Why do we need to drink more fluids in hot weather or when we exercise?

The body sweats so that it can maintain its core temperature at 37 degrees centigrade. But this results in the loss of body fluid and electrolytes (minerals such as chloride, calcium, magnesium, sodium and potassium) and if unchecked will lead to dehydration and eventually circulatory collapse and heat stroke. The effect of fluid loss on the body is as follows (Rehrer 1994) [source]:

% body weight lost as sweat | Physiological Effect
2%                                              Impaired performance
4%                                              Capacity for muscular work declines
5%                                              Heat exhaustion
7%                                              Hallucinations
10%                                            Circulatory collapse and heat stroke

Lots of people die of heatstroke during the hot humid Japanese summer, so do read Yomiuri Shimbun’s “Preventing Heatstroke: replacing fluids a key measure” which also shows you how to make your own rehydration drink.

Sports drinks are different from energy drinks.

What are sports drinks?

There are three types of sports drinks:

  • Isotonic drinks contain fluid, electrolytes and 6 to 8% carbohydrate – they quickly replaces fluids lost by sweating and supplies a boost of carbohydrate. This drink is the choice for most athletes – middle and long distance running or team sports. Glucose is the body’s preferred source of energy therefore it may be appropriate to consume Isotonic drinks where the carbohydrate source is glucose in a concentration of 6% to 8% – e.g. High Five, SiS Go, Boots Isotonic, Lucozade Sport.
  • Hypotonic drinks contain fluids, electrolytes and a low level of carbohydrate – they quickly replaces fluids lost by sweating. Suitable for athletes who need fluid without the boost of carbohydrate e.g. jockeys and gymnasts.
  • Hypertonic drinks contain a high level of carbohydrate – and used to supplement daily carbohydrate intake normally after exercise to top up muscle glycogen stores. In ultra distance events, high levels of energy are required and Hypertonic drinks can be taken during exercise to meet the energy demands. If used during exercise Hypertonic drinks need to be used in conjunction with Isotonic drinks to replace fluids.

Here are a few links to some really yummy recipes for homemade sports drinks ~ Chicago Tribune’s recipes; Dr Lorraine Williams (aka The Track Mom) recipes; a high quality athlete’s sports drink recipe Or you can find all of the above recipes all conveniently on one page posted here.

What are energy drinks?

Energy drinks are beverages purported to boost mental or physical energy, that generally contain large amounts of caffeine and other stimulants. Many also contain sugar or other sweeteners, and may or may not be carbonated (Wikipedia).

Energy drinks typically contain more caffeine than a cup of coffee… “The average cup of coffee contains about 75 milligrams of caffeine; Red Bull—an energy drink at the lower end of the jitter scale—contains 80 mg. In contrast, an 8.4 oz can of Spike Shotgun houses a whopping 350 mg of caffeine” (source).

What about water or orange juice?

Chemistry.about.com says water is better than sports or energy drinks or any other drink for that matter, for hydration purposes (the problem is getting anyone to drink enough of it). “The natural choice for hydration is water. It hydrates better than any other liquid, both before and during exercise. Water tends to be less expensive and more available than any other drink. You need to drink 4-6 ounces of water for every 15-20 minutes of exercise.”

As for OJ (orange juice) or any kind of 100% fruit juice, it contains fructose which is not a good fuel for sports. According to research, mixing different kinds of sugars to get multiple sugar types including fructose in a sports drink during endurance exercise would be most beneficial to the athlete. (Source: D’Alessio D, Tappy L. Carbohydrate and exercise performance: the role of multiple transportable carbohydrates. Current Opinion in Clinical Nutrition & Metabolic Care. 2010 Jul;13(4):452-457).

You want the sugars to be less than 50% fructose because high fructose: Less than 50% fructose content is recommended. Honey is about 40% fructose (the Honey Board). Agave syrup (~80% fructose) or apple juice (~66% fructose) would be poor choices. High fructose gives rise to GI distress (causing e.g. running “stitch” or abdominal cramp problems) because according to the Sport Factory,  “fructose, however, has a slower absorption rate, and in large quantities, is likely to cause GI distress than any of the other carbohydrates”..

(Obesity concerns: Fructose as part of mixed carbs during exercise is beneficial to the athlete and because of the high energy expenditure unlikely to be harmful. Source: Johnson RJ, Murray R. Fructose, Exercise, and Health. Current Sports Medicine Reports. 2010 Jul;9(4):253-258.)  Maltodextrin + fructose is better than maltodextrin alone in maximizing energy to the athlete. (Source: Wallis GA, Rowlands DS, Shaw C, Jentjens RLPG, Jeukendrup AE. Oxidation of Combined Ingestion of Maltodextrins and Fructose. Medicine & Science in Sports & Exercise. 2005 Mar;37(3):426-432.)

Are sports drinks better?

In this Guardian article, Sports drinks: vital for hydration or a waste of money?, Sam Murphy reveals useful tips on how much fluid you need to drink before, during and after exercise, and whether water does the job just as well as sports drinks:

“It depends on the intensity and duration of your workout. “Water is generally sufficient for shorter sessions, but for exercise lasting more than 60 minutes, an isotonic sports drink is recommended,” says Wendy Martinson, registered dietician and sports nutritionist.

But Nick Morgan, head of sport science at Lucozade, believes sports drinks can be useful for shorter workouts, too: “If you’ve had a good high-carbohydrate meal in the three-four hours before your workout, you probably don’t need a sports drink”, he says. “But if you haven’t eaten for ages – if, for example, you’ve just got up or have hit the gym straight after work, a sports drink will provide a little extra energy, helping you get more out of yourself and reducing your ‘perception of effort.'”

Just for the record, a study in the Journal of Applied Physiology found that consuming an isotonic sports drink increased treadmill running time to exhaustion by 27% in recreational runners.

What should I look for in a sports drink?

According to Martin Gibala, an associate professor of kinesiology at McMaster University in Canada, there are two key ingredients in a good sports drink: “Carbohydrate, which provides fuel for working muscles, and sodium, which helps to maintain fluid balance.”

But formulation is key. An isotonic drink (such as Lucozade Sport or Gatorade) contains a 6-8% carbohydrate solution, which is absorbed into the body more rapidly than water, as well as providing energy. A sports drink should also contain approximately 50mg of sodium per 100ml, along with smaller amounts of the other electrolytes, such as potassium and chloride, which are lost in sweat….”

Read the rest of the article here

Why do people drink energy drinks?

The results of a recent study concluded that drinking Red Bull “can increase feelings of stimulation, decrease mental fatigue, and decrease reaction times on a behavioral control task…”

See: Howard, Meagan A.  and Marczinski, Cecile A., Red Bull May Decrease Reaction Time, 2010 American Psychological Association 2010, Vol. 18, No. 6, 553–561 1064-1297/10

This study examined the immediate effects of consumption of a popular glucose drink, Red Bull, on behavioral control. Behavioral control is the ability to perform a particular task that a person wants to perform and also the ability to discontinue a task a person does not want to perform. The researchers also assessed the reduction in mental fatigue and improvement in concentration after drinking Red Bull. The results indicate that drinking a glucose energy drink, like Red Bull, “can increase feelings of stimulation, decrease mental fatigue, and decrease reaction times on a behavioral control task,” according to the authors.

Acute Effects of a Glucose Energy Drink on Behavioral Control
Publication Journal: Experimental and Clinical Psychopharmacology, 2010
By Meagan A Howard; Cecile A Marczinski; Northern Kentucky University, Highland Heights, Kentucky

Energy drinks good or bad? by Dano Angelo White Excerpt follows on below:

“Not to be confused with sports drinks, these trendy beverages are a dangerous mix of sugar, chemicals and stimulants. We won’t keep you in suspense – they’re no good!  …

Why They’re Really Bad
The dangers about these drinks are real. Such as this tragic story where drinking 2 energy drinks in a day was suspected to contribute to the death of a 14 year old girl.

Energy drinks are sold as dietary supplements, not beverages. This means that they aren’t subject to the same scrutinizing safety standards as food and drinks.

At best these drinks are too high in sugar, which is no good for your waistline. The calorie free versions (full of artificial sweeteners) are also a joke – how can something with no calories give you energy?

It’s easy to confuse a stimulant boost with “energy.” The major difference is – energy is real fuel, and stimulants only have a short-lived effect on your heart rate.

Aside from all those sugary calories, side effects of drinking energy drinks include increased anxiety and dehydration. Here are just a few of the potentially dangerous ingredients:

Caffeine: Can cause increased heart rate, anxiety, upset stomach and dehydration – many drinks have 2 to 5 times more caffeine than a cup of coffee.
Guarana: A caffeine-like product that compounds the stimulant effect.
Taurine: Promoted to help with focus, taurine, may have a sedative effect. Used to treat high blood pressure and congestive heart failure– very little is known about the safety of high-dose or long-term use.
It’s also become trendy to mix energy drinks with alcohol; this creates a dangerous combination of “uppers” and “downers” that may result in dangerous cardiovascular and neurological side effects.”


Do you really need energy drinks? By coach_jon | Fit to Post Health – Sun, Jun 24, 2012.

Have you ever taken a look at the ingredients of most energy drinks? Yes I know they sponsor major sporting events and famous athletes, but are the good for you or are they simply hype?

For everybody who does serious exercise, we know it can be very tiring physically. And I know of people that sometimes take a stimulating “energy drink” to get themselves ready for a hard training session.

I don’t particularly like this strategy.

Look at the ingredients of a typical energy drink. The stimulant is of course caffeine. I have actually no problem with this, in fact coffee is good for you pre-workout with some heavy cream (which is fat that slows the absorption) so make it a slow release fat burner and energy drink. Caffeine is quite well researched in science and in practice to increase the ability of your body to exercise.

Here is the problem…

Most energy drinks have caffine + sugar. This means a sugar + caffeine RUSH and the resulting downer after that.

Not only does this give you a downer, energy drinks have… taurine. Do you know who I recommend taurine to? Clients who can’t sleep. It’s a down regulating nutrient. Now why would that be in an energy drink?
To give you a bigger downer soon after your caffeine/sugar high. Guess what happens after that? You buy another energy drink. This is great for sales. That is some sneaky ingredient usage there, isn’t it? Buyer beware.

Ok, so what should you drink before a hard training session?

I do like caffeine from coffee, but try to take it with heavy cream so that you don’t get that caffeine all at once.

Water is of course critical. A good guideline is that you should weigh more after your training session than before. A good indicator that you drank enough. A 1.5% drop in bodyweight can lead to a 10% drop in power output. So water is critical, especially in the hot weather we have here.
Finally, you can take pure electrolyte salts, not the sugar laden energy drinks. Electrolytes are excellent for preventing cramps and help muscle contractions. Get them in pure powder form, with no sugar. In fact a good electrolyte solution tastes slightly salty not sweet.


Now that you know the difference between water, a sports drink and an energy drink, you might want to know the Seven Rules for Hydration (Troop 1994)


Further reading:

In the article Energy Drinks – Good Or Bad Christopher Puetz lists the following “no-nos” found in energy drinks:

“Now let’s look at one of the worst offenders that is used in so many foods: High Fructose Corn Syrup. Well, if you want belly fat this product is the best way to get it. Empty calories, hard to process by your body and simply just bad. Ever since soft drink makers switched to high fructose Corn Syrup America’s populated literally “expanded”. Sugar is much less worse than high fructose corn syrup.

Artificial sweeteners are suspected of having several health impacts. Besides under suspicion to cause cancer they also are suspected lead people to eat more of other foods and eventually gain more weight that weight “because they saved so many calories before”.

Another ingredient we need to look at is caffeine. Caffeine does not provide energy, it only stimulates your central nervous system. Also, if you already consume caffeine several times per day, an energy drink will not really have any caffeine based effect on you as your body is already accustomed to the substance anyway and you would need to take way more than one energy drink to feel the effect of caffeine.

Artificial vitamins coming from energy drinks are not worth the effort. They are hard to absorb by your body and the amounts provided are useless.”

Energy Drinks- Good or Bad? By Gregory Bandolik on Aug 30, 2010

Are “Energy” Drinks Just a Load of Bull?
By Rachel Lippmann-Turner on Sep 26, 2011

This next article deals with health implications and Harmful effects of energy drinks but also mentions the possible benefits, depending on the specific ingredients.

“Energy drinks also tend to be packed with a lot of fructose and sugar, which can often have laxative effects on your body. Sugar causes your energy levels (or insulin levels) to come crashing down once the sugar leaves the bloodstream. Energy drinks high in sugar are good for a short-term buzz, as they stimulate your nervous system quickly, which usually makes you feel more energetic at first. However, the sugar is used up in a short period, and the drinker is often left feeling more fatigued than they were to begin with. If your drink contains high amounts of sugar, regular consumption will lead to dental health problems such as cavities.

Caffeine is known to have both laxative and diuretic effects on the body, which means you often lose the stimulant through excess urination and are left dehydrated. Caffeine also increases your heart rate and body temperature. Too much of this stimulant can cause an irregular heartbeat, excess sweating, jitters and anxiousness, which is hardly ideal if you want to concentrate for an exam or get in the mindset for a competitive event.
On top of that, high amounts of caffeine can reduce your coordination and balance. Too many energy drinks with caffeine will disturb your sleeping patterns. These are the reasons that top the list of why children, pregnant women and people with heart conditions should avoid energy drinks.
If the side effects of energy drinks alone aren’t enough to deter you, then add some alcohol to strengthen the negative effects. Mixing energy drinks with booze causes further dehydration. This explains why raver kids are passing out at dance clubs.
Energy drink cocktails cause drowsiness, loss of coordination and slow reflexes. To make matters worse, when you’re pounding back energy drinks and alcohol it’s hard to determine just how much booze you’ve actually taken in. As a result, your blood alcohol concentration will often rise in conjunction with your energy and bravado – therefore you won’t even realize how much alcohol you’ve consumed, and might try to do something stupid – like drive home.
However, energy drinks aren’t all doom and gloom. There are some known positive side effects as well. For instance, drinks that contain Echinacea are said to help bolster the immune system, while energy drinks containing Ginkgo biloba and ginseng are thought to improve memory.”

Watch Discovery Channel’s excellent programme Water, Energy Drink, Sports Drink vs OJ experiments to see which works best and is most effective for sports.