Body Temperature As Performance Indicator


While measuring you heart rate when exercising gives you a certain level of insight into your performance, it doesn’t give you the complete picture. That’s because particularly in extreme heat, body temperature has a direct influence on both your vital signs and level of performance. To get around the possibility of misleading vital statistics, Munich-based startup Cosinuss created an in-ear wearable that not only measures your heart rate and its variability, but also your body temperature, sending all the data via Bluetooth to your phone or other devices in order to optimize your training and competitive performance.

The Cosinuss One is a lightweight, comfortable, in-ear wearable much like a hearing aid that continually monitors your vitals. It accurately records your heart rate without the need for a chest strap or watch and also monitors your body temperature to see how it is coping with both exercise and the environment.

Body temperature is a highly relevant parameter for determining or influencing physical performance.  The most obvious interpretation of high body temperature is overheating. Once your body is overheated, there is no easy way of recovering through hydration or other cooling actions. Your body needs a rather long recovery time to reach the normal level of performance again. The key obviously is to prevent overheating in first place, which you can do by continuously monitoring your body temperature and associated  dehydration level. The Cosinuss One and corresponding app informs you of your dehydration level using a color system. When a dangerous zone is entered, actions need to be taken in order to prevent overheating.

Another use of continuous body temperature data lies in the increased accuracy of other performance measures. Body temperature exerts significant influence on your heart rate. Your heart rate increases almost proportionally with performance when you start exercising. Thus, in this initial period there´s a very good correlation between heart rate and performance which makes heart rate a legitimate parameter for training.

This, however, changes when your body temperature rises above normal, and the life-sustaining cooling process of your body kicks in. Cooling is primarily achieved through perspiration and heat emission. If there is more heat to be dissipated than normal, the main blood circulation increases to eight to twelve times its normal rate. Consequently, your heart has to beat more often and so heart rate increases. This increase in heart rate, however, is not caused by performance but solely by the cooling process.

I experienced this is Sri Lanka where at one point, my heart rate maxed out even though I was pedaling slowly along a flat section of road. I would have loved to know that I was on the way to overheating well in advance of reaching this crisis mode.

The Cosinuss One retails for €150 and is available from the company website.

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