a certain tolerance, you always have the possibility to change/ increase the margins, by using the “tolerance filter” located above the graph. You can even (manually) overwrite them in your log page. Thing is, if you increase the tolerance by only a small percentage, your interval might already be recognized as such. At the same time, this shows you, how much you deviated away from the “optimal” load. Take a look below at the following example: the first picture shows a precise evaluation, the fourth interval is “missing”. When looking at the second picture you see that the tolerance was moved up to 5% and the interval is therefore “found”.

Optimizing energy preparation

Since the athletic performance is dependent on the used metabolic state, it only makes sense, to divide the training intensity according to it and stimulate them specifically based on your individual recovery situation. Dealing with all of this with the click of a button, is one of the big advantages of 2PEAK. An interval training has to be monitored, measured and later be evaluated. That’s what the different zones, which each belong to a different metabolic phase, are used for.

When you register and are lacking your numbers, we initially estimate your zones, but we recommend that you soon perform one of the simple field tests as described here: Goals We’ve noticed, that despite their simplicity, these tests are very realistic, exact, can be scheduled at your convenience, repeatable and comparable, for free and “bloodless”… and you can invest the here saved money from a test lab into more intelligent training…

Following that, 2PEAK will give you your intensity information’s according to your training zones (you can chose between heart rate, speed/pace or power in your settings). For example; 3 x 10 min in Zone 4 with 10 min easy in between. When the athlete sees this, he knows that he has to produce enough power to reach zone 4 and has then to hold the effort constantly for 10 minutes. The problem with using heart rate as an objective way of measuring, is that it reacts rather slowly and so it can take longer until you’ve reached the wished for zone even though the performance (measured in watts or speed) has already been reached way earlier. On top of that, your heart rate is exposed to external influences. If for example, your body starts to heat up during an inside cycling session, due to a lack of head wind, etc. your heart rate will move up (drift) and this isn’t due to an increase in your effort/ performance.

Why could it be that there is a difference in the evaluation of a training when using heart rate compared to power?

1. The correlation of heart rate and performance isn’t always stable, since heart rate is influenced very easily by a lot of factors.

2. With an increasing form, performance goes up but the heart rate stays the same. That’s what makes it so important, that the training zones are newly found and defined/ adjusted from time to time.

3. Short-term maximum performance can’t be seen on the heart rate data, since the hearts reaction is slightly too slow for such a short intensity peak.

Because heart rate doesn’t measure your actual performance but “only” your bodies reaction to it and is therefore very much dependent on different other internal and external factors, we recommend that more advanced athletes use the training zone definition in speed (for runners) and power (for cyclists, now new also for runners).

It’s true, our interval analysis is strict and not very emphatic but it does help athletes to a higher quality and more efficient training. All the best with it!!!