The history of endurance fueling

University of Florida researchers created the first purpose-built sports drink — a simple solution of sugar, salt, and water designed to combat heat exhaustion in football players. This basic formula dominated for over 30 years.

Researchers discovered that the SGLT1 transporter — the only gateway for glucose into the bloodstream from the gut — has a hard physical saturation limit. No matter how much glucose you consumed, your body could only absorb approximately 60 grams per hour.

The discovery that fructose uses an entirely independent transporter (GLUT5) shattered the 60g ceiling. By combining glucose and fructose, athletes could absorb 50% more carbohydrate per hour than glucose alone — without the GI distress.

Research proved that it's caloric density — not osmolality alone — that controls how fast your stomach empties. Solutions above 8-10% carbohydrate concentration sit in the stomach, starving working muscles of both fuel and fluid.

A landmark crossover study proved that a 1:0.8 glucose-to-fructose ratio was significantly superior to the classic 2:1. Oxidation efficiency jumped from 62% to 74%, power output increased ~3%, and reports of stomach fullness and nausea were dramatically reduced.

Two technologies emerged targeting the gastric emptying bottleneck: Maurten's alginate hydrogel (proposed to encapsulate carbs in the stomach, though independent evidence for a performance benefit is weak) and Cluster Dextrin (ultra-low osmolality via a branched cyclic molecular structure).

The modern approach separates fuel from hydration, scales sodium independently based on conditions, and recognizes a powerful truth: bulk maltodextrin + fructose + salt achieves the same physiology as premium products at a fraction of the cost.