How Caffeine in Sport Drinks Affects You

It is summertime – time for long hikes, lake swims, trail runs and camping trips. While you’re on your many mile treks in the warm weather, you probably consider dehydration. Perhaps you just drink water, but you may also carry along sport drinks to help combat the dizzying dehydration effects. But caffeine, which is touted for its ergogenic properties, can be found in some of those drinks. What does this mean for your athletic pursuits? Our resident expert on sports nutrition, Dr. Mel, is here to update us on the latest research on the potential ergogenic effects of caffeine in sport drinks.

Sport drinks are typically recommended over water for activities lasting longer than one hour. There are all sorts of variations of sports drinks on the market, so how do you decide what you need or want? What are the basic ingredients? What about extras, like caffeine?


Credit: Long Mai

Basic ingredients include glucose and electrolytes. Electrolytes are minerals or salts such as magnesium, sodium, chloride and potassium. These are key ingredients when one is active because electrolytes are lost in sweat and are required for proper muscle and metabolic function to continue to exercise. Glucose is beneficial for exercise performance and contributes to taste or palatability of a drink. Both electrolytes and glucose can make a drink more desirable than water. Although you are getting additional calories with a sport drink when you may not need it (short duration activity), it is more important that you are hydrated. Drink up!

Caffeine is sometimes added to sport drinks, which can provide additional benefits. Caffeine in even low to moderate doses (200-400mg) can improve physical and cognitive performance in most cases. Larger doses can be beneficial, but you run the risk of negative side effects like jitteriness, overstimulation and sleep disturbances.  Some folks are particularly sensitive to caffeine and may experience gastrointestinal distress (most likely, you already know who you are). But in terms of hydration, I want to emphasize that caffeine does not dehydrate you.

Caffeine is a very mild diuretic (increases urination) at rest, but with exercise the body’s water-conservation mechanisms are much stronger. We have all been told for decades that caffeine is dehydrating and to avoid it with exercise, but there are now several solid research studies to date that dispel this myth. If you consume caffeine in liquid form—in a sport drink, coffee or soda—you are consuming a fluid, so you are improving your hydration with an added ergogenic benefit.


Credit: Mike Mozart

The primary performance benefit of caffeine is a decrease in central and peripheral fatigue. In other words, it will take you longer to mentally and physically fatigue, allowing you to perform at a higher intensity for a longer time. Even in low doses, caffeine’s primary mode of action is to block adenosine in the central nervous system (CNS). Higher doses may impact metabolism, but the majority of performance benefits have been documented as a result of CNS effects. Physical benefits also include enhanced muscle contraction.

There are several cognitive benefits related to caffeine consumption, which can benefit athletes, students and everyday working adults. Caffeine increases alertness, focus, mood, reaction time, memory and vigilance. Vigilance—the ability to maintain attention and alertness over a prolonged period of time—is of special importance to military night operations and ultra endurance events that can last 24 hours or more.

In terms of caffeine in sport drinks, they are all different so it is important to try different brands, flavors and dosages to find what you tolerate and enjoy the most. Other “sport drinks” like coffee and soda are common caffeine delivery systems employed by athletes. Always experiment with new sport drinks or foods during training and not on the day of a big adventure. Stay vigilant!

-Melissa W. Roti, PhD, FACSM

For additional information, check out “Caffeine for Sports Performance: The Truths and Myths About the World’s Most Popular Supplement” by Louise Burke, Ben Desbrow and Lawrence Spriet (2013). The book provides the science behind how caffeine works and how to use it to benefit your athletic performance, while being very reader-friendly.  

Play safe out there!

Dr. Kevin

PhD, Brooks-Range Mountaineering Product Ambassador,

Assistant Professor Westfield State University

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