Sunday Science: Should I Splash Out on Sports Drinks?

Fancy working up a sweat? You’d better duck into the corner shop, grab a Gator/Power/Lucoz-ade and slam it down while you exercise. According to the advertising rhetoric of the past decade or so, these drinks will turn you into strapping, hyper-efficient athletes, often capable of shooting lighting from body parts or causing cameras to spontaneously turn into gritty, slow-motion  black and white.

Are these drinks really Scientifically Proven* to Increase Performance* and Make You A Hero*? More specifically: are there any drinks capable of hydrating an active person more effectively than water, and under what circumstances? As I sat in a motorway-spanning rest stop on the coach trip back from York, sipping a lemon sport drink, a friend posed that question to me. I’ve only taken basic biology, but I’m more familiar with chemistry and solutes (and sport!) and couldn’t come up with a convincing answer either way. I agreed to investigate and report back.

As with many scientific questions, the short answer is “it’s complicated.” We absorb water from the food and drink we consume, along with the continuous bodily secretions we make: think saliva and digestive juices in the stomach. We lose water from the obvious excretions, along with moisture from our lungs during breathing, and, most importantly here, sweating.

A bit of basic biology: the body controls many of these water-related processes by manipulating the concentration of dissolved chemicals (solutes) in different locations. These solutes include salts and proteins. Water will tend to move of its own accord towards areas where these solutes are more concentrated. If a cell hoards sodium ions, for example, water will tend to ‘migrate’ into the cell from outside. The movement of water across a membrane, towards areas where solutes are more concentrated, is known as osmosis.

Osmosis will move more water when the difference in solute concentration across a membrane, such as the wall of an intestinal cell, is highest. Drinking water to rehydrate, therefore, makes sense: it contains very low solute concentrations, so the water will move across into the body efficiently.

The counter-argument, in favour of sports drinks, is that they contain electrolytes, such as salts and sugars. The body’s cells can actively accumulate these, which can help them to draw in more water. However, everything we drink passes through our stomach on the way to the intestine before it’s absorbed into the body. As a result, even a glass of pure water will pick up solutes before it gets to the intestine, depending on what we’ve been eating beforehand.

Right. So we know the basic arguments. Take a quick break, have a glass of water, enjoy the photo and then let’s run through what science has to say!

Splash goes the mandarin... no, I wasn't making a DIY sport drink!

Studying hydration is tricky. It depends on lots of variables: how the fluid is obtained (is it consumed in one big hit, or continuously, or something else), what the fluid contains (salt, sugar, protein), what kind of exercise is performed and for how long, what the time frame is and how dehydration is measured (loss of body mass, fluid balance etc).

In all of the studies I could find, the best thing that could be said about drinking water with additives was that they were useful in recovery from longer exercise sessions. For example, chocolate milk was more effective than a standard sport drink composition or pure water when used in a recovery period between sessions, as measured by endurance. However, that doesn’t tell us whether the body was hydrated better, or simply gained other benefits from the protein, sugar and salt in the milk.

Similar studies show improvements in water retention during and after lengthy exercise using sports drinks over water. This is usually attributed to the replenishment of salts lost in sweat. If we exercise and sweat a lot, we not only lose water, but salts, and our ability to internally regulate hydration may be compromised. I can personally remember a 3-hour basketball session in sweltering Queensland summer heat, when I drank 5 litres of water over the course of the afternoon and ended up feeling absolutely awful – perhaps I’d have benefited from a bit of sugar and salt to keep me topped up!

However, most exercise doesn’t to stretch to an hour or more of intense punishment, where any sports drink benefits will be most obvious. Also, simply eating a snack can help to replenish salts and sugars if necessary.

One aspect of sports drinks that does need to be mentioned is the psychological effect. Water is less palatable than a sweetened drink, and most people find it easier to drink more of a sports drink than water. When we exercise, we tend to view all beverages are more palatable, but sports drinks taste sweeter and less salty as exercise goes on, and sweeter drinks are ‘liked’ more.

For the everyday user, this is the biggest benefit of sports drinks: we are likely to drink more of them during exercise, staying hydrated based on quantity consumed, not quality. For the majority of people, though, water is cheaper, about as effective and doesn’t produce the plastic waste!

Categories: Problems, Science | Tags: , | 12 Comments

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12 thoughts on “Sunday Science: Should I Splash Out on Sports Drinks?

  1. George

    I often just make my own sports drink by diluting fruit juice and adding some salt. Seems to work okay. But to be honest, I found it hard to get the right balance, so I now normally just drink water, and take some food which hopefully will provide some of the salt and other electrolytes.

    Lovely pic btw.

  2. jakeisblogging

    You should listen to my favourite edition of Radiolab on Limits:

    There’s an interesting study in it where sports drinks were swished in the mouths of athletes, not drank just swished, and some people got fake energy drinks that tasted the same. The people that swished the real energy drink got a boost and performed much better. Very surprising result, showing that the placebo effect isn’t real for sports drinks. Not sure I agree though.

    Personally I don’t find they do anything for me. My performance is exactly the same with an energy drink or with water. You’re right, it’s all about correct nutrition.

  3. I think anyone who’s had the foresight to buy a ‘sports’ drink on the way home from a big night out will agree that they definitely have certain rehydration advantages!

    • Definitely – though that may be a specific case because alcohol does all kind of nasty things to your fluid balance, and, you’re much more likely to down a proper 600ml of sports drink than have two glasses of boring old water before bed!

      Jake – going to check it out! The element of psychology in anything biological is so interesting, and the way our physiology is controlled by indicators that may not actually measure what they are supposed to. The study, from your description, suggests that the performance was linked to the ‘health’ of the cells in the mouth, not the whole body – because swishing the drink could benefit them but would have little or no effect on muscle tissue etc.

      George – I find that too. Though most of my exercise up until this year was surfing – all you drink is salt water, no electrolyte problems there!

    • Liam Fitzpatrick

      Hang over severity I wouldn’t say is due to level of dehydration alone (both of which can’t be measured quantitatively). Hangovers are likely much worse if you danced off all your energy at the nightclub the previous night, and a replenishing dose of sugar can be what helps there. Also your mental state at the time. Waking up alone at home with nothing to do the next morning makes the hangover seem much worse than if you passed out on the floor somewhere with mates and wake up with a mentally stimulating circumstance before you!
      Also, I hear a vallium before bed can eliminate hangovers ;) but it hardly rehydrates.

  4. I don’t need a Sports Drink to make me a Hero…I already am one

  5. Liam Fitzpatrick

    The Powerade bottles claim to have scientific evidence by NSWIS to back up their ‘iso-tonic’ claims. But the article cannot be found either by searching the powerade website or the NSWIS website. I did find it after using Google to search the NSWIS website for the term ‘powerade’:
    The main issue with this is that only 6 subjects were tested. They performed the tests on a rowing machine with both Powerade and placebo, one after the other, in a randomised cross-over way. But the details of the randomisation aren’t given. With only 6 subjects, that means there is only a 31% chance that 3 powerades and 3 placebos were in the first round. What if they just omitted the fact that the 6 powerades went first?
    Also, the performance could be simply because powerade has sugars in it. Drop a tablespoon of cane sugar into your water bottle for a similar boost of sucrose.
    My uni statistics knowledge tells me this is not sufficient evidence for putting on bottles everywhere that it improves performance, and is fooling all the unknowing and often unquestioning sport-interested fratboys out there.
    Main thing however is that with only 6 rowing subjects, it is not a sufficiently big enough sample of the population for statistical proof. It doesn’t eliminate confounding variables. It’s quite easy to test more, so why don’t they?!

    • Good point, and a good question. Companies with their kind of financial resources could easily, if they wanted to, run substantial sized trials with a range of sporting activities and athlete types. However – as they say in the conclusion of the abstract you link – they’re probably effective because they contain sugar, not because of their ‘isotonic’ properties.

      It sounds cynical, but also true, that they do a test that gives them a significant result, and put a word on the indicator they measure like ‘performance’ and then market it. More widespread testing might give less marketable results…

  6. M@

    Indeed; an isotonic sports drink works best if you’re an athlete working your body to an extreme level (e.g. >80% VO2Max).

    Unfortunately a lot of the brand sports drinks aren’t actually isotonic, they’re hypertonic – with too much sugar to maximise the taste for human consumption. A true isotonic solution isn’t actually that nice to drink – and is often used to treat severe diahorrea cases (I’d love to see if Gatorade ever use that as a selling point!)

    The formulation of Gatorade isn’t patented. Only the Gatorade brand name was trademarked out to Pepsico etc so that they can commercialise sports drinks and profiteer off the brand name.
    Even though companies tend to overstate the benefits of drinking their drink, I don’t think that’s exactly what the drink companies are fundamentally trying to sell us…
    They really want to sell us something new and different… to set it apart from the rest. Companies want to own the psychological ‘head-space’ of winning, elite-fitness, stamina etc. Most importantly, a diversification of their available products to the consumer, empowers us to make decisions.

    (Gatorade became a registered trademark once the University of Florida’s football team the ‘Gators’ attributed their win at the Superbowl to their exercise drink developed by their exercise physiology department; it’s fabled that the team were suffering poor problems with stamina, and the researchers believed that it had something to do with a loss of salts, not necessarily water.)
    *Recently, some doctors in PNG investigating mysterious cases of death of ordinary Australians on the Kokoda trail, found that people were drinking too much water (over-enthusiastically keeping their water levels up)! As a result they were throwing their salt levels down too much, and dieing from acute cerebrospinal oedema.

  7. Good point about diversification of products. Why just have a sports drink that works well when you’re exercising? Why not also have a generic version which you can drink at other times, to show the world how sporty you are?

    For some reason I find myself buying them on occasion if I don’t have a bottle of water with me, because I abhor paying for bottled water. Irrational, perhaps, but somehow a lemon flavour goes some small way to justifying the £1.

  8. I am not surе where you are getting your info, but great topic.
    I needs tto ѕpend some time learnong more or understanding mогe.
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