Join Coach Scott Johnston for a conversation with Paul Booth, who works alongside Scott as a Performance Nutritionist on the teams of 2025 UTMB 1st-place finishers Tom Evans and Ruth Croft. In this discussion, they explore how metabolic processes are measured in the lab, and look at the latest research on carbohydrate fueling and fat utilization in ultra runners. See episode guide for topics covered. 

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Episode Guide

00:00:00 Introduction

00:01:27 Can metabolism be measured through calorimetry?

00:04:31 Are VO2 Max tests capable of measuring metabolic equilibrium?

00:10:57 Applying lab derived energy usage to variable terrain

00:16:58 Recent study of carbohydrate utilization in ultra running

00:31:34 Does carbohydrate introduction shift substrate utilization?

00:33:22 Is high carbohydrate intake inhibiting fat utilization?

00:42:43 Fat utilization vs. carbs during races

00:46:01 Does high carbohydrate intake cause carbohydrate dependence?

00:53:32 Pitfalls of reliance on widely available metabolic testing machines

01:03:27 Tips for feeding between and during runs

01:16:16 Final thoughts