Marathon Swimming Nutrition: Art vs. Science

First, a Michael Pollan-inspired minimalist manifesto:

  1. Drink some carbs.
  2. Not too much.
  3. Some carbs are better than others.

One of the most daunting and mysterious aspects of preparing for a marathon swim is planning a nutrition strategy. And for good reason: Nutrition can make or break a marathon swim.

So, aspiring marathon swimmers often seek advice from their more experienced brethren. But how to sort through conflicting information and opinions?

The textbooks aren’t much better:

Here’s the thing: In planning your nutrition strategy, you must distinguish the art from the science - the “best practices” from the “special sauce.” Think for yourself. Pay attention to best practices, but don’t eat bagels and peanut butter just because Lynne Cox did.

What are the best practices? Here’s a good start:

Drink some carbs. Your gut processes liquid food faster than solid food.

Not too much. The goal isn’t to replace everything you burn There’s a limit to how much your body can process at once. A basic hour’s portion of Maxim (or equivalent) provides 58g of carbohydrates, 233 calories, and 750ml fluids (a 7.7% solution). Exceed that only with caution and care.

Some carbs are better than others. Maltodextrin is better than simple sugars* (e.g., sucrose, dextrose, and high-fructose corn syrup). Maltodextrin is the typical carbohydrate source in high-end, “designer” endurance fuels such as products by Hammer, First Endurance, and Infinit (and of course, Maxim and Carbo-Pro).

Simple sugars are the typical carbohydrate source in lower-end, mass-production sports drinks such as Gatorade, Powerade, and Vitamin Water.

Basically, if you can buy it at a gas station, don’t use it on a marathon swim.

And… that’s it. All the other stuff - protein, amino acids, electrolytes - you don’t actually need them (and in some cases you don’t want them). Under certain circumstances, they may help at the margin; but there are risks. Supplemental protein and electrolytes have probably harmed _more marathon swims than they have helped. The main thing is to consume carbohydrates - in a _form and amount your body can easily digest while swimming. Everything else is just “special sauce.”

Regarding the last point: Why is maltodextrin better than simple sugars? To answer this question, I’ve recruited a special guest author. Stay tuned for the next post…

* Note: I am aware of Peter Attia’s argument that SuperStarch is superior to maltodextrin. That may be true - but I haven’t tried it. I would simply note that Dr. Attia agrees that maltodextrin is superior to simple sugars.

Posted 22 January 2012 in: knowledge base Tags: nutrition

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