Marathon Swimming Nutrition – Index of Articles

Marathon Swimming Nutrition – Index of Articles

I’ve written a variety of posts over the last few years on nutritional considerations in marathon swimming. Here they are in one place for your reference.


Series: The Art & Science of Marathon Swimming Nutrition

On Recovery Drinks - includes a DIY powdered recovery drink recipe

On Maltodextrin - Maxim vs. Carbo Pro

Series: On Nutritional Science in Marathon Swimming

On Peter Attia’s nutrition webinar

Marathon swimming and low-carbohydrate diets

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Marathon Swimming Nutrition: Do it yourself

Marathon Swimming Nutrition: Do it yourself

The last in a series of four posts about nutrition in marathon swimming. To recap:

  • Marathon swimming nutrition is both art and science. There are both “best practices” (generalizable to many) and “special sauce” (generalizable to few). In general, a nutrition plan that aims to drink some carbs — not too much is a good place to start.
  • Some carbohydrates are “better” than others, due to differences in osmolality. An endurance athlete can consume more carbohydrate in the form of maltodextrin, compared to simple sugars, without overwhelming the digestive system. Also, maltodextrin is neutral in taste, thus providing more control over your drink’s flavor.
  • Of the many designer endurance fuels on the market, few are ideal for marathon swimming. High electrolyte content makes sense for runners, cyclists, and triathletes – but less sense for swimmers (even less sense for ocean swimmers).

Although I do think Perpetuem is a good product for swimmers, my best advice is to skip the one-size-fits all formulas and do it yourself. This is the only way to ensure you get the nutrition you need on a marathon swim, and not the stuff you don’t need.…

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Marathon Swimming Nutrition: A product comparison

Marathon Swimming Nutrition: A product comparison

I hope you’ve enjoyed “Nutrition Week” here at Freshwater Swimmer. As you may have noticed, I’ve been vague about recommending specific products. There’s a reason for that: I don’t believe there’s any single best nutrition plan for all people, in all situations. However, I’ve personally tried a number of sports drink products, and will share my thoughts on them.

Beginning with the low-end market… These products include, but are not limited to: Gatorade, Powerade, and Vitamin Water. Some signs you might be buying one of these products:

  • You can buy it in supermarkets and gas stations
  • It is brightly colored
  • Produced by a subsidiary of a Fortune 500 company, such as Coca-Cola or PepsiCo
  • Advertised on national television and/or billboards
  • Has a flashy, Javascript-heavy website that contains very little actual information.
  • Ingredients lists may be difficult to find. When you do find one, it’s often extensive and includes strange additives like “xanthan gum” and “brominated vegetable oil.”
  • Most relevant to endurance athletes: The primary carbohydrate source is a simple sugar such as sucrose, dextrose, or high-fructose corn syrup (or a combination).


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Marathon Swimming Nutrition: Osmolality and why it matters

Marathon Swimming Nutrition: Osmolality and why it matters

On a sunny late morning in Chicago last summer, I told Ted Erikson about the nutrition plan I’d recently used for Tampa and MIMS. Ted EriksonMy plan called for an hourly cycle of two Maxim feeds and one Perpetuem feed. Ted sort of chuckled, and then said something I’ll never forget: “You know, Evan… all you really need is glucose.”

And he’s right: Glucose is the basic unit of energy. Whether you feed on Gatorade or Maxim, it all ends up as glucose anyway. I mention this story because it’s worth remembering as you read what follows. When I said in the previous post that “some carbs are better than others,” I don’t mean that maltodextrin is the be-all-end-all, magical elixir of marathon swimming. It’s not. Many swimmers – including some of the best – have used “simple sugars” to fuel a marathon swim. You can, too!

However, it’s my view (based on both research and experience) that the basic recommendation to an aspiring marathon swimmer – in the absence of strong preferences otherwise – should be a maltodextrin-based fuel. 

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Marathon Swimming Nutrition: Art vs. Science

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:

  • In Dover Solo, Marcia Cleveland recommends “warm, energy-providing liquids, followed possibly by some solid food, or energy gel.”
  • Steven Munatones’ book suggests to “try everything within reason: energy drinks, bananas, sliced peaches, chocolate, and cookies.” He also wisely notes that “what works for another swimmer may not necessarily work for you.”
  • Penny Lee Dean devotes a section to nutrition in her book, but in 2012 her recommendations are a bit dated.


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Marathon swimming and low-carbohydrate diets

Marathon swimming and low-carbohydrate diets

Following up my previous post on channel swimmer/physician Peter Attia’s webinar about “Nutrition for Open Water Swimming”…

Peter Attia

As you may have heard, the topic of the webinar (and subsequent video interviews with Open Water Source) was broader than the title indicates. In marathon swimming, “nutrition” typically refers to the stuff consumed during a swim to provide energy. But Dr. Attia was more interested in what people eat when they’re not swimming – i.e., diet.

If I could summarize his point, it would be this: Endurance athletes are asking the wrong question. Sure, Maxim is probably better than Gatorade during a swim. But the more important issue is: How best to train our metabolism through diet so it will most efficiently convert fuel into energy. According to Peter (who now has a blog), the ideal solution is a ketogenic diet.

The ketogenic diet is a type of low-carbohydrate diet that restricts carb intake so severely (less than 60 grams per day – equivalent to a small-ish bowl of pasta) that the body is forced to burn fat for energy instead of the “easy” glucose offered by carbohydrates.…

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On Peter Attia’s nutrition webinar

On Peter Attia’s nutrition webinar

Yesterday Open Water Source hosted a fascinating web-presentation by Peter Attia, a physician and Catalina Channel solo swimmer. The topic: Nutrition for Open-Water Swimming. Right up my alley, to say the least! There’s good news and bad news.

Bad news first: The webinar was oversubscribed so, despite pre-registering a week ahead of time, I got locked out. The good news: I was able to obtain the audio and slides, and “listen in” after the fact. (Friendly suggestion to the good folks at Open Water Source: Please don’t overbook your webinars. I realize they’re free, but still…)

The even-better news: The webinar was excellent. Though, somewhat different than I expected. A few weeks ago a friend sent me a whitepaper authored by Dr. Attia, entitled “Swimming in the Intensive Care Unit.” The gist of the paper is that a marathon swim is enormously stressful on the body, producing physiological symptoms not unlike those of a patient in the ICU with a traumatic injury. Therefore, proper nutrition is critically important to the success of such an endeavor.…

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Calories burned vs. calories consumed

Calories burned vs. calories consumed

How many calories should you consume in a marathon swim?

According to an article on the ”Nutrition Demands of Open Water Endurance Swimming,” swimming burns 2.93 calories per mile, per pound. The author, Don Macdonald, did the math and figured that he burns approximately 15,000 calories during a 24-mile swim. Later in the article, Macdonald goes on to say:

As you can imagine, it is difficult to eat 15,000 calories over a 13-hour period without training the stomach to handle this input.

Leaving aside the reasons (discussed previously) that the above formula is probably bogus, let’s think about this: eating 15,000 calories in 13 hours. That’s 1,154 calories per hour. Burning this many calories is one thing. You might be able to do it for an hour; probably not for 13 hours straight. But consuming that many calories is something else entirely.

Can you guess what would happen if you tried to consume 15,000 calories during a 24-mile swim? That’s right – you’d get sick and would not finish the swim. It’s not a matter of – as Don Macdonald says – “training the stomach to handle this input.” Nobody can train their stomach to process 1,150 calories/hour for 13 hours, while simultaneously swimming 24 miles.…

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Swim efficiency and energy consumption

Swim efficiency and energy consumption

In the last post I bemoaned the lack of credible science about marathon swimming. One is reminded of the William Goldman quote about the movie industry: Nobody knows anything.

Here’s a good example. A few days ago a Facebook friend linked to an intriguing-looking article. Published on a science-y looking website (“Your one-stop resource for longevity, health, exercise, nutrition, and scientific articles all to help you live a longer, fuller life”), the article is authored by marathon swimmer Don Macdonald.

One section seemed of particular interest: “Nutritional Demands of Open Water Endurance Swimming.” An excerpt:

Nutritional endurance demands biochemical changes of your body. The basic calculation for the amount of calories burned while swimming is 2.93 calories per mile, per pound. I weigh 207 pounds, and therefore burn 14,556 calories in a 24-mile swim, (2.93 calories x 24 miles x 207 pounds = 14,556 calories). You must also add 10-15 percent of your burnt calorie total for the energy it takes your body to keep itself warm. In this case, adding another 1,500 calories.



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On science in marathon swimming

On science in marathon swimming

In marathon swimming, there’s very little in the way of credible science – that is, methodologically rigorous, experimentally controlled, peer-reviewed science. It’s not hard to understand why: Open-water swimming, especially the marathon variety, is a tiny market compared to land-based endurance sports. Market size is related to the potential for making money, and the potential for making money is, in turn, related to funding and motivation for scientific research. Even in triathlon (an enormous, lucrative market), swimming is often seen merely as a warm-up to the bike and run, so there’s little effort to understand it.

As a result, marathon swimmers are left with approximately four strategies for acquiring knowledge about their sport – specifically, the physiological demands of long-distance swimming, and the nutrition required to fulfill those demands:

  1. Figuring out what is known, scientifically, about land-based endurance activities, and applying it to swimming.
  2. Figuring out what is known, scientifically, about pool swimming (in which races last anywhere between 20 seconds and 15 minutes), and applying it to marathon swimming (in which a race or solo event may last 10 or 15 hours).


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