In this second episode of The Physiology of Endurance Running Podcast, we explore all aspects of the 2nd threshold. We cover:

• What is the 2nd threshold and why is it important for performance


• What do we know about the determinants of the 2nd threshold


• Do we know how best to train it?


• How can we use the critical speed model to calculate our 2nd threshold outside of a lab and without lactate measurements


• How can we apply the critical speed model to our own training

Critical Speed Calculator

You can access the calculator via this link. You will need to download the Excel file in order to edit the document. Let me know if it doesn't work!

Key References



"The maximal metabolic steady state: redefining the ‘gold standard’"

"Muscle metabolic responses to exercise above and below the “critical power” assessed using 31P-MRS"

"Critical power is positively related to skeletal muscle capillarity and type I muscle fibres in endurance-training individuals"

Specialists you should follow

Dr Mark Burnley: Twitter Profile and YouTube channel

Dr Philip Skiba: Twitter Profile and Book

Find more from me on Twitter and Strava, while here is a link to my  "Physiology of Endurance Running"  webinar series.