We gathered at eight o'clock one morning when you couldn't see your hand in front of you in the fog. From Rydebäck we ran south towards Landskrona.

The sun rose and we ran in silence as the fog lifted and changed the landscape. Mattias stopped and took one of the most beautiful running pictures ever.

In the midst of this wordless beauty, my body is a Bluetooth network. The optical heart rate monitor around my arm and the Stryd foot pod on my shoe deliver data to the Polar v800 GPS watch, which records position, stride length, cadence, distance, pace, heart rate and metres of elevation covered.  The data is processed into watts, the power my body delivers in real time. 240W at a leisurely pace along the coast.

With that information, I know how hard I can push my body for several hours without giving in, as we say, when the muscle cells don't get enough oxygen for a long time. Without oxygen, muscles work anaerobically in 'panic mode' and slowly fill up with the waste product.

The foot pod has wireless induction charging, 20 hours of battery life and weighs 7 grams. Tri-axis gyro, microprocessor and Bluetooth interface. The manufacturer Stryd sells the foot pod for $200.

Now I can track my exercise in a whole new way - power. What can my body deliver over several hours? Am I training right, what do I need to work on. And when it is race time, I can be sure I'm not pushing too hard up and downhill.

In the past, I ran on feeling and heart rate, pace and perceived exertion. Now I have a single value keeping track the right pace during training and long runs.

Most impressive is that it works. After five years of regular running, I've gotten to know my pace limits and heart rate zones for running long distances without lactic acid - the power data I get from Stryd confirms them.

It's easy to miss that the first commercial GPS receiver was the TI-4100 NAVSTAR, launched in 1981 and weighing 24 kilos.

Photo by Eric Long, Smithsonian National Air and Space Museum