Water or Sports Drink?

Is there any reason to choose a sports drink over water? Is it a waste of money and just a profit machine for the manufacturers? Let's use the very scientific phrase – it depends!

In summary, water is sufficient for most workouts lasting less than an hour, especially if the intensity isn't extremely high. However, for longer or more demanding sessions, sports drinks become an effective way to supply fluids, electrolytes, and carbohydrates, which help maintain performance, delay fatigue, and reduce the risk of both dehydration and energy depletion. The choice of sports drink also matters, as different carbohydrate mixtures can significantly impact both energy absorption and gut comfort.

Let's start from the beginning!

Recommendations for Fluid Intake

• Drink regularly: 150–300 ml every 15–20 minutes is commonly recommended, not only to ensure a steady supply of fluids (and potentially energy) but also to prevent fluids from lingering in the stomach, which can cause issues (1).
• Practice your fluid intake: use urine color and body weight as indicators to assess your fluid balance.

Consuming too few electrolytes increases the risk of heat stroke. When your body temperature rises, it tries to protect itself by making you feel tired, which reduces intensity and heat production. The downside is that lower speed or intensity can worsen your performance — and it's completely unnecessary.

Additionally, the risk of hyponatremia (salt deficiency) rises when you drink large amounts of water without replenishing salts. Salts and minerals serve several essential roles. For instance, sodium facilitates the transport proteins required to move fluids and glucose into the bloodstream (3). A lack of sodium causes fluids to pass through the body, flushing out sodium (4). In milder cases, this can lead to dizziness, confusion, and nausea. If unchecked, salt deficiency may cause cerebral edema, which has tragically led to fatalities in the worst cases.

During shorter distances and training sessions lasting less than 60 minutes, there's no urgent need for a sports drink to maintain your performance. It's often sufficient to rinse your mouth with the sports drink and rely on the amount of stored glycogen in your muscles and liver.

Let's illustrate with a calculation example.

Consider a 75 kg runner maintaining a 4-minute pace and keeping around 80–85% of their maximum heart rate. This runner will burn approximately 1000–1200 kcal/hour. At such high intensity, nearly all energy is derived from stored muscle glycogen. It requires about 300 grams of glycogen in this scenario, roughly the amount you can store in your muscles. This is what makes the sports drink so crucial. While your glycogen stores can never be fully depleted, running at a high pace leaves you almost energy-exhausted after an hour.

The previous generation of sports drinks could only deliver 60 grams of carbohydrates per hour because the stomach and gut couldn't handle larger doses. The new generation of sports drinks, with multiple carbohydrate sources, can deliver 100–120 grams of carbohydrates per hour. Though you can never fully compensate for the energy loss during intense physical activity, you can double the time to exhaustion with a balanced and calculated energy intake. It's a massive advantage: it increases your total training volume, improves workout quality, and speeds up recovery.

These are three key factors that help you become a better athlete in your sport.

Sian Welch & Wendy Ingraham were both almost completely glycogen-depleted but still fighting for 4th place in the 1997 Ironman.

The important aspect is how long you're out sweating. If you're out for over an hour, the intake of fluids, electrolytes, and carbohydrates becomes significant. As training time increases, so does the need for additional electrolytes and carbohydrates. Sweat contains a lot of salt and minerals that regulate bodily functions and are crucial for health and performance.

Compensating for the loss of salts and minerals via sweat is important for several reasons: too low levels of fluids and electrolytes reduce blood volume, force the heart to beat faster (i.e., increase heart rate) and thus lower performance. In this situation, it's essential that the sports drink is easy to drink and doesn't leave a sticky, overly sweet feeling in your mouth.

When researchers examined the difference between water and various sports drinks, the results were clear. Cyclists who rode for 2 hours performed 19% better with a sports drink composed of different carbohydrate sources compared to a sports drink with only one carbohydrate source. Even more interesting is that the difference between sports drinks was significant: the cyclists performed 8% better with a glucose/fructose-based sports drink.

So, it's not just about the difference between drinking water and a sports drink; there's also a significant difference between various sports drinks. From experience, many athletes have long noticed that they have fewer gut issues with sports drinks based on corn starch than with barley starch. As far as we know, no research has compared this directly, but it might be worth considering if your stomach acts up.

1 – The importance of volume in regulating gastric emptying. – http://www.ncbi.nlm.nih.gov/pubmed/1875801

2 – Fluid and fuel intake during exercise. http://www.ncbi.nlm.nih.gov/pubmed/14971432

3 – Nutrition for endurance sports: Marathon, triathlon and road cycling. http://www.ncbi.nlm.nih.gov/pubmed/21916794

4 – American College of Sports Medicine position stand – Exercise and fluid replacement. http://www.ncbi.nlm.nih.gov/pubmed/17277604.

5 – Wilmore et al (2012). Physiology of sport and exercise. Leeds: Human Kinetics: 378-385