Unexplained fatigue after a workout, muscle cramps during exertion, restless nights despite planned recovery: these signs are often trivialized, when they can indicate a magnesium deficiency. This essential mineral is involved in over 300 enzymatic reactions in the body, and athletes are among the profiles most exposed to a deficit. Understanding the mechanisms of this deficiency, knowing how to recognize it and acting effectively are key steps to maintaining performance and overall balance.

• Athletes are more susceptible to magnesium deficiency due to losses through perspiration and increased energy demands.
• The first signs of magnesium deficiency include persistent fatigue, muscle cramps, irritability, and sleep disturbances.
• A varied diet (legumes, nuts, whole grains, green vegetables) forms the basis of a good magnesium intake, often insufficient on its own for athletes.
• Magnesium bisglycinate is the best absorbed and best tolerated form for effective supplementation without digestive discomfort.
• A one-to-three-month course, with 282 mg of magnesium per day combined with vitamin B6, helps correct a deficit and sustainably support performance and recovery.

Magnesium deficiency is often silent, but its effects on performance and recovery are well documented. Before examining how to identify and correct it, it is useful to understand what it represents physiologically, and why athletes are particularly exposed to it.

Magnesium is a mineral involved in a considerable number of biological functions. It directly participates in cellular energy production, muscle contraction and relaxation, nerve transmission, and protein synthesis. It also contributes to electrolyte balance, maintaining normal bone function, and regulating the nervous system.

Its role as an enzymatic cofactor makes it a central player in metabolism. Without sufficient magnesium intake, many physiological processes slow down or become unbalanced. The body does not synthesize it: it must be supplied through diet, and if necessary, through appropriate supplementation.

Athletes have a higher risk of magnesium deficiency for several cumulative reasons. Firstly, physical exertion increases magnesium needs, particularly for ATP production (the cell's energy molecule) and to ensure efficient muscle contraction. Secondly, perspiration is a direct and significant route of loss, difficult to compensate for with an ordinary diet.

Added to this is a nutritional reality often overlooked: modern diets, even among athletes who are careful about their food intake, struggle to meet magnesium needs. Processed foods, poor in micronutrients, have largely replaced natural sources of this mineral. As a result, magnesium deficiency is one of the most common micronutrient deficiencies in France, across all profiles.

Reference Nutrient Values (RNVs) set magnesium needs at approximately 375 mg per day for an adult. For athletes, this threshold can be significantly higher depending on the intensity and frequency of training, with some experts estimating needs up to 400 to 500 mg per day during intense training periods.

These needs are not always met by diet alone, even a balanced one. This is why a magnesium supplement can be a relevant intake to maintain optimal levels, especially during loading phases or periods of increased physical and mental stress.

A magnesium deficiency does not always manifest itself in an obvious way. The signs are often diffuse, progressive, and easily attributed to fatigue or overwork. However, they follow a coherent physiological logic, and recognizing them allows action to be taken before performance suffers.

Fatigue is one of the first signs of magnesium deficiency. When reserves are depleted, ATP production in the mitochondria is altered. Cells have less available energy, which results in persistent physical and mental fatigue, even after a sufficient night's sleep.

This fatigue differs from ordinary post-effort fatigue: it is more diffuse, less correlated with training intensity, and does not disappear with usual rest. For an athlete, this can manifest as a feeling of heavy legs, difficulty recovering between sessions, or an unexplained drop in motivation.

Muscle cramps are among the most frequently associated signs of magnesium deficiency. The mineral plays a key role in regulating calcium exchanges at the muscle fiber level. A deficiency disrupts this balance: muscles have difficulty relaxing properly after contraction, which causes cramps, spasms, and even contractures. 

These cramps often occur at night or during exertion, and can affect the calves, feet, thighs, or even hands. They represent a functional warning sign not to be ignored in a regular athlete. 

Magnesium is directly involved in the regulation of the nervous system. A lack of magnesium can manifest as increased sensitivity to stress, unusual irritability, difficulty concentrating, or difficulty decompressing after effort. These symptoms of magnesium deficiency are often underestimated because they are associated with general fatigue or overwork.

Magnesium contributes to sleep quality through several documented mechanisms: antagonism of NMDA receptors and activation of the GABAergic system, which promote nocturnal neuromuscular relaxation. Preliminary data, mainly animal, also suggest an influence on melatonin synthesis, but this link remains to be confirmed in humans. A deficiency can lead to difficulty falling asleep, nocturnal awakenings, or unrefreshing sleep, thus directly compromising the quality of recovery.

A prolonged lack of magnesium eventually directly affects performance. The efficiency of muscle contraction decreases, resistance to effort is reduced, and recovery times are extended. Muscle fatigue also translates into greater sensitivity to muscle soreness and post-effort pain.

At this stage, the signs of magnesium deficiency are no longer isolated: fatigue, cramps, sleep disturbances and decreased performance accumulate and feed into each other, creating a vicious cycle for athletic progression.

Magnesium deficiency is rarely the result of a single cause. It most often results from a combination of dietary, physiological, and behavioral factors that reinforce each other, and of which athletes frequently experience several simultaneously. 

The primary cause of magnesium deficiency is nutritional. Magnesium-rich foods, such as legumes, nuts, whole grains, and green leafy vegetables, are often consumed in insufficient quantities in contemporary diets. Ultra-processed, refined, and fiber-poor foods make up a growing portion of caloric intake, without a significant contribution of magnesium.

For some athletes, restrictive diets (cutting, low-calorie diets) further amplify this imbalance by reducing the diversity and micronutrient density of dietary intake.

Sweating induced by physical exertion leads to magnesium loss, and exertion increases magnesium excretion through urine. These losses add to the increased needs generated by the exertion itself, creating a double deficit mechanism that is difficult to compensate for through diet alone.

Endurance athletes, indoor sports practitioners, and athletes training at altitude are particularly affected by this phenomenon. Muscle recovery is further compromised when losses are not compensated.

Chronic stress, whether physical or psychological, increases magnesium needs and accelerates its urinary elimination. Indeed, cortisol, the stress hormone, promotes renal magnesium leakage. In turn, a magnesium deficit worsens the stress response by amplifying the reactivity of the nervous system: this is a well-documented vicious cycle.

Overtraining, common in dedicated athletes without adequate periodization, combines both mechanisms: losses through perspiration and chronic activation of the stress axis. Magnesium deficiency then becomes both a cause and a consequence of physical overwork.

Certain individuals experience reduced intestinal absorption of magnesium due to functional digestive disorders (irritable bowel syndrome, chronic inflammatory bowel diseases, malabsorption). Excessive alcohol consumption, certain diuretic medications, or associated deficiencies (particularly vitamin D) can also reduce magnesium assimilation.

In these situations, even a correct dietary intake of magnesium is not enough to maintain optimal levels, which justifies supplementation in a highly bioavailable form.

Beyond preventing deficiencies, magnesium plays an active role in performance and recovery. Its effects are not limited to preventing cramps: it intervenes at every stage of the exertion-recovery cycle, from cellular energy yield to sleep quality. a

Magnesium is essential for proper muscle function. At the cellular level, it regulates calcium channels that control the contraction-relaxation alternation of muscle fibers. Optimal magnesium intake allows for precise and efficient muscle contraction, and especially complete relaxation between efforts.

Without this balance, muscle fibers remain in a state of partial tension, which increases the risk of cramps, strains, and premature fatigue. This mechanism explains why cramps are common in athletes who do not consume enough magnesium.

Magnesium is a cofactor for ATP synthase, the enzyme responsible for ATP production in the mitochondria. Without sufficient intake, the cell produces less available energy, which directly results in muscle fatigue and a decrease in exercise capacity.

Combined with vitamin B6, the formula targets two complementary mechanisms: magnesium contributes to normal energy metabolism and normal muscle function, while vitamin B6 contributes to the reduction of fatigue and the normal functioning of the nervous system. In vitro data suggest a direct interaction between the two nutrients, although clinical demonstration of this synergistic effect is not yet fully established.

Magnesium contributes to recovery through several mechanisms: reduction of residual muscle tension after exercise, support for protein synthesis for repairing damaged fibers, and contribution to better sleep quality, a crucial phase of regeneration.

Preliminary studies suggest that adequate magnesium status could help modulate the post-exercise inflammatory response, although available data remain insufficient to establish a causal link. These results highlight the importance of regular monitoring of intake in any recovery program.

The link between magnesium and stress management is well-documented. The mineral modulates the activity of the NMDA receptor (N-methyl-D-aspartate), involved in the stress response and neuronal plasticity. Sufficient intake helps to attenuate the reactivity of the nervous system to stressful stimuli, promotes relaxation, and improves sleep quality.

For an athlete, this is not just a matter of comfort: it is a variable directly linked to recovery capacity, training quality, and long-term progression.

Correcting a magnesium deficiency relies on two complementary levers: diet and supplementation. One without the other quickly reaches its limits, especially in an athlete whose needs are structurally higher than average.

The first step to correcting a magnesium deficiency is to optimize dietary intake. The magnesium-rich foods to prioritize are:

• Nuts and seeds: almonds (270 mg/100g), pumpkin seeds (535 mg/100g), cashews

• Legumes: black beans, lentils, chickpeas

• Whole grains: brown rice, oats, quinoa

• Green leafy vegetables: spinach, Swiss chard, kale

• Dark chocolate with more than 70% cocoa

• Fatty fish: mackerel, sardines

These magnesium-rich foods provide a solid foundation, but their bioavailable magnesium content varies depending on the cooking method, the presence of phytates (antinutrients that limit absorption), and the individual's digestive state. For an athlete with high needs, diet alone quickly reaches its limits.

Given increased needs and significant perspiration losses, supplements represent a practical and effective solution to address a deficiency. They provide precise, reproducible dosing adapted to the athlete's needs, without relying on the variability of dietary intake.

However, the effectiveness of supplementation largely depends on the chemical form of magnesium used, its dosage, and the presence or absence of cofactors that facilitate its absorption. Not all forms of magnesium are equal.

Organic forms of magnesium, such as magnesium bisglycinate and magnesium citrate, are significantly better absorbed by the intestine than inorganic forms (oxide, chloride). For athletes, the choice of form determines both the effectiveness of supplementation and its digestive comfort, especially during periods of intense training where transit may already be sensitive.

Magnesium bisglycinate is currently recognized as the reference form for athletes due to its high bioavailability and very good digestive tolerance. Magnesium citrate is an interesting alternative for rapid absorption, especially around exertion.

Not all forms of magnesium are equal in terms of absorption and digestive tolerance. The choice of chemical form is crucial for the actual effectiveness of supplementation, especially for athletes, whose digestive system may be weakened by exertion.

Magnesium bisglycinate is a chelated form: magnesium is bound to two glycine molecules, an amino acid naturally present in the body. This bond protects magnesium from degradation in the stomach and facilitates its active transport across the intestinal wall, significantly improving its absorption rate.

Unlike inorganic forms, magnesium bisglycinate does not cause an osmotic effect in the intestine, which eliminates the risk of laxative effects often encountered with other forms. This is why this form is primarily recommended for athletes seeking effective and comfortable daily supplementation.

Impulse Nutrition's Magnesium Bisglycinate provides 300 mg of magnesium daily in bisglycinate form, combined with 1.12 mg of vitamin B6, representing 75% and 80% respectively of the reference nutritional values. The Impulse Nutrition formula, developed by a pharmacist specialized in product innovation, is designed to maximize absorption and limit any digestive discomfort. Made in France, in vegetable capsules, it easily integrates into a recovery routine.

Magnesium citrate is another well-absorbed organic form, with a bioavailability profile slightly lower than bisglycinate but significantly higher than inorganic forms. Its high solubility makes it an interesting option for rapid absorption, for example, around exertion or during periods of acute deficit to be quickly filled.

On the other hand, magnesium citrate can have a slight laxative effect at high doses, especially in individuals with sensitive digestive systems. It remains a valid alternative for athletes who don't always tolerate bisglycinate well, even if the latter is generally better tolerated.

Marine magnesium is extracted from seawater and primarily comes in the form of magnesium oxide and hydroxide. Although naturally sourced, this type of magnesium has significantly lower bioavailability than organic forms. A large portion of ingested magnesium is not absorbed and exerts an osmotic effect in the intestine, which can cause digestive issues.

Magnesium oxide is the most concentrated form of elemental magnesium (around 60%), but this concentration does not compensate for its poor absorption. For athletes seeking real efficacy and optimal digestive comfort, organic forms like bisglycinate are largely preferable.

To explore all products available in the Energy and Vitality range, visit the complete Impulse Nutrition collection.

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