Sports Drinks

Sports drinks have been around for a while now. Sports drinks are of great benefit in replacing both fluid loss and carbohydrates used during sport. Although frequently cited as being most useful during endurance events, sports drinks can also enhance sports performance during interval, high intensity exercise.


The value of sports drinks is in their carbohydrate content. The carbs, mainly in the form of glucose and sucrose, delays fatigue by topping up blood glucose levels to provide glucose for the active muscles.

A sports drink should be used to provide 30 to 60g carbs per hour of endurance exercise, to help replace blood glucose. Half a litre (500 mL) of sports drink will provide around 30g of carbs.

Evidence from research suggests that a sports drink with two carbohydrate sources stimulate significantly greater water absorption than those with only one carbohydrate source.

Most sports drinks are labelled as “isotonic.” Isotonic means that the fluid has a similar concentration as blood. Isotonic fluids quickly empty from the stomach into the small intestine, where they can be rapidly absorbed into the blood stream.

It can take 10 to 20 minutes for isotonic fluids to travel from your stomach to your skin for sweating. That’s why the advice is to start drinking 10 minutes before you start sport. Never wait until you are thirsty. No fluid is instantly absorbed!

Salt (sodium) is added to sports drinks not just to replace sweat losses but to enhance the fluid absorption from the intestines.

The sodium does improve the taste of a sports drink, which generally contain 250 to 410 mg sodium/litre.

Possibly the greatest benefit derived from the sodium in a sports drink is that it helps the body retain ingested fluids rather than just ‘renting’ them. After sport, fluids need to be replaced at a higher rate than the sweat rate as some fluid will be converted to urine even if the body is still dehydrated.

Without sodium, much of the ingested fluid will pass via the urine. Taking a sodium-containing drink before exercise can also increase blood volume leading to an improvement in endurance due to the lower risk of dehydration.

Sodium is a necessary mineral for ultra-endurance athletes, in events taking longer than four hours. Under these circumstances, if sweat losses are replaced solely by a low sodium beverage eg water, the athlete may suffer from hyponatraemia (low blood sodium). All ultra-endurance athletes should include a sports drink with sodium to avoid hyponatraemia.


It is not recommended to consume carbonated (fizzy) drinks during sport. The carbonated drinks are absorbed at a much slower rate than non-carbonated drinks, such as water and sports drinks. One research group found fizzy drinks empty from the stomach three times slower than flat drinks. Carbonated drinks also give you the burps and are difficult to drink quickly.

Research using athletes shows they will generally drink more of a flavoured drink than just plain water both during exercise and after exercise. This holds true for children, adolescents and adults alike. Make sure your sports drink is the flavour you enjoy.

Drink temperature
It’s best to keep your drink cool unless you are competing in very cold conditions. If your drink can’t be kept refrigerated then freeze it so it has just thawed by the time you get to drink it. The drink temperature doesn’t appear to affect the speed at which the drink empties from the stomach and is absorbed by the intestines. So, if you exercise in cold temperatures you may prefer a warm drink.


Recreational athletes – The sugars in sports drinks can be useful in continuous aerobic activity longer than 45 to 90 minutes (if glycogen stores are well stocked before exercise). The sports drink may have value in shorter events if you haven’t eaten enough carbs before the event.

Elite athletes – Training sessions may be two or three hours long and a sports drink will be handy to get you through the session.

Endurance athletes – Due to your very high calorie needs you will need a sports drink throughout long training sessions and endurance events. A sports drink will help maintain normal blood glucose levels near the end of endurance events or long training sessions. Sports drinks also improve sprint times at the end of an endurance session. This can be particularly important in some events. For example, many long distance cycle events end with a sprint to the finish. Start drinking early to get the maximum benefits.

High intensity training athletes – When the sessions are fast and furious, glucose and glycogen are burned at a faster rate and may run out after 30 to 45 minutes of sprint training. A sports drink will let you train for longer. Drink as often as possible throughout sessions.

Tired athletes – The most common cause of tiredness in athletes is not eating enough carbs. Check you are eating enough carbs before and after training. A sports drink will help provide additional carbs.

Recovering athletes – If the session has been long and exhausting then a sports drink can help you rehydrate and re-stock your glycogen stores quickly. It’s great for endurance and elite athletes who must replace lost fluids and carbs quickly, especially if the next event or training session is just around the corner.

Athletes who don’t like water – Athletes generally drink more of a flavoured drink than just plain water both during and after exercise.

Athletes exercising in the heat – Glycogen is burned up at a faster rate during exercise in the heat, possibly due to an over-heated cardiovascular system unable to provide enough oxygen and fats to the muscles.

Sports drinks are not just for atheletes

Here are 2 good uses of Sports Drinks to treat everyday symptoms.

1. Headaches

A lot of the times, headaches can be due to tension or dehydration. An imbalance in electrolytes in the body can make headaches worse. Instead of popping pain killers, try drinking a full bottle of a Sports Drink. To keep the calories down, dilute the drink with an equal volume of water. You’ll be pleasantly surprised how quickly that takes away a headache and saves you from having to take too much medication!

2. Dehydration

Our lovely tropical island of Singapore is subject to blazing heat and high humidity. This causes excessive fluid and electrolyte loss through sweating and even breathing. We can be experiencing symptoms of dehydration without even realizing it. Symptoms include nausea, faintness, dizziness, weakness, muscle cramps ,headaches, palpitations, tingling in the fingertips etc

All these symptoms of dehydration are quickly resolved by gulping down a large
bottle of a Sports Drink.

Again, since you need a lot more water than calories or electrolytes, its a good
idea to dilute the drink with at least an equal amount of water. Since dehydration can cause nausea, its also a good idea to stay away from carbonated Sports Drinks that can distend the tummy and cause vomiting.

Darren Foo
Fitness & Lifestyle Consultant
Sports Performance Lab @ Dr Tan & Partners