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Methodology

How we write fueling protocols

Every calculator and guide on this site follows the same three-step process: literature, practitioner testing, and calibration against feedback from the runners Marcus coaches. We aim to be transparent about which parts of each recommendation are well-supported and which are practitioner judgment.

1. Literature

We start from peer-reviewed research and official sport-science guidance. The main sources we lean on:

  • American College of Sports Medicine joint position statement on nutrition and athletic performance (Thomas, Erdman & Burke, 2016)
  • International Society of Sports Nutrition position stands on protein, carbohydrate timing, and hydration
  • Jeukendrup's work on multiple transportable carbohydrates (2010 onward)
  • Burke's work on carb-periodisation and train-low research
  • Costa & colleagues' exercise-induced GI syndrome research for ultra-distance considerations
  • USATF coaching education reference materials

2. Practitioner testing

Before a calculator or protocol goes live, Marcus runs it with a handful of runners from his program across a 6–10 week block. For race-day calculators, that means runners test the plan in long runs and tune-up races, then report back on what worked and what failed. We adjust the protocol based on that feedback — especially for sodium and gel cadence, where individual variance is large.

3. Calibration

After publication, we track corrections we get by email. If the same pattern of feedback shows up three or more times (“this gel cadence is too aggressive for first-time marathoners” or similar), the protocol gets revised and the article carries a visible “Updated” date.

What we will not recommend

  • Fat-burner supplements, stimulants, or “race-day pills”. Not worth the risk, limited evidence, and banned-substance risk for anyone subject to USATF or WADA.
  • IV hydration for recreational runners. Oral fluids work. IV is for medical tents, not training.
  • Extreme ketogenic diets for marathon pace. Reasonable for some 100-milers. Actively harmful for fast marathon racing.
  • Any “cleanse” or detox product. No evidence, often contraindicated with training load.

Review cadence

Major articles are reviewed at least every 12 months and any time new evidence changes a protocol. The last-updated date on each article reflects the most recent review, not the original publication date.

Corrections

If you find an error, please email corrections@endurance-fueling.com. Substantive corrections are logged at the bottom of the affected article.