Magnesium, Exercise and Sudden Cardiac Arrest

Fear mongering is never cool. We are not about to suggest that you fear exercise, or treat your heart like a delicate flower on the treadmill. No. Sudden Cardiac Arrest while exercising is rare.

Here’s how rare: In a study published in the medical journal Circulation, investigators studied over 1,000 people aged 35-65 who had experienced a sudden cardiac arrest. Just 5 percent had a sudden cardiac arrest during sports activities. (Cedars-Sinai)

Why Sudden Cardiac Arrest Occurs

In many cases, Sudden Cardiac Death (SDC) during exercise happens because of an existing heart condition – known, or unknown. In other cases, SCD may be caused by a sudden interruption in the heart’s rhythm.

The body is electric”, as Dr. Carolyn Dean reminds us in The Magnesium MiracleMagnesium transmits electrical impulses within the heart’s cells and influences the rhythm of contraction and relaxation in the heart.

In Sudden Cardiac Arrest, “the electrical system to the heart malfunctions and suddenly becomes very irregular. The heart beats dangerously fast. The ventricles may flutter or quiver (ventricular fibrillation), and blood is not delivered to the body.”(WebMD)

Dr. Dean cites a study of young, healthy, well-conditioned men, noting that “strenuous effort was reported to give rise to persistent magnesium deficiency and a related long-term increase in cholesterol, triglycerides, and blood sugar.” The study results suggest “the sudden death of athletes and other intensely training individuals during extreme exertion is triggered by the detrimental effects of persistent magnesium deficiency on the cardiovascular system.” (The Magnesium Miracle, Kindle page 2133)

Another study found that higher plasma and dietary magnesium levels were associated with lower rates of SCD. Potassium, too, has a protective effect against SCD, according to a 2010 review (Today’s Dietician).

Interestingly, “it’s impossible to overcome potassium deficiency without replacing magnesium” – the two are intimately related (The Magnesium Miracle, Kindle page 157). Potassium levels are often cited in discussions of arrhythmia, cardiovascular mortality and heart failure, but without enough magnesium, “the body is unable to deliver potassium to the cells” (The Magnesium Miracle, Kindle page 2463).

What Does This Mean For You?

There are many, many reasons to get enough magnesium. You need it for sleep, energy, stress management, mood regulation, brain health, strong bones, healthy blood sugar, inflammation and more.

The fact that magnesium may prevent SCD during exercise is also amazing.

Taking Natural Calm won’t offset a poor diet, smoking, drinking too much alcohol or pushing your limits with an existing heart condition. It will equip your heart with what it needs to maintain a healthy rhythm.

The importance of magnesium for the heart doesn’t stop here, though. This hard-working mineral also plays a fascinating role in managing cholesterol, arterial plaque and blood pressure – topics for another blog post.

In the meantime, spread the word. Heart attacks and stroke are top killers in Canada. Everyone should be aware that magnesium can help.

This wraps up our series on magnesium as ‘the fitness’ mineral. If you work out – or want to – be sure to check out our post on energy, lactic acid, and the magnesium needs of those who exercise.


Carolyn Dean, MD, ND. The Magnesium Miracle (Revised and Updated). Kindle Edition.

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