Time and time again the question arises as to which method is best suited for intensity control in training: Pace, heart rate or instinct? We discussed this complex topic with sports scientist and lecturer (e.g. for athletics and endurance training) at the Institute of Sports Science at the University of Bern, Roland Schütz.
Basically, endurance training is about wanting to complete your units in certain intensity ranges. Sometimes the goal of training is to push yourself to your limits, while other times you consciously do a more relaxed training. But what is the most suitable method for monitoring this intensity? Some people think that this is easiest with the heart rates, while others prefer to orient themselves towards the speed and again others rely entirely on their gut instinct. In this interview, we aim to explain why the different methods are difficult to compare and when which method might make more sense.
How can the heart rate and tempo values for the different intensity ranges be determined?
For both methods, the intensity ranges must first be determined individually. The main goal is to determine the anaerobic threshold (when the body can no longer break down the lactate produced in muscles, cells and blood quickly enough and it starts to accumulate). This threshold can be determined by specific tests. There are several variants. The most common are the lactate level test and the Conconi test. The lactate level test measures your heart rate values and the amount of lactate in your blood as your intensity levels increase, which can be used to determine your anaerobic threshold heart rate and speed (corresponding to the limit between intensity zones 4 and 5), your maximum pace and the heart rate and speed zones for the intensity ranges 1-5. In the Conconi test, you run a certain distance (25m, preferably on a 400m track) several times in a row, increasing the pace slightly each time. Here, too, you run until you are completely exhausted. The heart rate curve can be used to estimate the anaerobic threshold and thus determine the heart rate and velocity rates for certain intensity ranges (however, the lactate level test provides more accurate results). For an estimation of the threshold pace (not the heart rate!), a 30′-tempo run or a maximum 30-minute competition on a flat track is sufficient. The average pace of the run is a good estimate value for the anaerobic threshold.
What are the advantages and disadvantages of intensity control according to heart rate?
Advantages: Heart rate control is particularly suitable for zones 1-4, where the heart rate increases linearly with increasing intensity and a relatively wide heart rate range can easily be assigned to a certain intensity range. The heart rate also tells me in hilly terrain or in headwinds whether I am loading in the desired intensity range. The estimation of training loads on varied routes is thus possible.
Disadvantages: Interval trainings in zone 5 can hardly be controlled with heart rate, because the heart rate always lags a moment behind the load (the shorter the loads, the more difficult). In addition, the HR is always in the range of HRmax anyway at the end of interval training in zone 5.
What are the advantages and disadvantages of intensity control according to pace?
Advantages: A speed control makes sense if you want to determine your position (i.e. like saying: “today it was easy for me to run at this speed”). If you train for a certain competition goal (e.g. half marathon under 1h 30min), you can set clear speed targets for the intensive training on a flat course. During interval trainings (zone 4 and 5) you can set clear speed targets, or at least you can check whether the speed can be maintained up to the last load. This way you learn how to ration your energy.
Disadvantages: The intensity control with speed only works with a standardized lap, so that I can compare my run time, or on a flat course. On flat tracks I need a GPS clock or measured track markings. The accuracy of GPS watches for me is not yet beyond all doubt. The displayed instantaneous speed is often not correct (with my not quite cheap watch, deviations of up to 50 seconds per kilometer at constant pace are not uncommon…). On the other hand, average speeds over longer distances are quite good. Running by pace can also tempt you to try to set a record on your laps every time or to get a certain average mileage (even if you are in bad shape or in unfavourable conditions). This can tend to lead to too high intensity even for basic training.
The issue with the flat track also applies to heart rate control. Do I have to slow down the pace uphill so that the heart rate does not leave the desired intensity zone, or can I compensate with a below-average heart rate downhill?
If you want to stay in the intended intensity zone, you have to slow down and possibly even march. Uphill you are quickly in zone 3. This has to be considered when planning your training (consciously plan the basic training on hilly or flat tracks). Compensation is not possible. The average heart rate of a training on a hilly track doesn’t really say anything. Otherwise you could also compensate a tough interval training by the low heart rate in the breaks and when running out and it would suddenly only be a medium hard training. But that’s not going to give you accurate results.
BY THE WAY: In our running.COACH app there is the GAP function (“grade adjusted pace”), which converts the speed of your training lap to the pace you would have run on a completely flat track. This way you can easily compare your performance on different tracks! Have a look at the value on the right in the screenshot below.
What kind of intensity control do you suggest if you want to succeed in a race?
If you want to monitor a competition by heart rate, it only works for the first half of the competition. This way you can prevent starting too fast. In the first few minutes, however, you need to have a sense for the intensity, because at this point the heart rate does not always correspond to the performance. In the second half the heart rate is no longer a reliable control factor. Among other things, this is due to the so-called “cardiac drift”. The term stands for the increase of the heart rate with constant effort, caused by factors such as increased heat in the body. In principle, as for the competition tactics (concerning the rationing of your energy) on a flat track with no wind a control of the pace is suitable. If, however, after the first kilometer you notice that you have started much too fast, you will pay for this in the further course of the competition.
Is one option more suitable for beginners and another more suitable for advanced athletes?
If we assume that beginners do not immediately start with intensive training (rule: first increase the number of training sessions, then the length and only then the intensity) and do not yet have a good sense for intensity, heart rate control is suitable for them. It presupposes, however, that the ranges are individually determined as described above. Rules of thumb such as HRmax=220 age are useless in individual cases. For advanced users I would recommend: Primarily to train the personal sense for intensity, to control basic training from time to time with HR, from time to time – on standardized distances – also with speed. Interval training should predominantly be done with speed control. In general, an exact adherence to certain intensity ranges is less important for beginners than for athletes with a lot of training.
Conclusion:
Both heart rate and pace do not take into account fluctuations in daily form or external conditions (e.g. heat, distance profile) enough. It would be better, as running.COACH recommends, to develop your sense of intensity so well that you can feel which intensity range you are running in. If you have a good body awareness and/or some training experience, you can usually do that well. However, heart rate and speed control can be used to check this sense of intensity. In basic training (zones 1-3) the instinct can be well supported by heart rate control (the pace can be an interesting additional information) and in intensive training (zones 4-5) it can be well supplemented with speed control (there the heart rate is the interesting additional information). Performance changes at constant heart rate or heart rate changes at constant pace can give longer-term indications of progress or problems (e.g. deficiency symptoms or overtraining).
If you train with running.COACH, you do not have to worry about whether you train sufficiently in the different intensity ranges, because running.COACH automatically calculates the optimal intensity mix for you (regeneration run, endurance run, interval, average speed, long jog). As long as you have filled in the settings correctly and your training is according to our recommendations, the different intensity ranges in your training are covered.
Roland Schütz is a 57-year-old former middle- and long-distance runner (personal best time at the Grand Prix of Bern: 51:24), today an orienteer. He is also a long-time trainer in medium and long distance running in the ST Bern, advisor of orienteering cadre runners for running training and lecturer at the Institute for Sports Science at the University of Bern (athletics, endurance training, performance diagnostics, etc.).
Edited by: Marion Aebi, Translated by: Denise Kaufmann
