Paul Booth: New Science On Carbohydrate Utilization In Ultra Running

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. 

To submit your own training questions, or if you would like to learn more about the Evoke Endurance community, visit our Reddit forum: https://www.reddit.com/r/evokeendurance/, or contact us here.

Watch

Listen

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