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Heart rate, speed or watts? What you opt for depends on the intensity of your training.

In the past, it was easier to control the intensity of a training session. You relied on how your body felt, ran a certain distance in a given time, or controlled the intensity by the type of breathing you used (mouth, nose, or combined breathing) or the number of words you could string together before you had to breathe again.

Today we have many more options: hardly anyone runs or cycles without a GPS watch and, in addition to information about the distance you have travelled, it always displays a wealth of information, from heart rate and speed to performance. As a result, we pay far less attention to our bodies’ signals and instead blindly follow the data.

Which display for which type of training?

In principle, it would be ideal if you could achieve your desired intensity without any aids. That is, if you had developed your sense of speed to the point where you could rely on it, even in competition and under the influence of adrenaline. However, evaluations of interval times show that this is not so easy at all, and amateur runners tend to misjudge their effort somewhat. They usually start off too fast and gradually tail off towards the end. Those who can pace themselves well, on the other hand, start off more slowly and then make up twice as much in the end.

In training, this is easier to practise and implement. Those who train regularly, incorporate different forms of training and, for example, always take care to complete the second half faster, develop a good feeling for the different intensity ranges and can get more out of the training session.

Those who like to exercise under a controlled effort should pay attention to the following recommendations

Basic effort (zones 1 and 2): heart rate

For training sessions designed to develop basic endurance, it is recommended to use your heart rate as a guide, since metabolic states – the actual goal of the session – are only trained up to a certain heart rate. If your heart rate exceeds those values, it defeats the actual goal of the session. For this reason, it is also advisable not to run or cycle at defined speeds or wattages in zones 1 and 2, because it does not help if these values are reached, but your heart rate is too high. Therefore, the lower the intensity, the more important the heart rate is.

Medium speed (zone 3): speed and watts

If you train at a medium intensity and are trying to improve aerobic capacity, running speed and cycling wattage becomes more important, because the heart rate matches the exertion too slowly on the one hand, and gradually increases during exercise on the other, despite the intensity remaining constant. This phenomenon, known as cardiac drift, is affected by various factors such as fluid loss, increase in body temperature, or fatigue. Therefore, the higher the intensity, the more reliable the running speed and wattage on the bike.

High Speed (zones 4 and 5): speed and watts

If you are training at a high intensity, in your anaerobic threshold zone and above, you should also use speed and watts as reference values. It simply takes too long for the heart rate to adapt to the effective performance during intense exertion. Therefore, you should rely on speed when running and on wattage when cycling during intensive exertion.

Conclusion

Over time, we have become somewhat dependant on technological aids. Instead of training based on how our body feels, we all too often trust the numbers of heart rate monitors, GPX devices or wattmeters. However, these tools are important guides for beginners and can also be used to make themselves redundant in the course of your personal sports career, if you assign your own body feeling to the numbers and different intensities.

When looking at the data, heart rate monitors are a good companion for low-intensity effort. At higher intensities, they are outweighed by the advantages of speed and wattmeters, or even a well-trained body feeling.