I recently read the report published in the British Medical Journal (BMJ) on sports drinks. I was shocked to see how many of the popular beliefs surrounding sports drinks and hydration are wrong or unproven. In this article I will summarise the lengthy report and give you helpful tips based on the conclusions.
The key claims the BMJ research wanted to address were on the issues of dehydration and improving performance. Sports Drink Manufacturers (SDMs) have claimed that their products are better at combatting dehydration than water, that thirst is not a reliable indicator of dehydration, that dehydration is a major danger when exercising and that water alone will not combat dehydration. On the issue of sports performance they have claimed that their products will produce better performance in sport, using sports stars across many sports to promote their message.
The BMJ is an impartial publication for the medical profession that has no agenda other than informing doctors with useful information. It publishes details of where it gets all its information and declares any conflicts of interest its authors may have. Research is also open to Peer Review, meaning anyone else can see the research they have and look for flaws or inaccuracies in its conclusions. In writing the report they contacted the producers of the biggest sports drinks, namely Lucozade, Gatorade and Powerade to ask for the research they use to back up their claims and also to allow them to respond to the BMJ findings.
One of the most striking differences between the ethical approach taken by the BMJ and much of the research on sports drinks is in the area of neutrality. The BMJ found virtually all research on sports drinks was commissioned by major SDMs. They also found that scientific journals where most of this research was published had strong links with SDMs and that SDMs sponsored most major sports science conferences related to hydration. The SDMs also sponsor major sports bodies or athletes.
The BMJ research even found suggestions that negative research from independent sources may struggle to get published in major sports science journals. This is because of the close links the SDMs have with these publications and the damage it might do to the relationships.
However, the BMJ did acknowledge that getting funding for any kind of sports science research is very difficult. Sports scientists need funding for research, so inevitably they have to take money from commercial companies such as SDMs in order to survive. In their research, the BMJ spoke to scientists with current ties to SDMs, previous ties but none current and wholly independent researchers.
The SDMs have commissioned many studies on the benefits of drinks containing sugar and salt, the key components of sports drinks. When approached by the BMJ only the producers of Lucozade were prepared to share their data; the makers of Gatorade and Powerade declined. There were many inherent flaws in the research including very small trial groups (a median average of just nine people per trial) and a lack of good practice. For example research didn’t use ‘blind trials’, meaning an athlete knew when they had a sports drink and so would feel better, leading to better performance (the placebo effect). Many tests also had unrealistic conditions to assess sports performance, such as tests conducted indoors with no airflow, so athletes couldn’t cool down properly through sweat evaporation or athletes performing tests after long periods without food or after heavy exercise. Overall the BMJ found most of the tests were unreliable and that the results they produced did not clearly demonstrate the claims being made.
Benefits of Sports Drinks
Looking at each of the significant claims in turn, I will now address the BMJ conclusions.
Claim 1: Thirst is not a reliable indicator of dehydration
The issue of thirst, dehydration and sports performance has been mainly a marketing construct by the SDMs. Ideas such as using urine colour to assess dehydration only apply first thing in the morning and at other times offer no accurate guidance as to hydration status. There is no evidence to suggest that thirst is an indicator that an individual is already dehydrated or performance will be diminished if they feel thirsty. In fact studies showed thirst was the best guide as to when fluid is needed and when it isn’t.
Claim 2: Sports Drinks are better at combatting dehydration than water
Although this is one of the key claims made, the evidence supporting this is inconclusive. The theories draw on broad principles such as osmosis but are unproven in real life or are based on concepts such as sweet tastes make you want to drink more. As previously mentioned, much of the research to prove these claims is poor and the positive results minimal or non-existent.
Claim 3: Dehydration is a major danger when exercising
This was the most dangerous myth of all. Although dehydration can kill, this will almost always be in a survival situation where lack of access is the problem. If you’re lost in a desert you will feel thirsty but be unable to drink due to a lack of water. If you’re playing sport and feel thirsty your body will compel you to stop and seek fluid, which is nearly always available. Dehydration kills when there is no water available, not because people have not drunk enough when it is available.
The researchers looked at marathon running where people are repeatedly warned against the dangers of dehydration. They did not find a single case of death due to dehydration. Not one. They found 16 deaths due to drinking too much water and 1600 cases of critical illness due to over-hydration. Illness and death from drinking too much water is called Hyponatraemia. Hyponatraemia is actually the dilution of electrolytes from drinking too much water. If you exercised for several hours without eating anything and drank large amounts of water then you could be at risk of Hyponatraemia. However this is highly unlikely except for extreme ‘Ultra’ athletes and it is not dehydration but too much water that would kill you.
Claim 4: Water alone will not combat dehydration.
There was no proof that the sports drinks were any better at hydrating than plain water. There was no proof that water can’t hydrate you-a ridiculous claim when you think about it. Sports drinks containing electrolytes would be beneficial for Ultra athletes to combat Hyponatraemia, as mentioned above, but the drinks are bot combatting dehydration. Normal people playing sports for up to two hours or 60-90 minutes in extreme heat will not need extra electrolytes.
Claim 5: Sports Drinks improve sports performance
There is research that demonstrates consumption of carbohydrates during sustained periods of high-intensity endurance exercise will improve performance. In brief, drinking sports drinks will help if training hard for 75 minutes or more. Therefore Bradley Wiggins cycling for seven hours in the Tour de France or Paula Radcliffe running a marathon will benefit from sports drinks. However Jessica Ennis (longest continuous event is 800m or just over two minutes) or David Beckham (football is stop-start with a 15 minute half-time break) will get little benefit.
Sports stars such as Ennis or Beckham are used to promote sports drinks because they add credence to the message the SDMs want to send out. However many of these sports stars will not need or use sports drinks when competing in their sport, although they may in preparation, when training for prolonged periods.
Bringing this into the realm of mere mortals, a sports drink will give no benefit to the average gym-user or recreational footballer. Only if you are training continuously at a high-intensity (a level where talking is challenging and you sweat vigorously), and for more than 75 minutes do you need to use sports drinks. Sports drinks contain carbohydrates in the form of sugars. Having unnecessary sports drinks is no different to having unnecessary cakes or chocolate and will cause weight gain if you consume more calories than you need.
So what should you do?
In the absence of solid evidence in favour of sports drinks and with some proven disadvantages, I would make the following recommendations:
For more information on the research behind this article consult the British medical Journal 18 July 2012