Sports & Electrolytes: Magnesium, Potassium & Co. in Balance

Which electrolytes matter during exercise? Through sweat you lose mainly sodium, plus smaller amounts of potassium, magnesium and calcium. During long, intense or sweaty sessions, a targeted intake of these minerals can make sense, while short, moderate activity is usually covered by water and a balanced diet.

Do you know that feeling when your T-shirt shows white salt rims after a long summer run? That is no coincidence but lost sodium, and with it other minerals leave the body too. Precisely these dissolved minerals are the "electrolytes" that keep muscles, nerves and the water balance running. This guide shows you which of them count for you as an athlete, which authorised functions they have and when reaching for a targeted intake is really worth it.

The key points at a glance

• Electrolytes are dissolved minerals, above all sodium, potassium, magnesium and calcium.
• Magnesium contributes to normal muscle function, to electrolyte balance and to the reduction of tiredness.
• Potassium contributes to normal muscle function, to the function of the nervous system and to normal blood pressure.
• During intense sweating, a targeted intake can make sense; for short activity, water and diet are usually enough.
• For endurance athletes, iron is an additional topic (oxygen transport, less tiredness).

What are electrolytes, and what do they do in the body?

Electrolytes are minerals that are present in the body dissolved as electrically charged particles (ions). This charge is the crucial point: it steers the water balance between the cellular compartments, enables signal transmission along the nerves and the interplay of tension and relaxation in the muscle. With every muscle contraction, sodium, potassium, calcium and magnesium work together in finely tuned coordination. When sweating, you lose mainly sodium and, in smaller amounts, potassium, magnesium and calcium. If this loss is not compensated during long exertion, the finely balanced equilibrium starts to waver.

How much you actually lose is, by the way, very individual. Some people sweat noticeably more and more saltily than others, recognisable by white salt rims on the skin or clothing after training. The ambient temperature, the training intensity and your acclimatisation also play a major role. This explains why blanket recommendations are difficult here: a two-hour run at 30 degrees places completely different demands than a half-hour round in autumn. That is exactly why it is worth aligning your own needs with the length, intensity and heat of the respective session rather than following rigid rules.

The most important electrolytes for athletes

For endurance athletes, iron is also a topic: it contributes to normal oxygen transport in the body and to the reduction of tiredness and fatigue - more in the guide Recognising and preventing iron deficiency and in Nutrients for runners & endurance.

What research is investigating

That electrolytes are lost through sweating and that sodium is the largest loss by quantity is well-established basic knowledge. Beyond this, active research looks at how strongly sweat composition varies individually (some people are "salty sweaters" with a noticeably higher sodium loss), from what duration and intensity of exertion compensation brings measurable benefits, and how electrolyte intake can be timed optimally. For practice, the line stays clear: the longer, more intense and sweatier the session, the more worthwhile a targeted compensation becomes.

Magnesium and potassium in detail

Magnesium - the muscle all-rounder

Magnesium is involved in more than 300 enzymatic reactions and, in the muscle cell, is the counterpart to calcium - so it is directly involved in the switch between tension and release. Heavy sweating can increase the need. Which form is suitable is clarified by Which magnesium is the best?; the comparison of the two most popular forms is in Magnesium bisglycinate or citrate. How quickly the supply builds up is put into context by How long until magnesium works?.

Potassium - the counterpart to sodium

Potassium works inside the cell as the counterpart to the sodium outside - this sodium-potassium gradient is the basis of every signal transmission. Potassium contributes to normal muscle function, to the function of the nervous system and to normal blood pressure. Good sources are bananas, potatoes, pulses and green vegetables. How to cover your needs through diet is shown by Covering potassium needs through diet; the distinction from magnesium is clarified by Magnesium vs. potassium.

Sodium and calcium - the quiet team players

Magnesium and potassium get a lot of attention, yet two further electrolytes deserve notice. Sodium is the largest loss by quantity in sweat and at the same time the electrolyte that decisively controls how well fluid is retained in the body. Anyone who drinks only water without sodium during long exertion can even dilute the salt balance further - which is why sensible sports drinks always contain some sodium. Calcium, in turn, contributes to normal muscle function and works in the muscle cell as the direct counterpart to magnesium: calcium triggers the contraction, magnesium the relaxation. This interplay shows why electrolytes should always be thought of as a team and not in isolation.

Mix electrolytes yourself - or use a ready-made complex?

A simple electrolyte drink can in principle be prepared yourself: water, a pinch of salt (sodium), some juice (potassium, e.g. from orange or apple juice) and optionally a magnesium source. The advantage: full control over the ingredients. The disadvantage: the amounts are hard to hit exactly, and the balance of minerals easily becomes uneven. A ready-made electrolyte complex takes this arithmetic off your hands, because it bundles the relevant minerals in coordinated amounts - particularly practical before or during longer sessions. Both approaches are legitimate; the choice depends on how much effort you want to put in and how plannable your intake should be.

Water and electrolytes belong together

A frequently overlooked point: drinking a lot alone is not automatically the best strategy during long exertion. Anyone who drinks only pure water for hours while sweating heavily does replace the fluid, but not the lost minerals - above all sodium. This can shift the fine balance even further. It therefore makes sense, during long or hot sessions, to think of fluid and electrolytes together rather than separating the two. For short sessions this is no issue; here water is perfectly enough. But the longer and sweatier it gets, the more important the combination becomes - that is the core idea of every well-thought-out sports drink.

When does supplementation make sense?

Not every training session needs an electrolyte drink. As a rough guide:

• Short, moderate activity (up to ~60 min., little sweat): water and a balanced diet are usually enough.
• Long, intense or very sweaty sessions (endurance sport, heat, exertion lasting several hours): an electrolyte drink can help to make up for what was lost.
• Heat & summer: the loss also rises outside of sport - see Electrolytes in summer & heat.

Around training, it is also worth looking at the timing of intake - see Supplements before or after exercise and, for occasional exercisers, Nutrients for occasional athletes. Anyone who regularly runs long distances will find further starting points in Nutrients for runners & endurance, and strength athletes in Nutrients for strength training & muscle building.

Covering electrolytes through diet

For most everyday and recreational athletes, the best electrolyte source is the plate. A colourful, mineral-rich diet already covers the need well in many cases:

Only when the exertion becomes long and sweaty does the additional reach for a targeted compensation pay off. How to cover potassium in particular through diet is shown by Covering potassium needs through diet.

Honestly put into context: what is certain and what is not

It is certain that sweating leads to electrolyte losses and that magnesium and potassium have clearly authorised functions for muscles and nerves. Part of being honest: during short, moderate activity an electrolyte drink is usually not needed - here water and diet are enough. Electrolytes are not a performance booster at the push of a button, but compensate for what is lost. Those who regularly train for very long periods or in great heat benefit most. In the case of persistent exhaustion or muscle issues, please have it checked medically.

Matching products from Scheunengut

You will find the important minerals individually in the categories Magnesium and Potassium, and for endurance athletes additionally Iron. An all-round view for active people is given by Sport & Fitness. Further reading to match: Energy: magnesium, iron & B vitamins, Nutrients for recovery after sport and Nutrients for the muscles. All products are lab-tested and made in Germany.

Frequently asked questions (FAQ)

Which electrolytes do you lose most during sport?

By quantity, most is lost through sweat as sodium, plus smaller amounts of potassium, magnesium and calcium. How large the loss is varies greatly from person to person and depends on the amount of sweat, the intensity and the heat.

Do you always need an electrolyte drink during sport?

No. During short, moderate activity with little sweat, water and a balanced diet are usually enough. An electrolyte drink is worthwhile above all during long, intense or very sweaty sessions as well as in the heat, to make up for what was lost.

Why are magnesium and potassium important for athletes?

Both are involved in muscle and nerve function: magnesium contributes to normal muscle function, to electrolyte balance and to the reduction of tiredness, potassium to normal muscle and nerve function as well as to normal blood pressure. Heavy sweating can increase the need.

Is water alone enough during long endurance sport?

During long, sweaty exertion, pure water can fall short, because minerals are lost too. A drink with electrolytes helps to make up for sodium, potassium and magnesium. For endurance athletes, a good iron supply is also relevant.