What is Threshold Power?
Running power provides numbers that represent your effort – your running intensity.
At lower intensity levels, your body achieves a metabolic steady(ish) state and you can sustain your effort for an extended period. Researchers call these domains ‘moderate to heavy.’
At higher intensity levels, you can’t achieve a metabolic steady(ish) state. You’ll fatigue much more rapidly and need to slow down or stop. Researchers call these ‘severe to extreme’ domains.
The change from heavy to severe doesn’t happen at a precise point – it’s a ‘phase transition’ over a narrow range of intensities, with lots of metabolic changes occurring at different rates and in parallel.
There are many names for this phase transition – Anaerobic Threshold, LT2, VT2, Critical Power and more.
Threshold Power
Threshold Power is an intensity that’s within (or close to) the phase transition from heavy to severe.
It’s a foundation metric – one that’s used by many other power metrics.
Threshold Power:
✅ is highly correlated with speed in endurance events – from 5k through marathon and beyond
✅ can be identified using field-based tests – no need for lab-based testing
✅ can be improved with training – improve your threshold, and you’ll improve your performance
✅ is an important representation of your running fitness – you should track it as part of your training
For more information on intensity domains and the phase transition, see Burnley, M., (2020) Exercise intensity domains and phase transitions: the power-duration relationship
Topic: Threshold Power
⏩ How do I find my threshold power?
⏩ How do I use threshold power?