The training load page used to have a big table full of numbers. It’s now a lot prettier:

This chart shows what riding one has been doing over time in a way that can indicate one’s ability to perform. The following ideas are key to understanding this chart:

• Training load (TL) — a measure of the overall effort of a particular ride. Individual rides aren’t presently shown on this chart. Having a correctly set FTP is very important for this chart to be meaningful.
• Long-term stress (LTS) — the long term average training load. This is what the body is used to doing. Higher values typically correlate with higher potential performance.
• Short-term stress (STS) — the short term average training load. This is what the body is currently doing.
• Stress balance (SB) — the difference between LTS and STS (before the ride). This indicates freshness (for positive values) or fatigue (for negative values).

Therefore, in preparation for an important race, it is ideal to have a high LTS (after lots of training in the previous months), but a low STS (after tapering) and consequently, a positive SB. The exact numbers that work best in practice varies from athlete to athlete, so experimentation is required, but this chart makes it possible to quantify them.

For the mathematically inclined, the long-term stress and short term stress values are calculated as exponentially weighted moving averages. The following formulas are used:

Today’s LTS = yesterday’s LTS + (today’s TL − yesterday’s LTS) × (1 − e^(−1/42))

Today’s STS = yesterday’s STS + (today’s TL − yesterday’s STS) × (1 − e^(−1/7))

Today’s SB = yesterday’s LTS × e^(−1/42) − yesterday’s STS × e^(−1/7)

Therefore, the stress balance for a day is calculated without including any rides that happened on that day. Speaking of rides, if there are multiple rides on a day, the training load values are added together.

The concept of this performance management chart was originally developed by Andrew Coggan.

One other minor change made recently is that the main ride graph now also shows how many metres of climbing have been done in the current selection. That’s all for now. Expect to see some more analytical charts in the very near future…