Magnesium is not a glamorous topic. It does not have the performance narrative of creatine or the recognition of protein. But it sits at the centre of several physiological processes that directly determine how well you train, recover, and sleep.
And the majority of people who train regularly are likely suboptimal in it.
Why Athletes Are Especially at Risk
Magnesium is lost through sweat and urine. The harder and more frequently you train, the higher your losses. Simultaneously, physical and psychological stress increases magnesium excretion via cortisol. The people with the greatest demand are therefore the ones losing the most.
Dietary sources — dark leafy vegetables, nuts, seeds, whole grains — are frequently underconsumed in higher-protein, lower-carbohydrate athletic diets. The result is a consistent functional deficit that rarely reaches clinical deficiency but meaningfully impairs performance and recovery.
What Suboptimal Magnesium Looks Like
Impaired sleep quality — specifically reduced slow-wave sleep and increased night-time waking. Increased muscle cramp frequency. Elevated resting heart rate. Reduced insulin sensitivity. Higher anxiety and cognitive arousal. These symptoms are common in hard-training individuals and routinely attributed to overtraining or stress when the proximate cause may be nutritional.
Not All Forms Are Equal
Magnesium oxide has poor bioavailability and primarily acts as a laxative at supplemental doses. Magnesium glycinate — magnesium bound to glycine — has superior absorption, minimal gastrointestinal effects, and benefits from glycine’s independent role in sleep quality and connective tissue synthesis. Magnesium malate is well-absorbed and may have additional benefit for energy metabolism via the malate component’s role in the citric acid cycle.
How to Supplement
300-400mg of elemental magnesium daily from a high-bioavailability form. Evening dosing to support sleep. Taken consistently, not reactively. The benefits are cumulative — magnesium repletion takes weeks, not days.
It is not the most exciting intervention. It is among the most reliable.