It isn't which brand you drink, but how you drink it. Energy drinks are beneficial to those that exercise or compete for periods of 60 minutes or longer, or exercise in warmer temperatures. The way that the body absorbs nutrients and fluids is affected by the rate at which they are emptied from the stomach into the small intestine.
Some factors that influence gastric (stomach) emptying are that large fluid volumes in the stomach increase the emptying rate into the intestine. Other factors such as increased concentrations of solutes (sugar) and exercise intensity above 75% decreases the gastric emptying rate and may cause stomach upset, and/or diarrhea.
An athletes fluid absorption is increased by consuming low to moderate levels of glucose and the temperature of the fluid doesn't seem to play as much of a role in absorption as once thought.
Here are some guidelines to help you choose a proper energy drink...
You should avoid drinks that contain high concentrations of particles because it decreases the rate of gastric emptying. There is little difference between liquid glucose, sucrose, or starch when ingested as the carbohydrate fuel source during exercise.
Fructose is not a recommended fuel because of its slow absorption and it also promotes low fluid absorption.
A re-hydration drink should contain a carbohydrate concentration between 5-8%. Higher concentrations cause a delayed gastric(stomach) emptying and possible stomach upset or diarrhea. To determine the carbohydrate concentration in a drink, divide the carbohydrate content (in grams) by the fluid volume (in milliliters) of the drink and multiply by 100. This range usually allows proper carbohydrate replacement and without limiting fluid absorption, and temperature regulation.
Drinks that contain sodium may benefit ultra-endurance athletes by maintaining plasma osmolality, reduces urine output, and sustains the physiological urge to drink.
Consuming 400-600ml of fluid immediately before exercise increases the beneficial effect of having an increased stomach volume, and fluid and nutrient passage into the intestine. You should continue to consume 150-250ml of fluid (at 15 minute intervals) throughout exercise to replenish the fluid that is passed into the intestine and it will also maintain a large gastric volume during exercise.
The optimal carbohydrate replacement rate is between 30-60g per hour ingested at least 30 minutes before usual fatigue would have set in without a carbohydrate supplement. Maximal fluid ingestion is about 1000ml per hour to prevent dehydration without gastrointestinal discomfort.
Each athlete will have to determine which drink they like best or that will help them perform better. These guidelines should help you maintain proper hydration and optimize performance. The keys to a good energy drink are that it tastes good, offers the potential to improve performance, gets absorbed rapidly and won't cause stomach upset.