Changed something, fitness become red

Hey there, great platform and community here, love it and I weekly suggest to other cyclists! I have been using Intervals.ICU more and more lately as I purchased a power monitor (2w) for my road bike and cycling is my only sport (I do limited weight training to help with bike/age 47).

I had a overtraining (more like newbie overcooking) last year and I am always scared of the redline.

My training seemed fine and progressing for the past 2-3 months with a professional coach help. Very few exceptions reaching the Fitness red danger zones (1 in the past 4 weeks)

After trying to sync my heart rate zones from Intervals to Strava and Garmin (it keeps auto messing around my zones!) I was really exploring all the screens here and something really weird happened as you can see from screenshots bellow. .

What I remember of changing was fitness from absolute to percentage.

What could I have done to completely mess up my data like that ?

1 Like

First image is absolute fitness
Second image is % of fitness

Look at the form (TSB) number on your fitness graphs. Change it back to Absolute and you will see that it reverts back to “normal”.

Rather use your ramp rate to guide “too much training, too quickly”.

1 Like

That’s great news and help, thanks a lot @Gerald !

Once overcooked, always afraid of overcooking ! It’s my 1st year with disciplined training and I still get confused about “progress”.

If you may, a quick question :

While looking at % of Fitness seems more appropriate in a on going basis (if your data literacy is up, I work with data on my job) and I do understand why an absolute number may seem more practical for most people to see if 50 is bigger than 40 from 3 months, altough nothing is simple in data or fitness.

But Why changing the scale, changes the results of Fitness range ? I can’t come up with a logic for that …

The absolute number is an old, but trusted, way to measure Form (aka TSB or Training Stress Balance in TrainingPeaks). It’s a measure of how much an athlete trained recently (Fatigue, aka ATL in TrainingPeaks), compared with how much an athlete trained historically (Fitness, aka CTL in TrainingPeaks).

From TrainingPeaks.
TSB is not as a predictor of performance but as a measure of how adapted an athlete is to their training load.
Form (TSB) = Yesterday’s Fitness (CTL) - Yesterday’s Fatigue (ATL)

The % of Fitness method is related to your zones. I’ll be honest and say that I don’t know as much about it as I should. I’m old school, and can tell you if you’re over training based on what I know, or have been taught, using CTL, ATL, TSB, ramp rate, TSS, TIZ, RPE and Feel, and perhaps a few other metrics not listed.

I prefer the Absolute value, as I also use WKO5 for all my athletes, which is where this originated. Intervals adds more value than TrainingPeaks does, which is why I’m here for the integration with my athletes.

1 Like

@Gerald it’s so nice to see the bike community sharing and connected world wide ! Thanks for the kind explanation and personal insights. I always try to give back to other cyclers that kind of kindness I got.

And just as an off topic note, regarding your experience of absolute x percentage, you have much more experience and is probably right on your preferences. I am still learning so much and also having fun on my fitness, on cycling and this quantified self world of data. And after I’ve read this book How to Lie with Statistics - Wikipedia ( due to my job, it’s a classic for STEM students ) I tried to create habits to prevent myself of my biases. It’s not foolproof (our brains are lazy) but sometimes it helps. From my 1st year cycling (saving data ) I was addicted to the absolute number, now I am more oriented to a steady, sustainable progress, where the absolute number will likely increase, but finding the flow is the main goal.

I will see you around !


Enjoy your training. Having fun results in wanting to more of it, more often than not.

Don’t get too carried away by the numbers, but rather learn how the training and racing efforts feel. We, humans, aren’t robots capable of doing the same thing, over and over, without some form of deviation.

Even though I use the absolute number, it’s a guide and not exact.

1 Like

Here’s my training plan up to the end of November, the first A-race of my season (southern hemisphere). I have shown both Absolute (left) and % Fitness (right) to show how there is very little difference between both options.

If all things go to plan, this is easily achievable for me and something I’ve been doing for close to 18 years. Perhaps a little less racing now, compared to before covid. The C-race is a fun 4h MTB ride, but the B-race is a little more serious.