Original episode & show notes | Raw transcript
Commercially available sports drinks have demonstrated significant success in hydrating athletes. Their effectiveness stems from a scientific understanding of human physiology during exercise. By analyzing the core components of these products, we can “reverse-engineer” a homemade hydration solution. This approach offers two distinct advantages:
Economic Viability: Creating a mix from bulk ingredients is significantly more cost-effective for athletes who consume large volumes.
Customization: A homemade formula allows for precise adjustment of ingredients to meet an individual’s specific physiological needs, taste preferences, and the demands of varying environmental conditions.
This guide will break down the science of sweat, the function of each ingredient in a hydration mix, and the principles for customizing a formula to your unique requirements.
During exercise, the body sweats to regulate its core temperature. This process involves the loss of both water and essential minerals known as electrolytes. Effective hydration strategy aims to replace both of these components.
Water Loss: Dehydration thickens the blood, which increases cardiovascular strain, reduces the efficiency of oxygen delivery to working muscles, and impairs cognitive function, all of which degrade athletic performance.
Electrolyte Loss: Electrolytes are critical for maintaining fluid balance, nerve function, and muscle contraction. Failing to replace them can lead to cramping, hyponatremia (a dangerous condition of low blood sodium), and impaired performance.
While sweat composition varies genetically and with heat acclimatization, it primarily consists of the following electrolytes:
Sodium (Na+): This is the most abundant electrolyte lost in sweat. Most individuals lose between 0.5 to 1.5 grams of sodium per liter of sweat. It is the highest priority for replacement as it plays a central role in fluid retention and muscle function.
Chloride (Cl-): The second most abundant electrolyte. It is typically consumed with sodium in the form of sodium chloride (table salt).
Potassium (K+), Calcium (Ca2+), and Magnesium (Mg2+): These are lost in much smaller quantities. For instance, calcium loss is only about 50-100 milligrams per liter of sweat. While important for overall health, their replacement during exercise is a lower priority than sodium.
A Note on Coconut Water: While often marketed as a natural sports drink, coconut water is very high in potassium but low in sodium. It is therefore not an effective primary hydration source during intense exercise where sodium loss is the main concern.
An effective hydration drink is built on a foundation of water, specific carbohydrates, and a carefully selected profile of electrolytes.
The primary role of sugar in a hydration drink is not just to provide energy, but to facilitate the rapid absorption of water and electrolytes from the small intestine into the bloodstream. This occurs through a process called co-transport.
Dextrose (Glucose) and Sucrose: The gut has different protein transporters for different types of sugars.
SGLT1 (Sodium-Glucose Linked Transporter 1): This transporter moves glucose (dextrose) from the intestine into the cells. Crucially, it must bind to sodium to do so, effectively pulling sodium along with it.
GLUT5: This transporter moves fructose (a component of sucrose) into the cells.
The Multi-Carbohydrate Advantage: By using both dextrose and sucrose (which is composed of glucose and fructose), the formula utilizes multiple transport pathways simultaneously. This increases the rate at which sugar, and by extension sodium and water, can be absorbed, a phenomenon known as “letting water piggyback on our absorption of sugars.”
Sodium Citrate: This is the preferred source of sodium in a liquid solution for exercise.
Palatability: Unlike sodium chloride (table salt), which can be harsh and unpalatable in a drink during intense exercise, sodium citrate has a milder, slightly tart flavor that is much more agreeable.
Function: It serves as the primary ingredient for replacing sodium losses and is the key variable for customization based on individual sweat rates.
Calcium Lactate & Potassium Citrate: These salts replace the secondary electrolytes lost in sweat. While they can be considered optional, including them provides a more complete electrolyte profile. Calcium lactate is a stable and easily absorbed form of calcium.
Chloride Replacement Strategy: Since sodium citrate is used instead of sodium chloride, chloride must be replaced through other means. Consuming regular foods, such as boiled potatoes sprinkled with table salt, is an effective and palatable strategy for this.
Citric Acid: Many athletes find acidic flavors (lemon, lime, orange) more refreshing and palatable during heavy exertion. Citric acid provides this tartness. It is potent, so it should be added cautiously and adjusted to taste.
Ascorbic Acid (Vitamin C): This contributes to the overall flavor profile, often imparting a “dryness” to the drink, similar to that found in some commercial orange-flavored mixes. Its inclusion is purely for taste preference.
Freeze-Dried Fruit: This is an excellent natural source of flavor and color. Grinding it into a powder allows it to be easily mixed. It should be processed while cold to prevent it from gumming up a food processor and can be stored at room temperature.
The concentration of a sports drink, known as its osmolality, is a critical factor for rapid absorption.
The 4-5% Solution Rule: The goal is to create a solution that is hypotonic or isotonic relative to the blood. This means its total concentration of solutes (sugars and salts) is slightly less than or equal to that of blood plasma. A solution that is too concentrated (hypertonic) will draw water into the intestines to dilute it, delaying absorption and potentially causing gastrointestinal distress.
Calculation: The target is approximately 4 to 5 grams of total solutes per 100 milliliters of water. A standard serving of the recipe discussed in the podcast, when mixed in 500 mL (a standard small bottle), will achieve this optimal concentration.
This is where a homemade formula truly shines. The base recipe can be adjusted based on three key factors:
Identifying a “Salty Sweater”: You are likely a high-salt sweater if you experience the following:
White, salty residue (caking) on your skin or clothing after exercise.
Sweat that stings your eyes.
A craving for salty foods during or after long rides.
Modification: If you identify as a salty sweater, the primary adjustment is to increase the amount of sodium citrate in your mix. Some athletes may find that nearly doubling the baseline amount works best for them, improving both performance and palatability.
Acidity: If you prefer a more tart drink, gradually increase the amount of citric acid.
“Dryness”: If you enjoy a dry finish, add or increase the amount of ascorbic acid. If you dislike it, omit it completely.
Flavor Intensity: Adjust the amount of freeze-dried fruit powder to achieve your desired flavor strength.
Ingredient Sourcing: Ingredients can be sourced from specialty food suppliers (the podcast mentions Modernist Pantry as an example, though without affiliation).
Anti-Doping Warning (WADA): For competitive athletes subject to testing, it is imperative to source ingredients from a reputable supplier that has been certified by organizations like NSF International. This ensures the ingredients are tested and free from any substances banned by the World Anti-Doping Agency (WADA). Using unverified sources carries a risk of contamination.