The Physiology of Endurance Running Podcast The Science of Trail & Ultra Running - with Dr Simon de Waal
Mar 12, 2026
Dr Simon de Waal, a senior lecturer and researcher on trail and ultra running physiology, discusses why trail athletes need different lab tests. He talks about uphill-specific testing, how steep gradients change running mechanics, and practical outdoor testing and training tips. The conversation also covers pacing on technical courses and plans for studying resilience and durability in long-distance runners.
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How Jana's Half Marathon Got Simon Into Trail Research
- Simon re-entered running after his wife Jana trained for a half marathon and they ran trails around Cape Town and Stellenbosch.
- That personal trail experience shaped his PhD focus from physiological curiosity to applied trail research.
Classic Endurance Model Is Weaker For Trail Running
- The classic endurance model (VO2max, lactate threshold, running economy) explains much less of trail performance than road events.
- Simon's systematic review found those markers accounted for ~50% of variance in short trail races and almost no ultra-specific evidence existed then.
Uphill Sections Drive Trail Race Outcomes
- Pace analysis of a 100km trail race showed uphill segments correlate far more with overall race time than level or downhill sections.
- Runners spend more time and metabolic cost on uphill work, making uphill economy especially predictive of outcome.