What is this?
This chart shows what riding has been done over time in a way that can indicate the ability to perform. The orange line, short-term stress (STS), is a measure of how much riding has been done recently, while the blue line, long-term stress (LTS), indicates what the body is used to doing. The difference between them indicates freshness (when STS is lower than LTS) or fatigue (when STS is higher than LTS). The difference is also shown as the grey line, stress balance (SB). The amount that LTS has changed in the last week, ramp rate (RR) is optionally shown as the green line. The total load for the day is shown at the bottom in the grey columns.
To use this, zoom in by double-clicking and pan by dragging the mouse left or right, or just use the controls at the top right. Click on the chart to freeze the information box, which makes the links to individual rides clickable.
Switching to draw mode makes the mouse set the training load for the day based on where you click. Clicking above zero on the main area of the chart or in the daily load section at the bottom of the chart sets the day's load to be the value shown on the y-axis. Dragging makes it easy to set multiple days at once (although if you're zoomed out too much or move the mouse quickly it can miss days), and dragging to below zero sets the value to zero. Dragging, when began below zero, pans the chart. None of this is saved. This is a quick and easy way to see how different loads affect what this chart looks like.
The STS, LTS, SB and RR values are shown as they are at the end of the day, so they will include the contribution of any rides ridden that day.
What is this based on?
This chart uses either power data or heart rate data. In both cases the data for each ride is converted into a number that indicates the stress of the ride. For power data, the training load of the ride is calculated. For heart rate data, the training impulse (TRIMP) of the ride is calculated. Both of these metrics are the product of the overall intensity of the ride and the duration of the ride. Note that the TRIMP and training load numbers are different and can't be directly compared.
Training plans are shown on this chart when they're on today's date or later. The load parameter of plans is interpreted to be a TRIMP or training load value (whichever this chart is using). For dates after the present day, the lines become dashed.
By default, this chart shows power data (and TRIMP values are scaled to approximate training load values; see below) if possible, or picks either power or heart rate data depending on what is available. The data source can be manually set by clicking on configure above.
What does this say?
This chart has a variety of uses.
- As stress balance quantifies fatigue/freshness, one obvious use is for tapering before an important event. The general idea is to get a positive stess balance before an important event, and more specific targets (i.e., hold +20 for three days beforehand) can be worked out.
- It can be used to learn how fast a training workload can be increased.
- Long-term stress quantifies workload over time, which makes it possible to compare workloads at different times.
One of the challenges is that using this to its fullest potential requires an understanding of how the individual's body responds to different situations — that is, the optimal numbers vary from athlete to athlete — and it takes time and effort to learn this.