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:
- Figuring out what is known, scientifically, about land-based endurance activities, and applying it to swimming.
- 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).
- Word of mouth - finding out what works for other marathon swimmers. This is how most people discover Maxim - because that’s what they use in the English Channel.
- Individual trial-and-error. Penny Palfrey likes watered-down porridge and chocolate ice cream. Who knew?
Most successful marathon swimmers use each of these strategies at some point. The problem with the hybrid approach, however, is that it neglects one very important thing: actual, science-based knowledge about marathon swimming. As science has continually shown since at least Galileo, there’s a lot we don’t know - and much of what we think we know might actually be totally false.
A few questions, off the top of my head:
- How are nutritional needs affected by the environment in which the activity occurs? E.g., how is running a marathon in 60-degree air different from swimming a marathon in 60-degree water?
- By corollary, are products designed for land-based endurance activities sub-optimal for water-based endurance activities?
- Is digestion during an endurance event affected by physical orientation? E.g., swimming horizontally vs. running vertically?
- How does electrolyte loss differ between running and swimming? Are supplemental electrolytes necessary while swimming in a saltwater (i.e., electrolyte-rich) environment?
- How should fluid consumption be adjusted for cold-water swims vs. warm-water swims?