Hydration Dictionary

by | Nov 22, 2016

Dr. Stacy Sims, Ph.D., Environmental Exercise Physiologist, Nutrition Scientist and elite and pro endurance athlete understands from experience how nutrition and hydration affect performance. She is currently working with Nuun and Co. on hydration education, product innovation and clean living initiatives. She has helped popularize a new approach to exercise hydration, with a focus on low-calorie electrolyte drinks that are more easily absorbed than sugary exercise drinks. Through her latest research in the fields of exercise science and natural foods, Sims defines the hydration terms you need to know to fuel your body.

Osmolality — The concentration of all chemical particles found in the fluid portion of the blood. Normal human blood osmolality sits at 280 to 290 mOsmol. This measure indicates the body’s water balance.

Plasma Volume — The watery part of the blood that is lost in sweat. The body tries to maintain it by pulling water from other spaces in the body. By drinking fluid that hydrates, plasma volume is better maintained without pulling from other spaces.

Why Separate Fuel And Hydration? When food or fluid is consumed, osmolality changes in accordance to the rate at which the nutrients are emptied from the stomach into the small intestines, which does 95 percent of all fluid absorption. Normal osmolality of the intestinal lumen — the inside space of the intestine — of a fasted individual sits between 270 and 290 mOsmol/kg. This organ is sensitive to osmotic gradients, thus the composition of a solution is critical for rapid fluid absorption. Solutions containing carbohydrates also achieve slower rates of water absorption and less plasma volume.

Wait, Isn’t Sugar Bad? To maximize water absorption, beverages formulated with glucose and sucrose enhance fluid uptake via co-transport mechanisms — when two substances are simultaneously transported across a membrane by one protein.

Clean Sport — Ingredients that level the playing field, are safe for sport, unbanned, get audited and contribute to less waste and fewer plastic bottles. Clean Sport also includes supporting and sponsoring clean athletes.

Look On The Label — Sugar substitutes to avoid include sorbitol, mannitol, xylitol (the sugar alcohols), acesulfame potassium, aspartame, neotame, saccharine and sucrolose.

Water Won’t Cut It — Plain water is associated with a poor rate of water absorption, due to the outward flow of sodium, pulling both water and sodium into the lumen.

At Rest — Once Sims and Nuun finalize their 2017 formula, their next project will look at the unique hydration needs of the body in action versus at rest.