Magnesium for athletes: recognise deficiency, improve performance

Why magnesium matters for active people

Magnesium is involved in numerous metabolic processes—including normal muscle function, the nervous system and energy-yielding metabolism. Anyone who trains regularly should therefore ensure a reliable intake.

This does not mean that more magnesium automatically leads to better performance. The greatest benefit arises when an inadequate intake is identified and corrected sensibly.

Quick answer: magnesium for athletes is mainly about avoiding a low intake. Food comes first, supplements can help if your diet falls short, and there is no reliable evidence that extra magnesium speeds up muscle recovery or reliably prevents cramps in people who already get enough.

• Supports normal muscle function
• Contributes to normal energy-yielding metabolism
• Supports the normal function of the nervous system
• Is involved in many enzymatic reactions

• Volpe (2015) – Magnesium and the Athlete (https://pubmed.ncbi.nlm.nih.gov/26166051/) – Overview of magnesium functions and physical activity.

How to interpret possible signs

Muscle cramps, fatigue or poor sleep are often quickly attributed to magnesium deficiency. However, these symptoms are non-specific and can have many causes—from dehydration and high training loads to insufficient sleep.

• Recurring muscle cramps or twitching
• Persistent fatigue and unusual weakness
• Sleep problems and irritability
• Headaches or noticeably slow recovery

If symptoms occur frequently or are severe, you should seek medical advice rather than taking high-dose supplements on suspicion.

• NIH – Magnesium Fact Sheet (https://ods.od.nih.gov/factsheets/Magnesium-Consumer/) – Reference intakes, food sources, deficiency and safety.

Magnesium, muscles and energy

Magnesium is important for muscle contraction and relaxation, as well as for reactions that provide energy in cells. An adequate intake therefore supports normal function—but an additional performance boost from supplements has not been reliably demonstrated in people who already have an adequate intake.

• Muscles: involved in normal contraction and relaxation
• Energy: important for ATP-dependent reactions
• Nerves: supports signal transmission
• Recovery: part of a balanced mineral intake

The evidence on sleep is also less clear than advertising often suggests. A low magnesium status may be relevant, but this does not support general sleep claims for everyone.

• Newhouse & Finstad (2000) – Magnesium and exercise performance (https://pubmed.ncbi.nlm.nih.gov/10959930/) – Overview: supplementation does not reliably improve performance when intake is adequate.
• Arab et al. (2023) – Magnesium and sleep (https://pubmed.ncbi.nlm.nih.gov/35184264/) – Systematic assessment of the inconsistent evidence.

Magnesium for muscle recovery: what does the evidence say?

Magnesium is often marketed as a recovery mineral, but the evidence is more modest than the claims. Magnesium is involved in normal muscle function and energy-yielding metabolism, and a low magnesium intake can affect how muscles work. Reviews of magnesium and exercise conclude that supplementation is most likely to help people whose intake or status is low, while results in people with an adequate intake are mixed.

There is currently no reliable evidence that extra magnesium speeds up muscle repair or reduces soreness after hard training in people who already get enough.

• Most helpful: correcting a low intake, ideally through food first
• Uncertain: extra magnesium on top of an adequate diet
• Not established: faster muscle repair or less soreness from supplements in people with an adequate intake
• Support recovery first with sleep, enough protein, carbohydrates and fluids

Bottom line: magnesium is one part of recovery, not a shortcut. Check your intake before spending money on supplements.

• Zhang et al. (2017)—Can magnesium enhance exercise performance? (https://pubmed.ncbi.nlm.nih.gov/28846654/) – Review of studies on magnesium supplementation and exercise performance.
• Nielsen & Lukaski (2006)—Update on the relationship between magnesium and exercise (https://pubmed.ncbi.nlm.nih.gov/17172008/) – Review of magnesium status, exercise and supplementation.

Magnesium and muscle cramps: does it help athletes?

Magnesium is one of the most popular remedies for muscle cramps, yet the evidence is weak. A Cochrane review of randomised trials concluded that magnesium supplementation is unlikely to provide clinically meaningful cramp prevention in older adults, and that results for other groups are uncertain. Studies in athletes specifically are limited.

Exercise-related cramps are not fully understood. Fatigue, training intensity, heat and hydration status may all play a role.

• Do not rely on magnesium alone to prevent cramps
• Build up training volume gradually and allow enough rest
• Drink to thirst and replace fluids and electrolytes in long or hot sessions
• See a doctor if cramps are frequent, severe or occur at rest

Bottom line: magnesium is not a proven remedy for cramps. If you get cramps often, look at training load, hydration and your overall diet, and seek medical advice if they persist.

• Garrison et al. (2020)—Magnesium for skeletal muscle cramps (https://pubmed.ncbi.nlm.nih.gov/32956536/) – Cochrane review of randomised trials on magnesium and muscle cramps.

Requirements and magnesium-rich foods

As general guidance, the US National Institutes of Health recommends 400–420 mg of magnesium per day for adult men and 310–320 mg per day for adult women. This does not establish a special universal target for all athletes.

• Pumpkin and sunflower seeds
• Almonds, cashews and other nuts
• Oats and wholegrain products
• Beans, lentils and chickpeas
• Spinach and other green leafy vegetables

A handful of nuts, wholegrain products and a serving of pulses or green vegetables make it much easier to meet your needs in everyday life.

• NIH – Recommended magnesium intake (https://ods.od.nih.gov/factsheets/Magnesium-Consumer/) – Age- and sex-specific reference intakes.

Using supplements sensibly

If your diet does not meet your needs or a deficiency has been identified, a supplement may be useful. Pay attention to the actual amount of magnesium it contains, how well you tolerate it and possible interactions.

FitLine Restorate contains magnesium together with other minerals and can be incorporated into an evening routine.

• Start with a moderate amount
• Follow the current product label
• If you have a sensitive stomach, monitor your tolerance
• Consult a healthcare professional if you have a medical condition or take medication

Higher amounts of magnesium from food supplements can cause diarrhoea. More is therefore not automatically better.

Which magnesium form and when to take it

Magnesium supplements differ in the form of magnesium they contain. According to the US National Institutes of Health, well-soluble forms such as citrate, lactate or aspartate are absorbed more completely than magnesium oxide or sulfate. Which form suits you also depends on your stomach tolerance: higher doses of many forms can loosen stools.

There is no proven best time of day. Taking magnesium with a meal may reduce stomach upset, and many people prefer the evening because it fits an existing routine.

• The tolerable upper intake level for magnesium from supplements is 350 mg per day for adults; this does not apply to magnesium from food
• Check the label for the actual amount of magnesium, not just the weight of the compound
• Magnesium can interact with some medicines, such as certain antibiotics and bisphosphonates; ask a pharmacist or doctor
• People with kidney disease should only take magnesium supplements under medical supervision

Bottom line: choose a well-tolerated form, stay within the upper limit for supplements and put food first.

• NIH—Magnesium fact sheet (https://ods.od.nih.gov/factsheets/Magnesium-Consumer/) – Forms, absorption, upper limit and interactions.

Your next step

Magnesium is an essential nutrient, not a quick performance booster. First review your diet, fluid intake and overall recovery.

• Include magnesium-rich foods every day
• Do not rush to diagnose symptoms yourself
• Use supplements selectively rather than routinely
• Consider training, sleep and nutrition together

Learn more: Sports nutrition for muscle gain