Science
In part three of his series on cyclists’ hydration needs, Dr. Alan McCubin is divided into the world of electrolytes to organize facts from fiction.
How much of the sodium you lose from sweat needs to be replaced? And why?
Cristoflamone
In 2016, I was fortunate to step into a blank doctoral program. I literally managed to choose the topic I wanted to study. After thinking hard for about three seconds, I decided to study sodium replacement in endurance athletes. I had no strong passion for this topic, but my motivation was clear. Of the three main things you use or lose during exercise, there were already very specific guidelines for carbohydrates, hydration and hydration. These guidelines were not perfect and yet not perfect, but they are the starting point. But when it comes to electrolytes in general, or sodium specifically, there was nothing else than literally “If you lose a lot, you should consider replacing some of it.”
This reflects the lack of research available at that time, rather than criticism of those writing such guidelines.
Without official advice or guidelines for athletes’ electrolyte exchange, something inevitably ended up filling the vacuum of knowledge. The athletes were already measuring their sweat sodium loss, so someone had to tell these athletes what they would do with the outcome. But the advice was never based on science. Instead, it could have been a mixture of guesswork, personal opinions, and marketing-driven messages designed to promote the use of electrolyte products.
What is an electrolyte?
From a pure chemistry perspective, an electrolyte is a material that conducts an electric current through ion movement (positive and negatively charged particles). A Google search for electrolytes gives references to human physiology and battery technology.
In humans, these electrolytes are mostly minerals, often (but not always) found in food as salts (sodium chloride or table salts), and when dissolved in water, they are divided into individual ions. The main things we think about are sodium chloride, chloride, potassium, magnesium, calcium, phosphates, and bicarbonates. These electrolytes have a variety of roles, from minerals (mainly calcium and phosphates) that provide minerals that give bone structural stiffness (mainly calcium and phosphates), changes in the body’s acid-base balance (bicarbonate), and changes from nerves and nerves to nerves to muscle (multiple electrifications).
They also have other roles within the body, but the larger ones control the amount and movement of water throughout the body. Sodium and chloride are the major extracellular players: potassium, phosphate and magnesium within the cell.
Which electrolyte is important for athletes?
Athletes tend to focus on electrolyte replacement in the context of sweat loss during exercise. Looking at the typical electrolyte composition of sweat, two electrolytes dominate – sodium and chloride. This is because sweat is formed from the stromal fluid surrounding the cells of the sweat glands, so here there are mountains of sodium and sodium chloride, with few other electrolytes. At the time, our sweat glands have a mechanism to regain some of the sodium and chloride, but there are no other electrolytes.
Therefore, while other electrolytes are still important for health (and from the perspective of pure loss and replacement during exercise, it is possible that in some people’s daily diets, things like calcium and magnesium are significantly lacking in some people’s daily diets). They are primarily gathered in food, and our bodies mostly regulate losses through the urine together, so we need to worry about sodium as chloride tagged for rides.
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