A practical framework for fueling that explores the history and science of race nutrition to help you understand the products on the shelf, turning confusion into confidence.

It starts with a wall of brightly colored gels and drink mixes, each promising endurance in a pouch. Runners swear by their favorites, but few can explain why they work—or don’t. Matt and Molly pull back the curtain on the science and history behind those packets, turning a maze of sugar ratios, salt counts, and gut grumbles into something you can actually understand. They examine why some products seem to love you while others ruin your race, practically breaking down the make up of different products out there, and what the science actually says about how our bodies use all this stuff.

Episode Description:

In this episode of Legwork, Matt and Molly take on one of running’s most confusing topics: fueling. They trace how we went from ancient “performance foods” to modern gels and drink mixes, and why understanding what’s inside those packets can make all the difference.

Together, they cover:

• How fueling evolved from ancient rituals to modern sports science

• The difference between energy systems — carbs, fats, and how the body actually uses them

• What “isotonic,” “hypertonic,” and “2:1 ratios” really mean, and how those formulas affect absorption and gut comfort

• Why some products upset your stomach while others don’t

• How to approach carb loading and in-race fueling more strategically

• The myths and mistakes that keep runners underfueled

• And how to navigate the wall of options on the shelf with more confidence

Along the way, they share personal fueling mishaps (including Matt’s maple syrup era), laugh through gut science, and translate complex research into clear, practical insight.

Whether you’re training for your first half marathon or trying to shave minutes off a PR, this episode will help you understand what your body needs — and fuel smarter for whatever’s next.

Fuel Selector Google Sheet: https://docs.google.com/spreadsheets/d/1u7Rh8LWrgB_9B3kKKpKMwTEnqXyRcc0js1UYw4vwTCg/edit?usp=sharing

Chapter List:

00:00 Introduction, Matt's Fueling Eras, and Why This Episode Matters

09:08 Agenda for the Episode

10:00 Historical Perspectives on Nutrition and Performance

16:09 The Evolution of Sports Training and Nutrition

20:06 Understanding Energy Systems: Carbs

29:22 Understanding Energy Systems: Fats

40:15 The Impact of Carbohydrates on Performance

47:07 Understanding How Nutrition Products Incorporate What We Know Of These Energy Systems Into Their Formulas

49:27 Understanding Sugar Ratios in Sports Nutrition

55:21 Isotonic vs Hypertonic Fuels: What You Need to Know

01:04:49 Carbohydrate Requirements for Endurance Events

01:13:17 The Importance of Carb Loading Before Races

01:28:03 Troubleshooting Nutrition Issues During Races

References:

1. Currell K, Jeukendrup AE. Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sports Exerc. 2008 Feb;40(2):275-81. doi: 10.1249/mss.0b013e31815adf19. PMID: 18202575.

2. Sedlock DA. The latest on carbohydrate loading: a practical approach. Curr Sports Med Rep. 2008 Jul-Aug;7(4):209-13. doi: 10.1249/JSR.0b013e31817ef9cb. PMID: 18607222.

3. Arnall, D.A., A.G. Nelson, J. Quigley, et al. Supercompensated glycogen loads persist 5 days in resting trained cyclists. Eur. J. Appl. Physiol. 99:251Y256, 2007.

4. Jeukendrup, A.E. Training the Gut for Athletes. Sports Med 47 (Suppl 1), 101–110 (2017). https://doi.org/10.1007/s40279-017-0690-6

5. W Larry Kenney,Jack H Wilmore,David L Costill. Physiology of Sport and Exercise 8th Edition s