Everyone talks about electrolytes and rehydration after exercise. But what do these electrolytes do and why do we need them?

Electrolytes are minerals in your blood and other body fluids that carry an electric charge – in other words, they conduct electrical impulses. Electrolytes you may have heard of include sodium, calcium, chloride, magnesium and potassium.

These minerals must be present in the human body in proper concentrations as they influence important aspects of the way your body functions, such as maintaining fluid balance, and enabling muscle contraction and nerve activity. That’s why electrolytes play an integral role in athletic performance, particularly during intense or prolonged exercise that lasts longer than one hour, when electrolytes are lost through your sweat.

So what exactly is in sweat? About 99 per cent of sweat is water, along with the electrolytes I’ve already mentioned, in varying amounts.


When you’re doing intense or prolonged exercise, the most common electrolytes that get out of balance are sodium and potassium. So when you’re rehydrating after exercise, you need to get enough sodium to fully restore fluid balance.

The sodium in sports drinks not only increases fluid absorption and retention, it also encourages you to drink more fluids by driving the mechanism that makes you thirsty. And although sodium can be replaced through food or by adding salt to food, electrolyte supplements or sports drinks provide a convenient way to rapidly restore fluids and electrolytes in a more targeted approach.

Potassium, meanwhile, has a similar role to sodium as far as fluid balance goes, but it plays more of a key role in maintaining water balance inside the cells of your body, where sodium regulates fluids outside of the cells of your body. Potassium is also well known for maintaining a healthy amount of blood for your body to function well and also for effective blood pressure. For example, if you have a high level of fluid in your system, potassium allows any excess water to be excreted through the urine to help restore the optimal water level in your body.

Magnesium plays a key role in energy metabolism by helping cells utilise sugars and oxygen for the working muscles. Magnesium depletion may reduce physical performance and reduce exercise capacity, and is associated with muscle twitching, cramps and muscle weakness. Therefore the addition of magnesium to sports drinks is beneficial to assist with sustained muscle contraction, and therefore optimal performance during exercise.

Kathleen Alleaume


Kathleen Alleaume is an accredited exercise physiologist and nutritionist and founder of The Right Balance