What does sodium do?
Sodium plays a role in fluid balance, water absorption, regulation of blood pressure, and muscle contraction. This is something that you certainly don’t want to get wrong. Thankfully, the body has tight hormonal control mechanisms that take care of variations in your sodium intake. Exercise puts extra demands on these systems. Let’s take a look at how sodium intake can impact exercise.
Does sodium influence muscle cramping?
Sodium is involved in muscle contractions and many believe that sodium losses may be causing muscle cramps. Unfortunately, exercise-induced muscle cramping is very hard to study. There are too many contributing factors. Here are just some of them.
- Warm vs cold climate
- Condition of the muscle
- Intensity and length of the exercise session
- Hydration status
- Electrolyte status
We know that cramps happen more often in warm climates and later into the exercise when chances for dehydration and sodium losses are higher. But we currently don’t have sufficient evidence to say how big of a role sodium plays – if any.
Does sodium increase water absorption?
It is well-established that adding a small amount of glucose to water significantly helps your body absorb it. That’s why sports drinks are sweet and typically contain around 6 % of sugar. Something similar is claimed about sodium. Unfortunately, studies show that even though sodium can increase absorption, the effect is very small, virtually insignificant. However, sodium can help with hydration in a different way.
Sodium makes a drink tastier and you thirstier
A small amount of sodium can help you stay hydrated by making a drink taste better. Sodium also influences your thirst. It increases osmolality, the concentration of minerals in the blood, which prompts a thirst response. Both of these effects make it more likely you will drink more which will in itself help you stay hydrated.
So how much sodium should you consume? You only need a small amount, 400-500 mg sodium per litre of water will make a drink more palatable. If you go over 1,000 mg per litre, you will achieve the opposite and make the drink taste disgusting. It’s also good to keep in mind that other sodium-containing supplements you take during exercise count too. For example, if you take salt tablets, they will increase your osmolality way too much and the effect of a carefully balanced sports drink will be lost.
Can sodium help with water retention?
Sodium is key in storing the water you drink in the body. In theory, increasing salt and water intake hours before a race in a hot climate could improve hydration status at the start. Can this improve performance and influence an outcome of a race? And how about replenishing sodium that you lose while sweating? Can that help you perform better? We will take a look at that in the rest of this series.