For most amateur athletes, plain water is sufficient for hydration – high-sugar/high-sodium sports drinks just aren’t necessary, say researchers. By Jennifer Bowden.
Q: My teenage son eats a good diet and is involved in lots of different sports at school. But I’m concerned he drinks too many sports drinks. He takes them to school with lunch and drinks them with snacks at home. What do you think?
A: Sports drinks are specifically designed to improve fluid intake, hydration and performance by delivering precise levels of carbohydrates and sodium. But do amateur athletes need them? And are they good for our health when we’re not taking part in competitive sports?
Studies have shown that being well hydrated is beneficial to an athlete’s performance. Exercise leads to fluid losses, particularly through sweating, so hydration is needed to counteract this. If those lost fluids are not replaced, athletes can become dehydrated, and even a small degree of dehydration can affect their performance, worsening their endurance, power and strength. At its worst, dehydration can be a risk to life.
From a performance perspective, dehydration of 2-7 per cent of body mass has been shown to affect endurance in cycling time trials. And give a thought to our national cricketers, who play for hours under the blazing summer sun. A study of elite Sri Lankan cricketers found that 85 per cent of the fielders and bowlers were unable to maintain levels of speed and accuracy when dehydrated. Fielders suffered a sizeable reduction in speed and accuracy for overarm and sidearm throws, with sidearm-throwing accuracy dropping 22 per cent, for example. Bowlers’ speeds also fell, and their accuracy decreased by 20 per cent. The batsmen were mildly affected, running 2 per cent slower when completing three runs, and that could be the difference between a run-out and a safe run.
Elite athletes are trained to drink before they get thirsty, as this ensures they remain hydrated and maximise their performance, so sports drinks are a useful tool.
The drinks are specifically designed with 4-8 per cent carbohydrate content to promote optimal stomach emptying. If the carbohydrate concentration is higher, emptying is delayed, resulting in slower delivery of fluids and energy to the intestine, where it can be absorbed and used for refuelling and rehydrating while we exercise.
Sports drinks also contain sodium, a key electrolyte needed for the beverage to work. Sodium stimulates uptake of sugars and water from the small intestine into the body, which encourages rapid refuelling and rehydrating. It also stimulates thirst and replaces sodium lost through perspiration. Concentrations of sodium in drinks are specifically tailored to optimise this process.
The net result, then, is that a typical 750ml bottle of sports drink contains 10-12 teaspoons of sugar, 200mg of sodium and about 1000kJ of energy. This means it contains about the same amount of energy and sugar as a 500ml bottle of cola.
A 2018 review of sports drinks, published in the journal Nutrients, noted that although both amateur and professional athletes can experience dehydration, there is confusion about the need for sports drinks among these athletes. However, there is no confusion among sports science experts: they all agree water is sufficient for rehydration in most people.
Sports drinks should be used for what they are designed: to rehydrate and refuel when training or competing in high-intensity sports that last for 60 minutes or longer. Anything less than that intensity or duration and a bottle of plain water will suffice. Refuelling is not a concern when exercise intensity and duration are on the lower end of the physical activity scale.
Sports drinks are not suitable to enjoy with lunch, while watching television or while surfing the internet, as they provide few nutrients, add a considerable sugar load to the diet and may contribute to dental decay. They should be treated like any other sugar-sweetened drink (eg, soft drinks), and enjoyed only occasionally. Water and low-fat milk should be the mainstay for hydrating ourselves and our children.
