One of the most frequent questions I get asked by my clients is what they should drink during exercise, often framed by saying ‘what brand of sports drink do you think is the best’. For a long-distance runner or cyclist this can spark a detailed discussion about training duration, intensity, environment and a whole host of other factors, but for the average recreational athlete or gym goer the advice is far more simple. The question wrongly assumes that everyone who exercises should be rehydrating using a sports drink, when in fact nothing could be further from the truth.
The human body is made up of around 70% water, and it is vital for every process in the body. Whereas we can go for weeks without food (yes, really!), we can only survive for a fraction of that time without water.
One of the most critical properties of water for the exerciser is how it helps with thermoregulation. Moving muscles produce heat, and this raises body temperature. The compensatory mechanism is for us to sweat, which evaporates from the skin thus lowering temperature. When exercising in extremely humid conditions it is possible to lose several litres of fluid per hour, and this needs to be replaced.
Dehydration causes a number of problems; the body can’t correctly regulate its temperature, electrolyte imbalances can cause cramps, muscle contractions can be weaker and thus exercise less effective, we feel excessively fatigued and unable to think clearly (the brain is made up of 85% water), and can suffer with headaches or migraines.
So how much water do you need to drink? The standard advice is that the average person needs to drink around 2.5 litres water per day. Of course if you are exercising, that requirement will go up, in some cases by as much as 100%. Suggestions for those exercising in normal conditions without excessive heat or humidity are that they should consume around 500ml/hr.
Perhaps the best way to monitor your hydration status is to check the colour of your urine. I know this sounds a bit Gillian McKeith, but it is better to be aware of the fact we are dehydrated and need to consume more fluid, rather than to suffer the consequences. Urine should be pale straw colour and plentiful – if its dark, or you haven’t needed to ‘go’ for several hours, then the chances are you are dehydrated. Water is necessary for the body to remove waste products in the kidneys. If you don’t drink enough, your body will be forced to retain water to support body processes, and your urine will become dark and low in volume.
I read an article several years ago stating that 75% of the American population were chronically dehydrated. I see no reason to suppose that it would be any different in the UK, and even if those figures are exaggerated it is still a pretty shocking statistic. Assuming that some of these same people are regular exercisers, it is easy to see that they probably won’t be getting the results which they deserve from their efforts. Fluids should be regularly consumed throughout the day, and contrary to popular myth tea and coffee do count – there are many reasons not to drink too many caffeinated beverages, but the story that they contribute to dehydration is simply not true.
It is impossible to discuss hydration and exercise without touching on the condition hyponatremia, otherwise known as water intoxication. It is a serious issue which has been seen more often as significant numbers of amateur athletes take part in extreme endurance events lasting many hours (marathons, ironman races etc.). It is caused by an overconsumption of plain fluids (those lacking in sodium) leading to a severe electrolyte imbalance in the body, nausea, fatigue, confusion, seizures and in extreme cases death.
If you aspire to take part in longer endurance events, or have had issues with over or under-hydration in the past, then I would advise you to sek the advice of an experienced coach or personal trainer when it comes to your hydration and nutrition strategy. The advice which I am giving here is aimed squarely at the regular gym goer or casual exerciser, not endurance athletes for whom a different set of guidelines and issues apply. As somebody who lived and raced long distance endurance events in South Florida for many years, I could write a whole other post on the subject but will save that for another day.
So, back to the original question…what should people drink during an exercise class? I am going to be bold and say that if your class lasts for less than 60-90 minutes, the best thing you can consume is simply plain water. If you are exercising at higher intensities or for longer than that, it makes sense to include some form of electrolyte/calorie replacement drinks.
You will find a selection to choose from in the supermarket, but almost without exception you would do better to go to a proper sports nutrition website and do some research on the quality of what is available. From an economic standpoint, it is much cheaper to buy powders and mix your own drink, or you could even experiment with making your own from natural ingredients.
For the regular gym goer who attends classes, not only are most of the RTD (ready to drink) products loaded with chemicals and preservatives, but they will give you an often unnecessary sugar overload. I made a quick scan of some popular sports drinks, and this is what I found.
| BRAND | CALORIES | CARBS / SUGAR |
| Lucozade Energy Original (380ml) | 266 | 65g |
| Lucozade Sport Cherry (500ml) | 135 | 32g of which sugar 14g |
| Powerade Cherry (500ml) | 85 | 19.5g (100% sugar) |
| Red Bull Energy (330ml) | 148 | 36g (100% sugar) |
| Relentless Energy Drink (500ml) | 230 | 52g (100% sugar) |
In case you are not sure, a teaspoon of sugar is roughly 4g, meaning that some of these drinks have 16 teaspoons of sugar in them! If you have read anything else on my website, you probably know that controlling blood sugar is one of the big keys to changing body composition (the amount of fat on your body).
The touted calorie expenditure during exercise classes and the readouts on most CV machines are misleading, and often significantly exaggerated. For the regular gym goer looking for body composition changes, casually sipping on a sports drink whilst attending a class or two will undo most of your good work.
Add to that the long list of nasty sounding chemicals listed in the ingredients of many sports drinks (acacia gum, glycerol esters of wood rosins, sucralose, acesulfame K, glucuronolactone, inositol, phenylalanine, pantothenic acid), and you have to ask if any of those really sound like something which should be going into your body? It is far better to drink water whilst you exercise, and then refuel your body with ‘real food’.
So we come full circle. My advice to those who take exercise classes is simple; drink a regular sports bottle full of water during a 45-60 minute class. Make sure that you are adequately hydrated before you begin the class, and monitor your urine output afterwards to make sure that you stay that way. Save the money which you would otherwise spend on that chemical junk to improve your diet by including more fruit, vegetables and lean protein.
As always, please add your questions and comments below on the blog, and I will do my best to answer them.
