WTF is TSB?
Training dashboards love throwing acronyms at you. Flott translates them into three words you already understand: Fitness, Fatigue, and Form.
You just synced your watch. You open your training app. And there they are: CTL, ATL, TSB. Three acronyms. Zero explanation. You close the app.
Sound familiar? You’re not alone. These metrics are genuinely useful — they’ve been used in exercise science for decades. But most apps just dump the numbers on you and expect you to figure it out.
That’s why Flott doesn’t show them at all.
Forget the acronyms
Here’s what Flott shows you instead:
No acronyms. No raw numbers. Just three words and a status you can understand at a glance — before your morning coffee.
Under the hood, these are CTL, ATL, and TSB. But you don’t need to know that. Flott’s simple mode translates the math into language that actually helps you make decisions.
Three words, one question
All three metrics answer a single question: should I train hard today, or take it easy?
Fitness is how much training your body has adapted to over the last few weeks. It moves slowly — you build it session by session, and you can’t cram it.
Fatigue is how much you’ve loaded on in the last few days. It moves fast. Three hard sessions in a row? Fatigue spikes. Rest day? It drops.
Form is the balance between the two. It’s the one that matters most day-to-day.
Fitness is your engine. Fatigue is the weight on top of it. Form tells you if the engine can breathe. When Form is positive, you're fresh. When it's deeply negative, you're buried.
What Flott actually shows you
Instead of a number like “-16.4”, Flott gives you a zone:
| Zone | What it means | What to do |
|---|---|---|
| FRESH | You’ve got legs | Go for quality — tempos, intervals, long runs |
| ABSORBING | Balanced load | Normal training, stay the course |
| BUILDING | Fatigue stacking up | Dial it back, easy sessions only |
| OVERREACHING | Deep in the red | Rest. Now. |
Plus a trend arrow so you can see which direction things are moving — building fitness, recovering from fatigue, holding steady.
You're FRESH and your fitness is building. Let's use it — I'm suggesting a tempo run tomorrow.
You're BUILDING and fatigue is rising. Easy jog or rest day. Trust me on this one.
Flotti never says “your TSB is -16.4.” It says you’re tired and tells you what to do about it.
Why we hide the numbers
It’s not because the numbers are wrong. They’re great. But showing someone “TSB: -16.4” creates two problems:
- It’s meaningless without context. Is -16 bad? Depends on your fitness, your history, your goals. A zone label gives you the answer directly.
- It creates false precision. The difference between -16.4 and -15.8 is noise. What matters is the zone you’re in and the direction you’re heading.
If you want the raw values, Flott has a coach mode that shows CTL, ATL, and TSB with full precision. We're not hiding anything — we're just not leading with it. Better to talk about Fitness, Fatigue, and Form first, and save the acronyms for when you're ready.
The stuff the numbers miss
Even the best training metrics don’t capture everything. They don’t know:
- You slept terribly last night
- Work has been brutal this week
- You skipped lunch and ran on empty
- You’re nursing a sore achilles you haven’t mentioned
A FRESH status means nothing if you slept four hours. That's why Flotti combines your form zone with wellness data — sleep, resting heart rate, HRV — to build a fuller picture before making recommendations.
CTL, ATL, TSB — they're powerful metrics with terrible names. Flott translates them into Fitness, Fatigue, and Form so you can make better training decisions without a sports science degree. And when you're ready to go deeper, the raw numbers are one toggle away.
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