Why Trail Running Breaks the Rules of Exercise Science with Dr. Simon de Waal

In road running, VO2max, lactate threshold, and running economy can explain up to 95% of the variation in performance between athletes. In trail running, that same model barely holds together, with running economy being the worst predictor of the three. In this episode, Dr. Simon de Waal walks through his research journey trying to work out why. From his systematic review of the existing evidence, to a full pacing analysis of Ultra Trail Cape Town using Strava data and treadmill testing at steep gradients. Along the way we cover velocity at VO2 max as a hidden composite metric, why uphill-specific testing changes the picture, why downhill collapse is the clearest sign of mechanical fatigue late in a race, and why prior race results still beat most lab tests. It's a comprehensive look at just how multifactorial trail performance really is, and why researchers are still working out how to measure it properly. Dr Simon de Waal grew up running trails around Cape Town before turning it into a research career. He completed his PhD at Stellenbosch University under cycling physiologist Robert Lambert, and now researches trail running performance at the University of Gloucestershire while coaching through Rooted in Dirt. Looking for coaching or guidance? Read more at https://bornonthetrail.substack.com/p... RELATED BORN ON THE TRAIL CONTENT Your Watch Doesn't Understand Trail Running Performance: https://bornonthetrail.substack.com/p... Analysing the Limiters of Ultra Marathon Performance: https://bornonthetrail.substack.com/p... How To Improve Your Performance by 44% in Just 10 Weeks*: https://bornonthetrail.substack.com/p... Why Do Ultra Endurance Athletes Get Better With Age?: https://bornonthetrail.substack.com/p... The Overlooked Aspects of Ultramarathon Training: https://bornonthetrail.substack.com/p... FOLLOW DR. SIMON DE WAAL Work with Dr. de Waal at https://www.glos.ac.uk/staff/profile/... or by contacting him at [email protected] Looking to get coached by Dr. de Waal? Find him at https://rootedindirt.com/ and   / rootedindirt   WATCH THIS SHOW ON OTHER PLATFORMS Substack: https://bornonthetrail.substack.com/p... YouTube:    / @bornonthetrail   Spotify: https://open.spotify.com/show/6o5yHth... Apple Podcasts: https://podcasts.apple.com/us/podcast... YouTube Music:    • Born on the Trail: Going Longer   FOLLOW BORN ON THE TRAIL ON SOCIAL MEDIA Substack: https://bornonthetrail.substack.com/ Instagram:   / bornonthetrail   TikTok:   / bornonthetrail   Facebook:   / bornonthetrail   CHAPTERS ----------------------------- 00:00 Intro 07:40 Trail Culture vs Football/Soccer Culture 11:15 Why Running Economy is a Bad Metric for Trail 19:09 Why A Good Trail Runner Has a High Velocity at VO2 Max 24:32 Does The Test Protocol Influence Your VO2 Max? 27:36 Why Durability Could be the Missing Piece 43:33 Physiological vs Mechanical Resilience 46:17 How Valuable are Trail-Specific Field Tests? 1:00:30 Pacing Strategies and Correlations from Ultra Trail Cape Town 1:09:24 Why Going Downhill Too Fast Can Kill Your Race 1:13:48 A Better Lab Protocol for Trail 1:21:49 Future Research and Outro