When an athlete chooses an energy gel, they usually look at the grams of carbohydrates, the sodium and perhaps the caffeine. Magnesium, if it appears at all, tends to be treated as a secondary data point — one more mineral in the ingredient list.
That is a mistake. And it is a costly one precisely in the moments when the body needs it most.
The reason is not just the amount of magnesium the gel contains. It is the form in which that magnesium is present. Because not all the magnesium you ingest reaches where it needs to go. And in the context of an intense physical effort, the gap between what is swallowed and what is actually absorbed can be the difference between finishing strong or not finishing at all.
Why magnesium is critical during physical effort
Magnesium is involved in more than 300 enzymatic reactions in the body. During endurance exercise, three of them are decisive:
ATP synthesis. Magnesium is an indispensable cofactor in the production of adenosine triphosphate — the energy currency of the cells. Without available magnesium, the energy machinery works less efficiently. In practical terms: more fatigue for the same pace.
Muscle contraction and relaxation. Magnesium acts as a natural antagonist of calcium in the regulation of the contraction-relaxation cycle of muscle fibers. When magnesium levels drop, calcium dominates and the muscle struggles to fully relax between contractions — which translates into cramps, muscle stiffness and a loss of efficiency in movement.
Neuromuscular transmission. Magnesium regulates the excitability of nerve membranes. Its deficiency during effort increases neuromuscular irritability, accelerating the onset of both central and peripheral fatigue.
On top of this, there is a problem specific to intense exercise: magnesium is actively lost through sweat. An athlete can lose between 4 and 8 mg of magnesium per liter of sweat. In a 3-4 hour effort with heavy sweating, that loss can be significant — and if it is not replenished effectively, the consequences on performance are measurable.
The key is in that last phrase: effectively. Because ingesting magnesium and absorbing magnesium are two very different things.
The bioavailability problem: what goes in is not what gets through
The bioavailability of a nutrient is the proportion of what is ingested that the body actually absorbs and can use. In the case of magnesium, this figure varies enormously depending on the chemical form in which it is presented.
The most common forms of magnesium in energy gels are carbonate, citrate and gluconate. All three are inorganic or low-complexity forms that share the same absorption mechanism: they need to ionize in the stomach — a process that depends on gastric pH — before they can cross the intestinal wall. During intense exercise, gastric pH changes, blood flow to the digestive system is reduced and intestinal motility is altered. Under these conditions, the absorption of inorganic forms of magnesium is compromised precisely when it is most needed.
There is another additional problem: inorganic forms of magnesium have an osmotic effect in the intestine that can cause digestive discomfort, especially when ingested during effort. Magnesium carbonate, in particular, is known for its laxative effect at moderate doses — an effect no mountain runner or cyclist wants to experience at kilometer 50.
Magnesium bisglycinate: a different solution
Magnesium bisglycinate is a chelated form: the mineral is chemically bonded to two molecules of glycine, a non-essential amino acid. This bond is not cosmetic or commercial — it fundamentally changes how the body processes the mineral.
Absorption via the amino-acid pathway. Because it is bound to glycine, bisglycinate does not need to ionize in the stomach. It is absorbed directly through the dipeptide and amino-acid transporters of the small intestine — a pathway independent of gastric pH, that works even when the digestive system is under the physiological stress of intense exercise.
No competition with other minerals. Inorganic forms compete with each other for the same absorption channels. Sodium, calcium and magnesium fight for the same transporter. Bisglycinate enters through a different pathway, eliminating that competition and ensuring that magnesium arrives independently of the other electrolytes present in the gel.
No adverse digestive effects. Because it is absorbed via the amino-acid pathway, bisglycinate does not exert the osmotic effect that characterizes inorganic forms. The result is magnesium that the intestine handles as easily as an amino acid — no irritation, no laxative effect, no discomfort in the middle of an effort.
Real bioavailability up to 5 times higher. Comparative studies place the absorption of magnesium bisglycinate between 80 and 90% of what is ingested, versus 15-30% for magnesium oxide, 30-40% for carbonate and 40-50% for citrate. In practical terms, 125 mg of bisglycinate delivers to the muscle an amount of magnesium functionally equivalent to 400-600 mg of carbonate — with a fraction of the digestive impact.
The difference in practice: what the athlete feels
The differences in bioavailability between forms of magnesium may sound abstract in a laboratory. In the body of an athlete during a prolonged effort, they translate into concrete and measurable consequences:
In efforts of less than 90 minutes, the form of magnesium has a limited impact. The body's initial reserves are sufficient and partial absorption of any form can be adequate.
In efforts of 2 to 4 hours, sweat losses begin to become significant. The difference between a magnesium absorbed at 40% and one absorbed at 85% starts to show up in the appearance of cramps, in the progression of muscle fatigue and in the ability to sustain intensity in the final sections.
In efforts of more than 4 hours — ultra-trails, long cycling rides, long-distance triathlons — the difference is substantial. An athlete replenishing magnesium with bisglycinate is introducing into their body, with each gel, a functionally active amount of mineral that reaches the muscle cells at the moment they need it. An athlete replenishing with carbonate or citrate is ingesting magnesium of which, at best, they will absorb half — and under digestive stress, considerably less.
Cramp prevention, reduction of neuromuscular fatigue and maintenance of efficiency in ATP synthesis are not theoretical benefits. They are real physiological advantages that accumulate kilometer by kilometer.
A technical decision that reflects a philosophy
Choosing magnesium bisglycinate for an energy gel is not a trivial decision. It is more expensive than carbonate or citrate. It requires greater knowledge of formulation to integrate it correctly with the rest of the ingredients. And it is not the kind of decision made when optimizing for cost.
It is the decision made when the formulation criterion is just one: what does the athlete's body actually need, and what is the best way to give it?
At NovaFit Energy, that question always has the same answer: the most bioavailable form, even if it is more expensive. The ingredient that works, even if it complicates the formula. Real quality, even if it reduces the margin.
Because a gel that carries magnesium in a form the body cannot absorb during effort is not delivering magnesium. It is delivering the appearance of magnesium.
And that difference, at kilometer 80 of an ultra or on the final climb of a long ride, is not a technical detail.
It is everything.
NovaFit Energy Gels — 125 mg of magnesium bisglycinate per gel. Because what matters is not what is printed on the label. It is what reaches the muscle.
