Free Running Tool

Aerobic Decoupling Calculator

Measure aerobic fade on long runs. Calculate your Pa:HR ratio and endurance efficiency score. Free tool with Strava import.

Features

  • Calculate Pa:HR decoupling percentage
  • Analyze pace vs heart rate drift over time
  • Import long runs from Strava automatically
  • Get your Aerobic Efficiency Score
  • Track aerobic development over months

How It Works

Aerobic decoupling measures how well your heart rate stays stable relative to pace during a long run. We compare the first and second halves of your run: (HR2/Pace2) vs (HR1/Pace1). Under 5% decoupling indicates excellent aerobic fitness; over 10% suggests more base training is needed.

Benefits

  • Objectively measure aerobic fitness progress
  • Know when you're ready for harder training
  • Identify if you're running easy runs too hard
  • Monitor recovery and fatigue

Frequently Asked Questions

What is good aerobic decoupling?

Under 5% is excellent and indicates strong aerobic fitness. 5-10% is moderate, over 10% suggests more aerobic base work.

Which runs should I analyze?

Use steady-state runs of 60+ minutes at easy pace. Hilly runs or runs with surges won't give accurate readings.

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