Water is enough for most workouts – but when training gets longer, hotter or more intense, electrolytes can make a meaningful difference. Dietitian, Dr Paul McArdle RD MBDA, explains how when to use each can help you stay hydrated, perform better and avoid common pitfalls
Spend any time in a gym and you’ll hear the same debate: do you really need electrolytes, or is water enough? The answer is simple. Both have their place; it’s about using the right tool for the job.
When you exercise, your body cools itself by sweating. Sweat is mostly water, but it also contains electrolytes like sodium, which help regulate fluid balance, nerve function and muscle contraction. For most everyday workouts, sodium losses are relatively small.
That’s why, for most people, water does the job perfectly well. If your session is under 60–90 minutes, moderate in intensity, in cooler conditions, and followed by a normal meal, you’re unlikely to need anything more. Your body can replace what’s lost through normal eating and drinking.
Where things change is when training becomes longer, hotter, or more demanding. Endurance sessions increase both fluid and sodium losses, and in these situations, drinks containing electrolytes can help you maintain fluid balance over time. The same goes for exercising in the heat, where higher sweat rates mean greater losses. Some people also naturally lose more sodium in their sweat and may benefit more from electrolytes.
Electrolytes also come into their own when rapid rehydration is needed, for example during tournaments or when training more than once a day. Sodium helps your body retain more of the fluid you drink, compared to water alone.
It’s worth remembering that more isn’t always better. Drinking large amounts of water during prolonged exercise without replacing electrolytes can dilute sodium levels in the blood, leading to hyponatraemia. It’s rare, but potentially serious. For most people, drinking to thirst is a sensible approach, though longer or hotter events may need a bit more planning.
Performance is where things often get misunderstood. When sports drinks improve endurance performance, it’s usually because they contain carbohydrates, which provide energy, not just electrolytes. Electrolytes support hydration, but on their own they don’t directly improve performance.
Get the balance right
Alongside traditional sports drinks, there are a wide range of low-and no-sugar options, many using non-sugar sweeteners like aspartame, sucralose or stevia. They can be just as effective at hydration and can make drinks more appealing than plain water, which may help some people stay better hydrated. Studies show they are safe and don’t increase blood glucose, insulin levels or appetite.
Some low- and no-sugar drinks also contain electrolytes and can support hydration in the same situations. The key difference is that they don’t provide energy. So, if fuelling is part of the goal, carbohydrate intake still matters.
In practice, it’s less about choosing water or electrolytes, and more about matching your approach to your training. Water is ideal for most everyday sessions.
Electrolytes become more useful as exercise gets longer, hotter or more demanding. And if you need energy as well as hydration, drinks containing carbohydrate may be the better option.
Get that balance right, and you’ll support both performance and recovery without overthinking it.
• For more information on the use of non-sugar sweeteners, visit the British Soft Drinks Association
