Horse Performance and Magnesium

Performance horses, especially race horses, polo horses and cross country endurance racers, can push until nothing is left in the tank – and then they will give more. Apart from the actual performance, transport to and from the event and inclement weather can also cause stress, leading to magnesium deficiency. How can magnesium supplementation help your horse cope and recover better?

Performance Stress Increases Magnesium Deficiency

The more stress, the more magnesium is lost from cells. To add to the risk of magnesium deficiency, soils can become magnesium-depleted, which means grasses can have high sugar in relation to magnesium.  Sugars require a lot of magnesium to be metabolised. When magnesium is low and sugar is high, it can lead to the development of diabetes over time as the body has to convert the unused sugars to stored adipose fat.

Other adverse side effects include acidosis due to acidic byproducts from sugar metabolism. This leads to low oxygen status and therefore low energy and fatigue. As magnesium drops lower, the risk of inflammatory states increases. The more inflammation the more likelihood of calcium deposits in soft tissue and joints where there has been repetitive stress injury and inflammation. You can pretty well track magnesium status lower and lower by the escalation of these kinds of symptoms.

What other symptoms might you notice if your horse was low in magnesium?

They may get easily spooked at the slightest trigger or get involuntary muscle spasms. They may get cantankerous and grumpy, unwilling to cooperate, and not responsive to rehearsed commands. That’s the last thing you need in a performance horse! 

In fact, cortisol and adrenaline release is increased as a direct response to low magnesium itself. [1] It’s almost as though the system goes on auto-pilot, continuing to release stress hormones long after the need for ‘fight or flight’ has passed. Magnesium replenishment however, helps to dampen excessive stress hormones and move horses back to parasympathetic mode (grazing mode) so that they can calm down, relax and recover stronger.  If they are constantly in ‘flight-or-flight’ sympathetic mode, the system does not have enough opportunity to recover. This can affect heart rhythm and the efficiency of the whole cardiovascular system. A horse can even have a heart attack if cell magnesium levels drop too low. This has happened in the case of very over-worked and over-stressed horses without enough magnesium available to recover. Note the importance of magnesium to the heart muscle, which has to work 24/7. There are more magnesium receptors in the heart muscle than the other muscles in the rest of the body. We need to pay a lot of attention to (and care for) this muscle in performance horses!

Magnesium for Electrolyte Balance

Magnesium nutrition is safe and effective. This vital macro mineral, used by the body constantly, is needed in great amounts. Magnesium is the ‘Master Mineral Electrolyte’ that controls how calcium is used in the body. Studies have shown that it is magnesium that is usually depleted before the other electrolytes become depleted and out of kilter. It is also an essential co-factor with potassium and sodium, as well as many other nutrients. Magnesium is essential for enzyme activity, which means thousands of cellular processes are dependent on the availability of magnesium. This is because mitochondria need enough magnesium to make Adenosine Triphosphate (ATP) – our little electrical energy batteries. Plugging into magnesium is like plugging into a power source.

Optimal magnesium does not push stress hormones or blood pressure down too low (as a drug would), but instead promotes balance. The body uses magnesium to self-regulate. This is very important because when we need to push, calcium shots are available to stimulate the muscle quickly, but enough magnesium is also available for the calcium to retreat in the recovery phase. This avoids involuntary twitches and muscle spasms, and makes the horse more controllable and responsive.

During rest phases promoted by plentiful magnesium, cells also have a chance to cleanse and detox, repair and renew, and therefore to recover better and stronger. This means that over time, as daily magnesium supplementation restores cellular magnesium reserves, the horse will improve in energetic performance, in muscle flexibility and recovery, as well as in temperament, focus and obeying of commands.

See ‘Feeding Method’ for how to supplement food grade magnesium chloride flakes in daily feeds.

See TRIAL – Transdermal Application of Magnesium For Horses (for treatment of muscle spasms or tightness)

By Sandy Sanderson © (

1. Fawcett, W.J., E.J. Haxby, and D.A. Male, Magnesium: physiology and pharmacology. BJA: British Journal of Anaesthesia, 1999. 83(2): p. 302-320.

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