evokecast #15 Vault Classic: Metabolic Testing with Director of Sports Performance at UC Davis, Judd Van Sickle
Feb 16, 2023
Judd Van Sickle, Director of Sports Performance at UC Davis, discusses metabolic testing, fat adaptation, and aerobic deficiency. They explore topics such as maximizing fat utilization for endurance athletes, methods for metabolic testing and determining aerobic threshold, and the benefits of metabolic testing to reveal metabolic deficiencies.
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What Metabolic Efficiency Testing Actually Measures
- Metabolic efficiency testing measures how well your body uses fat versus carbohydrate using VO2 and VCO2 to compute fuel mix.
- The crossover (50% fat/50% carb) and fat max reveal at what intensity you shift fuels, informing individualized training zones.
Separate VO2max From Metabolic Efficiency Testing
- Do separate tests for VO2max and metabolic efficiency because VO2max protocols are short and non–steady-state, while fat-usage measures require longer steady stages or fasting.
- Running both in one session misrepresents fat oxidation and suppresses maximal performance if fasted.
Aerobic Threshold Is Not One Single Number
- Aerobic threshold can be defined multiple ways (gas exchange, ventilatory, lactate, economy, fat max) and they don't always align for an individual.
- For mountaineers and long events, fat max often better represents practical aerobic ability than gas exchange threshold.