How Well Do You Hold Power Under Fatigue?

Track your performance decay with the Durability Score

This two-step test reveals how resilient you really are—by comparing your fresh 12-minute effort to one performed after a structured fatigue load.

What Is the Durability Score?

The Durability Score is one number: the percentage of your fresh 12-minute power you can still produce when fatigued.

Cadence and heart-rate changes are reported for context, but the score itself comes solely from power.

In other words, it tells you exactly how much of your wattage you keep when it really counts—late in a race, on a long training day, or during back-to-back rides.

Why It Matters

Most training only shows how fit you are when fresh.This test shows how well you perform when it actually matters—after you’ve already spent 1,000 kJ of effort.

Your Durability Score reveals:
Your true fatigue resistance
‍Whether you’re training the wrong system
How much work you can really hold, late in the ride

How It Works – The 2-Step Test

Step 1 – Fresh Baseline
Perform the structured Day 1 test
Record:
Average power (W)
Average heart rate (bpm)
Average cadence (rpm)

Step 2 – Fatigue Protocol + Repeat Test
Perform the structured Day 2 Test
Then repeat the same 12-minute effort.
Record the same metrics.
‍
→ Then input both sets into the Durability Score Calculator.

Take the Test. Track the Drop. Train the Fix.

→ [Start Step 1 – Fresh Test Input]
Download test files below
‍You’ll be guided through each phase. No guesswork.
Then return after your fatigue test to complete Step 2 and get your Durability Score.

Step 1

Durability Score – Step 1: Fresh Test

Durability Score – Step 1: Fresh Test

Enter your fresh 12-minute test data. This will be used to calculate targets for your Step 2 fatigued test.

Step 2

Durability Score – Step 2: Fatigued Test

Enter both Step-1 fresh and Step-2 fatigued 12-minute averages.

Get Your Free Athlete Durability Guide + Test

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