11/06/2026
Most cyclists take magnesium for cramps. The science says it probably won't help.
That's not an opinion. When researchers pulled together the best controlled trials - the gold-standard Cochrane review - magnesium supplements did not meaningfully reduce how often people cramped, or how badly.
Yet "take magnesium for your cramps" is the most repeated piece of advice in cycling.
So if magnesium isn't your cramp cure, what is it actually good for? Quite a lot, as it turns out - and the type you buy matters more than most riders realize.
Magnesium is a workhorse mineral. Your body needs it for the very thing that powers every pedal stroke: ATP, the fuel your muscles burn, only works when it's bound to magnesium. No magnesium, no usable energy.
Where it genuinely earns its place for cyclists over 40:
• Sleep quality - higher magnesium intake is linked to better, longer sleep in large studies, and sleep is where your training actually sticks
• Muscle recovery - supplementing around the daily requirement has been shown to lower muscle-damage markers and soreness after hard efforts
• Energy metabolism - it's central to how you turn food into watts
• Nervous system and stress - it helps calm an over-revved system after a big day
Now the part the supplement aisle won't tell you - the forms are not interchangeable:
The well-absorbed, rider-friendly ones:
• Glycinate - gentle on the gut, the go-to for sleep and recovery
• Citrate - well absorbed, but can loosen your stools (not what you want mid-ride)
• Malate - a reasonable daytime option often tied to energy
The ones to think twice about:
• Oxide - cheap, but poorly absorbed; it's really a constipation remedy
• Sulfate (Epsom salts) - a laxative or a hospital IV drug, not a daily supplement
• L-threonate - interesting for brain/cognition, but expensive and overkill for most
And here's the honest truth: more is not better. Too much - or the wrong form - mostly buys you a dash to the toilet. Real deficiency is uncommon in cyclists who eat well, because nuts, seeds, beans, whole grains and leafy greens are loaded with it. You lose surprisingly little through sweat - a long ride sheds about what's in a slice of bread.
Magnesium is worth getting right. Just get it right for the reasons that hold up - sleep, recovery, energy - not the one that doesn't.
And if you've got kidney issues or take regular medication, have a quick word with your doctor before adding any supplement.
What do you actually take magnesium for? 👇
