Fluid balance and electrolytes during cycling
The body consists of 50-70% water, and fluid balance has a major impact on your performance on the bike. If you ride intensely – especially in hot environments – the fluid loss through sweat can be more than 2 liters per hour. At the same time, you lose minerals (electrolytes), where sodium in particular plays a central role in regulating fluid balance. Sodium is part of sodium chloride, which we know as common table salt.
There are large individual differences in how much we sweat and how much sodium the body excretes. You can weigh yourself before and after a hard workout (remember to subtract fluid intake) to find your fluid loss per hour. The sodium content in sweat typically varies between 0.5–1.3 g per liter, but a good average is about 1 g sodium per liter of sweat. This means that it is not enough to just drink water on longer bike rides – electrolytes also need to be replaced.
How much should you drink during cycling?
Using electrolyte or salt mixtures is essential to maintain fluid balance during exercise. You should adjust your fluid intake to your sweat loss – but be aware that the body can absorb a maximum of 1–1.2 liters of fluid per hour. You should therefore not drink more than this, even if your fluid loss is higher.
After the ride – restore fluid and salt balance
There are large individual differences in how much we each sweat and how much sodium the body excretes. You can weigh yourself before and after a hard workout (where fluid intake is subtracted) to find out how many L/h you sweat. But it is not possible to determine the sodium content from a simple test. It can vary by about 0.5-1.3g sodium/L sweat. A good guess is therefore that we lose about 1 g sodium/L sweat. And this must be replaced equally with fluid. In other words, it is not enough to just drink water on long bike rides.
Using an electrolyte/salt mixture is therefore essential to regulate fluid balance.
How much fluid and electrolytes should you consume?
You should not drink more than you lose in sweat. BUT PLEASE NOTE:
The body can only absorb a maximum of 1-1.2 L of fluid per hour, so you should not drink more, even if your sweat loss is greater.
If you sweat more than you consume, you should drink fluids with electrolytes after exercise. You should do this continuously with 1.2-1.5 liters of fluid with 1 g of sodium/L for each kilogram lost during exercise.
Salt vs sodium – what should you be aware of?
Most people get some salt (and therefore sodium) through their diet, so some of the fluid after exercise can be plain water. Be aware that “salt” is not the same as sodium, as table salt also contains chloride. Therefore, use the following formula: sodium content = salt content × 0.4