What runners need to know about sports drinks

Oct 24, 2019

When you run, you lose water and salts, known as electrolytes, through your sweat. The longer you run (half marathons, marathons and pure LSD’s), the greater the loss. If you don’t drink enough to recover your sweat losses, you can become dehydrated. Dehydration is a very dangerous condition if left untreated. Always remember the importance of taking in WATER to ensure decreased risk of dehydration and electrolyte imbalances. During running, your body also uses carbohydrates for energy. Being low in energy can also affect your performance.

Consuming a sports drink will assist to correct losses in electrolytes and provide water at the same time to prevent dehydration, while at the same time including carbohydrates that will enhance performance and prevent one from hitting the wall.

Sport drinks are an easy way to have all these benefits included at the same time and allow you to can eat.

Runner drinking sports drink

The guideline for consuming a sport drink will be any vigorous training/running for more than an hour.

 Other conditions where you could benefit from consuming a sports drink include:

  • Intense exercise, such as interval training
  • When you experience a high sweat loss
  • If you are a salty sweater. One way to tell is that you’ll notice white powder on your face and clothes when you sweat
  • When training in the heat and under high humidity conditions
  • To balance energy input with energy output
  • If you are training more than once a day

To determine the correct amount of electrolytes and carbohydrate intake for you, it is important to take all of the above mentioned conditions into account. A qualified dietician will be able to give you advice on this and create a customised meal plan.

There are 3 types of sports drinks:

  1. A hypotonic drink contains less than 4g of carbohydrates per 100ml and has low osmotic pressure. This is intended as a thirst quencher. Hypotonic drinks give the athlete little energy in the form of sugars. A hypotonic sports drink is taken up by the body more quickly than just water. Ideal for shorter or less strenuous exertion.
  2. An isotonic drink contains between 4g and 8g of carbohydrates per 100ml and has about the same osmotic pressure as bodily fluids. An isotonic drink is taken up by the body about as quickly as water. They are intended to quench thirst and provide energy to the body. Ideal for endurance sports such as marathons and ultra-marathons
  3. A hypertonic drink generally has more than 8g of carbohydrates per 100ml and greater osmotic pressure than bodily fluids. It is primarily intended to supply energy. The thirst quenching effect is secondary. Hypertonic drinks are taken up more slowly than water. Ideal for use 30 to 60 minutes before sports/training/exertion and immediately after sports/training/exertion. Hypertonic drinks are also useful for athletes who find that they need a bit more energy during their training.

How to choose the correct sports drink:

  • Aim to choose an Isotonic OR Hypertonic sports drink especially when running long distances
  • Carbohydrates: Choose drinks that include a mixture of different carbohydrate sources such as glucose, fructose, sucrose and maltodextrin as far as possible, especially at the start of a long distance run or a marathon.

Some sugars will be released quickly during exercise to give you the immediate energy that you need and other carbohydrates will be released slower that will improve sustained energy levels. Do take note after 2 hours of training the glycogen stores are depleted and a sports drink which includes only quick releasing carbohydrates can be used. The guideline for carbohydrate consumption during a marathon or long distance running is 30-60 grams of carbohydrates per hour. Thus the sports drink will contribute to your carbohydrate consumption, but it is advisable to visit a dietitian to customise your plan during a marathon/race to ensure an optimal consumption.

  • Electrolytes which play an important role in water balance in the body:
  • Sodium: Sodium is lost through sweat and needs to be replaced. Having sodium in the drink also increases thirst, which helps you to drink more water and stay hydrated.
  • Potassium: Potassium is also lost through sweat.
  • Minerals:

Calcium and Magnesium are sometimes included in sport drinks that might contribute to reduce the risk of muscle cramping

  • A good sports drink does not need to include added amino acids, oxygen, caffeine or herbal ingredients.

It is advisable to not take Fizzy drinks and sodas to replenish your electrolyte imbalances that occur during running, due to a lack thereof. If chosen to have fizzy drinks as part of your carbohydrate intake during a run, then it should be diluted with water and additional electrolyte intake will be necessary. Also, the carbonated gas in fizzy drinks and sodas could lead to bloating and discomfort and can make it hard to drink enough fluid during the race and to keep well hydrated.

The nutritional needs for every runner (though sticking to specific given guidelines) prior, during and after running remains to be unique…what works for one, won’t necessarily work for another.

Before you just drink during your next run, think about what’s IN that drink for you.

Choose sports drinks wisely.

Happy running!

Heste-Mari Viviers from SEMLI

SEMLI (Sport, Exercise Medicine & Lifestyle Institute) was established at the University of Pretoria in 2015, under Professor Martin Schwellnus. They enable people from all walks of life reach their full potential through health, wellness and physical activity, by providing clinical services, information and learnings backed by research evidence. Read more about Heste-Mari


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