- Electrolytes in the body are most often called mineral substances in the form of ions.
- During physical activity, they are lost due to sweating.
- Electrolytes can be replenished from the diet, mineral waters or sports supplements.
I'm sure you've experienced having salt maps on your workout shirt after an intense session, so much so that you could find a forgotten medieval treasure based on them. The next time this happens, you'll have evidence that your body lost a lot of electrolytes during your workout. Just to be sure, you can even taste the salty residue to confirm your hypothesis.
What are electrolytes, and how do you deal with their loss during physical activity?
What is the relationship between electrolytes and minerals?
Electrolytes in the body are most often minerals that are present in the body in ionic form. Because of this, they always have a charge and can transmit electrical signals. However, not all minerals in the human body are found in this form. Let's look at calcium, for example:
- Non‑ionic form: most of the calcium in the body is found in the mineralised parts of bones and teeth in the form of hydroxyapatite. Here, calcium does not occur in the ionic form.
- Ionic form: approximately 1% of calcium is found in cells and serves, among other things, to initiate muscle contraction. In this case, calcium (calcium cations) is viewed as an electrolyte.
Why are electrolytes lost during sports performance?
During training or other physical activity, your muscles are working at full capacity. While they perform useful work, they also generate a lot of waste heat that must be dissipated. Otherwise, it could "cook" you alive.
Fortunately, our bodies are full of water, which is also the cooling medium of choice for even the smartest engineers, including those who design nuclear power plants. One litre of evaporated water removes about 580 kcal at human body temperature, making it a pretty efficient cooling system.
But how do electrolytes relate to all of this?
Water in the body always contains a significant amount of electrolytes, and the water excreted through sweating is no different. Although the body attempts to reabsorb minerals in various ways, it can never fully recover them. Electrolyte losses are, therefore, a necessary part of sweating that you cannot avoid.
You can lose up to 2 grams of sodium per hour of training
How much electrolytes you lose during physical exercise is highly individual, so definitely don't expect a simple one‑size‑fits‑all calculation. Let's talk about this in a little more detail.
- First and foremost, of course, it depends on how much you sweat out during a workout. In an hour of intense training, you produce about 0.5‑2.0litres of sweat on average, but unless you're training in the heat, you're looking at the lower end of this range.
The concentration of sodium in sweat also varies quite a bit anddepends on your hydration and individual differences, among other things. When Lindsay Baker from Oakland, USA, addressed this in her publication, she talked about 10‑90mmol of sodium per 1 litre of sweat, which equates to about 0.2‑2.1g of sodium per 1 litre of sweat.
Other factors that affect electrolyte loss include gender, weight and acclimatisation to the environment. It has been found that after acclimatisation to a hot environment, electrolyte loss can be reduced by more than 50%.
However, sodium is not the only important electrolyte in sweat. If you've ever looked at the composition of electrolyte drinks, you've probably also come across potassium, magnesium, chlorine and calcium. They're not just there for decoration; they are also lost from the body through sweat:
- Potassium (in the form of K+) is present in sweat at a concentration of about 95mg per 1 litre of sweat (loss in about 1 hour of training).
- Magnesium (in the form of Mg2+) is present in sweat at a concentration of about 19mg per 1 litre of sweat (loss in about 1 hour of training).
- Calcium (in the form of Ca2+) occurs in sweat at a concentration of about 40mg per 1 litre of sweat (loss in about 1 hour of training).
- Chlorine (in the form of Cl-) is present in sweat at a concentration of about 1065mg per 1 litre of sweat (loss in about 1 hour of training).
Electrolyte replenishment during exercise: when should you consider it?
If you look at the above approximate electrolyte losses during exercise, you'll see that, with the exception of sodium, it's not that bad, and even strenuous sports training shouldn't compromise your stores. It's a different story with sodium, where with very demanding workouts, the losses of this element can be so great that it pays to keep this in mind and supplement sodium appropriately.
You have a few ways to tackle electrolyte replenishment:
- Electolyte drink during training.One common option is to buy a good‑quality sprorts drink that contains all the electrolytes mentioned above. Electrolyte drinks also contain simple sugars to help with energy replenishment during longer workouts or races.
- Mineral waters. Mineral waters are another effective way to replenish electrolytes. Choose wisely, though, as each "mineral water" contains a slightly different proportion of electrolytes.
- Common foods. You can also get sodium, along with other electrolytes, from common foods at almost any time of the day. Sodium is easy to get from baked goods and salty foods; apples and bananas are rich sources of potassium; magnesium is found in pumpkin seeds, and calcium is found in dairy products.
Don't be tempted by manufacturers' claims that you need an electrolyte drink for every workout. If you have a proper diet and your workouts are not extreme, you probably don't need more than adequate amounts of pure water to exercise.
But if you have very demanding workouts, play sports in the heat, or are preparing for physically demanding races, definitely consider including a quality electrolyte drink. For example, in a study on athletes who completed a challenging triathlon, it was found that taking salt capsules reduced fluid loss during exercise and improved race times.
Hypotonic Sports Drink without Sugar
Bottom line
Electrolytes are minerals that are most often found in the human body in the form of ions. The most important are sodium, potassium, magnesium, and calcium cations (positively charged) and chloride anions (negatively charged). Electrolytes are naturally lost through sweating. Sodium losses are greatest (about 800mg per litre of sweat, on average), followed by potassium (95mg per litre of sweat), calcium (40mg per litre of sweat), and magnesium (19mg per litre of sweat).
Electrolytes lost during athletic performance should be replenished. Focus on a diet rich in these mineral elements, and in the case of large losses (during intense training or racing), you can include high‑quality ionic drinks, which are also a source of fast carbohydrates that have a positive effect on sports performance.
