Your fitness is constantly changing, with every workout, every break, every illness. So that you don’t just feel this development but can actually see it, running.COACH gives you the Fitness Index, available in the app and on the web.
What the Fitness Index shows
The Fitness Index is an ongoing estimate of your current form, based on your most recent activities. Unlike a single test result, it shows you a development: are things trending upward, are you holding your level, or are you losing form? After every activity, running.COACH estimates the performance behind it. The index itself is a weighted average of these estimates over the last 60 days, with your most recent activities weighted the most heavily.
Because the Fitness Index averages every snapshot over several weeks, it can sometimes drop during intense training blocks, even though you’re actually training hard and a lot. This affects advanced and ambitious runners in particular: if you come out of your sessions more tired during a hard training week, that affects the individual performance values, even though your basic fitness is actually rising. This is a normal effect of the smoothing.
If you don’t train for a while, for example because of a break or illness, the index doesn’t automatically keep dropping. If you’re missing up to 7 days of training data, the value stays at the level from the start of that break. In the case of a longer gap of more than 7 days, a dashed line shows you a simple interpolation between the value before the break and your first result afterwards. So no loss of form is assumed just because you’re not training at the moment.
Fitness Index and performance level: two different things
Your performance level is the value your training plan is built on. It determines the paces you train at, and it determines which race time the plan predicts for you. The Fitness Index, on the other hand, shows something different: what you’ve actually achieved in the past few weeks.
Let’s say your plan is currently based on a certain performance level. If you’ve been running stronger for a few weeks than the plan assumed, your Fitness Index climbs above this performance level. So it shows you: you’ve now come further than the plan assumed.
If, on the other hand, you’re ill for two weeks and then start again cautiously, your Fitness Index drops, while the performance level as a planning value initially stays the same. At that moment, the plan demands more than you can currently deliver.
In the end, the two values complement each other: the performance level shows you what your plan is steering towards. The Fitness Index shows you where you really stand right now. The Fitness Index reacts immediately to every single workout, while your performance level deliberately stays more stable and only changes over a longer period. This way, the Fitness Index gives you an honest picture of your daily form, while your plan isn’t constantly rebuilt because of individual particularly good or bad sessions. By the way: when training data is missing, the performance level is handled differently from the Fitness Index; there, running.COACH uses its own interpolation for the performance prognosis.
You can find out in detail how your plan actually processes this development in our article on the dynamic training plan.
What this means for your training
The Fitness Index isn’t a value you should look at in isolation, but a tool for putting things in context:
- If your index rises continuously, it shows that your training is working and your form is building up.
- If it stays stable, you’re holding your current level, which — especially during intense training phases or in everyday life with little time — can already be a good sign.
- If it drops even though you’re training a lot, you may be in the middle of a hard training block. This is normal especially for advanced runners and no cause for concern, as long as you don’t feel overloaded.
- If you don’t train at all for a while, the index simply stays put during short breaks; during longer ones it’s interpolated up to your next workout, but it doesn’t drop on its own.
Important: a lower index doesn’t automatically mean that something is going wrong. Especially during intense training phases, it’s more of a hint to pay good attention to your recovery than a sign that you need to do more.
Where to find it
You’ll find the Fitness Index directly in the app and on the web.
- App: under the Analysis -> Performance tab
- Web: under the Analysis -> Running-Fitness tab
