'My Training' explained
The 'My Training' graph is a visualization of a few basic training metrics over time: running stress score(RSS), moving time, distance or elevation. Additionally, changes to your Critical Power are mapped to identify changes in your fitness with the green and red triangles.
The default, RSS, is a single number meant to help you understand how your day-by-day training contributes to your fitness. It quantifies how much you’ve trained, and takes into account the variety of intensity in your training.
RSS is relative to your Critical Power and won’t show up until you have generated a CP. Typically after three runs. Here is the equation:
RSS = 100 x training duration x (Power/CP)^K
Equations aside, RSS is a point system that awards a certain number of points to each of your runs based on your intensity and the duration of the run. The higher the intensity (percent of your CP), the more RSS/min you generate.