Why sports drinks may not be enough to stay hydrated
Jul 31, 2018
Endurance athletes who compete in long-distance events of two-to-three hours or more will inevitably face the reality of nutrition planning and execution. During exercise, our bodies rely on a mixture of energy (calories), water and electrolytes to keep moving, and when we run out of reserves, performance quality must necessarily decrease. A reasonably fit athlete, starting with optimal levels of hydration and glycogen, can sustain approximately two-to-three hours of exercise in ideal weather conditions before being forced to slow down (colloquially termed as “hitting the wall”) due to resource depletion. In order to maintain output, he or she must replace the “fuels” of calories, water and electrolytes throughout the period of exercise. Sports drinks, which contain simple carbohydrate, water and salt, may appear to be a sufficient as a source of fuel. However, this is not true in all cases as you will see below. In this blog post, we provide an overview of the role electrolytes play in keeping athletes moving, as well as an explanation for why sports drinks alone may not be enough to stay hydrated.
Why do I need electrolytes?
One of the most common questions asked by beginner and even intermediate athletes references the need for electrolytes in the first place. Electrolytes – by which we mean a combination of sodium, potassium, calcium, magnesium and chloride – are crucial for a variety of physiological functions, including the maintenance of blood pressure and proper neuromuscular skeletal functioning, or the functioning of the nerves, muscles and bones. We also lose electrolytes through sweat. This means that inevitably, if we are not replacing those electrolytes during the course of exercise, we will run out of them, or at the very least, stores will become so low that performance will be hampered. The body has a finite store of electrolytes (by definition) and in fact much of that quantity is bound and unavailable to the bloodstream in a short time frame. The depletion and lack of electrolytes commonly manifests itself through cramping, headaches, nausea and fatigue. In more serious situations, it can lead to coma or even death. Bottom line: Just like calories and water, which are also crucial to the ability to continue exercise, the body needs electrolytes to function. Therefore, after a certain point of depletion, you need to replace electrolytes or you will be forced to slow down or stop.
When should I start replacing electrolytes?
Except for extremely hot and/or humid conditions, if you are exercising for 60 minutes or less, you will likely be able to rely on your diet alone to replenish any electrolytes you lose through sweat. Western diets are usually high in sodium, with additional electrolytes commonly found in fruit, nuts and whole grains. Essentially, a healthy diet will suffice. Given the predominant loss of sodium over the other electrolytes, replacement can be focused on this mineral in particular, if needed. Additionally, if you are exercising for less than an hour, you will be finished before your performance becomes significantly impacted due to low salt levels. However, as you approach longer exercise times, you will need to begin replacing electrolytes – along with calories and water – during the course of your race or workout. Your physiology and fitness level will ultimately determine how long you are able to exercise without fuel, but for most people, the maximum time recommended in the literature is 90 minutes. For additional details, we recommend that you check out our usage guides here.
Longer distances require greater precision
The human body is incredibly adept at managing nutritional stores, meaning that up to a certain point, an athlete can fumble his or her way through nutrition and still maintain decent performance during training or racing. However, the longer you go, the more nutritional precision matters. If you are not replacing calories, water and electrolytes with some alignment to the rate with which they are being consumed/lost, your performance will suffer. Importantly, you cannot simply “make up” for bad nutritional habits several hours into a race. Suddenly realizing you have not consumed enough calories does not reverse the fact that you are now depleted of glycogen and you will have to slow down for the time being while you attempt to eat more food and raise your blood sugar levels. Studies have indicated upper limits on absorption rates, in particular for energy, at about 300-400 kcal/hour. As a general recommendation, we suggest replacing between 50-80% of the water, energy and electrolytes lost per hour. Ideal nutrition looks similar from start to finish. Sometimes, in very long races, athletes will shift from solid foods to liquid foods over the course of the day, but the ratio and amount of calories, water and electrolytes will likely be similar in the first hour of racing as in the last hour. Additionally, potassium, calcium and magnesium losses become more significant with longer distances, and their replacement becomes more important as well. This process is incredibly difficult to get right, and it is sometimes why eating is called the “fourth sport of triathlon.” Bottom line: Everyone’s body has unique needs, and even variable day-to-day, and therefore, it will take some experimentation to find what works best for you. The key thing to remember is that as you approach longer distances and times, you must get more precise in your fueling, and more important to adjust your fueling plans based on your biofeedback.
Why sports drinks may not be enoughAs noted above, a key aspect of endurance fueling is the need to replace calories, water and electrolytes as they are consumed/lost. The process is similar to a two-stroke engine: If it requires two parts oil to 10 parts gasoline, adding extra gasoline will result in mechanical failure if you do not add the necessary amount of oil. Consider electrolytes to be the oil of an engine! It works the same way in endurance fueling. Sweat typically has about 1,000 mg sodium/liter, but due to concerns about taste, a typical sports drink has only 440 mg sodium/liter. Otherwise, the product would taste like seawater. Simple math illustrates that if, during the course of training, you ingest nothing but sports drinks (or worse, water), your electrolyte stores will become too low compared to your water stores, a medical condition known as hyponatremia. Additionally, many sports drinks also do not address any form of supplementation of the other key electrolytes, including potassium, calcium and magnesium, which further offsets the balance and can potentially cause additional cramping and muscle issues. To see this in action, consider the results of a small double-blind, placebo-controlled 2015 study, which found measurable performance improvements in athletes who replaced adequate amounts of sodium compared to athletes who did not. The science behind SaltStick: In 2015, researchers at Camilo José Cela University (UCJC) divided 26 medium-distance triathletes into two groups:
- The first group completed a middle-distance triathlon (1.2 miles swimming, 56 miles biking, 13.1 miles running) consuming sports drink, but also consuming SaltStick Caps to help replace sodium.
- The second group completed the same distance while consuming sports drink, but they received a placebo capsule with no extra sodium.
Researchers were aiming to replace about 70 percent of sodium in the first group, but only about 20 percent in the second group (the difference solely due to SaltStick). After the race, researchers found the athletes who consumed the SaltStick Caps finished in an average of 26 minutes faster. The increase in speed usually came from improved cycling and running times, which come later in the race after electrolyte levels begin to decline. A 26-minute boost in performance is no small feat in a race that typically takes five to six hours. And the only difference is that the faster athletes properly fueled themselves! Additionally, as we noted above, precision matters more over longer courses, so these results could have been more pronounced if the subjects completed a full-distance triathlon or an ultramarathon.