roddornorn

As we discovered in the previous blog posts, digging running data from TCX files can bring plenty of insights on running performance, and maybe even current level of fitness in general. Here we'll introduce a small browser widget, which allows to dig straight into the running data, even deeper than Garmin Connect or Strava typically allow.

The key features of this particular widget are overlaying two metrics at once, smoothing noisy readouts speed or elevation, and checking consistency of specified metrics (speed, heart rate, cadence, etc) over the route sections, by means of applying basic data preprocessing techniques. All that can be done directly on the widget's webpage in the browser, no data are going to leave your device.

You can find the widget via the Tools menu of the website.

So, let's get started.

1. As the first step, upload a .tcx file with your running data. It can be exported from Garmin Connect, Strava, or other platforms. For this purpose, we'll take a tcx file recorded at the most recent our race - 20th. GO! Halbmarathon Saarbrücken, on 15 Mar 2026. For those who wants to see the data, the same activity can be found in Strava.

2. When the file is loaded, one can use the dropdown menus to select distance or time for the X-axis, and the value to plot for the left Y-axis.