Best Magnesium Supplements for Hyrox Athletes (2025)
Cramps midway through the sled push. Restless legs the night after race day. That deep, twitchy fatigue that ibuprofen doesn't touch. If any of that sounds familiar, there's a good chance you're low on magnesium — and you're not alone.
Magnesium is arguably the most underrated recovery tool for Hyrox athletes. It costs next to nothing, it's backed by solid evidence, and most endurance athletes are deficient without knowing it. Here's what you need to know — and which products are actually worth buying in the UK.
Why magnesium matters for Hyrox recovery
Magnesium is involved in over 300 enzymatic reactions in the body, but for Hyrox athletes, four functions matter most:
Muscle relaxation
Magnesium regulates calcium flow in and out of muscle cells. Without enough, muscles stay contracted longer than they should — hello, DOMS and stiffness.
Sleep quality
It activates the parasympathetic nervous system, helping you fall asleep faster and spend more time in deep, restorative sleep — when the real recovery happens.
Cramp prevention
Low magnesium is one of the primary drivers of exercise-associated muscle cramps. Hyrox athletes lose significant amounts through sweat during those eight running segments.
Electrolyte balance
Magnesium works alongside sodium, potassium and calcium. If it’s depleted, the other electrolytes can’t do their jobs properly — leading to fatigue and poor performance.
Types of magnesium — which one do you actually need?
Not all magnesium is the same. The cheap tablets you find in supermarkets are usually magnesium oxide, which has terrible absorption (around 4%). Here are the forms that actually work:
Magnesium Glycinate
The best all-round choice for recovery and sleep. Glycinate is chelated (bonded to an amino acid), which means high bioavailability and minimal digestive upset. Take it before bed for noticeably better sleep within a week. This is the one most sports nutritionists recommend.
Magnesium Citrate
Good absorption and widely available. Slightly more likely to cause loose stools at higher doses compared to glycinate, but still a solid choice if you want a general-purpose supplement. Often found in powder form that dissolves in water.
Topical / Spray (Magnesium Chloride)
Applied directly to the skin, bypassing the gut entirely. Perfect for targeting specific areas — spray it on your quads after sled pushes or on your calves after the running segments. Some athletes find it tingles slightly on freshly-showered skin; that's normal.
Our top picks
We've tested dozens of magnesium products. These three cover every use case a Hyrox athlete needs — and they're all available on Amazon UK.
A transdermal magnesium oil spray that absorbs through the skin in minutes. Ideal for targeting specific muscle groups after a Hyrox session — spray it directly on your quads, calves or shoulders for localised relief. No digestive side effects, no waiting for absorption.
Why we rate it: Fast-acting, no stomach issues, easy to use post-race.
View on Amazon UK →Magnesium glycinate is the gold standard for sleep and recovery. Glycinate is bound to the amino acid glycine, which has its own calming properties. This makes it the best form for evening use — take it 30–60 minutes before bed and you’ll notice the difference within a week.
Why we rate it: Best bioavailability, gentle on the stomach, improves sleep quality.
View on Amazon UK →Epsom salts (magnesium sulphate) dissolved in a warm bath draw out lactic acid and deliver magnesium through the skin. A 20-minute soak after a hard training day or race is one of the simplest recovery protocols you can do. Westlab’s are pharmaceutical grade and excellent value.
Why we rate it: Cheap, relaxing, combines heat therapy with magnesium delivery.
View on Amazon UK →When and how to take magnesium around Hyrox training
Daily baseline
Take 200–400mg of magnesium glycinate every evening, 30–60 minutes before bed. Consistency matters more than timing — it takes 1–2 weeks of daily use to notice the full benefit. Don't skip days.
Post-training
Apply magnesium spray directly to the muscles you've worked hardest. After a Hyrox-style session, that typically means quads, calves, hip flexors and shoulders. Leave it on for at least 20 minutes before showering.
Race week & race day
Don't change your dose during race week — just maintain what you've been doing. After the race, an Epsom salt bath (2–3 cups in warm water, soak for 20 minutes) is one of the best things you can do in the first 12 hours. Combine it with your usual oral supplement before bed.
Frequently asked questions
Can magnesium actually prevent cramps during Hyrox?
Magnesium plays a direct role in muscle contraction and relaxation. If your levels are low — which is common in endurance athletes who sweat heavily — you’re far more likely to experience cramps during sled pushes and lunges. Supplementing consistently (not just on race day) helps maintain adequate levels and reduces cramping risk.
What is the best time to take magnesium for recovery?
For oral supplements like magnesium glycinate, take them 30–60 minutes before bed. This supports both muscle recovery and sleep quality. For topical magnesium spray, apply it immediately after training directly onto the muscles you’ve worked hardest. For Epsom salt baths, soak for 15–20 minutes within a few hours of your session.
Is it safe to take magnesium every day?
Yes. The NHS recommends up to 400mg of supplemental magnesium per day for adults. Most Hyrox athletes benefit from 200–400mg daily, taken consistently rather than sporadically. If you experience loose stools, reduce the dose slightly or switch to magnesium glycinate, which is the gentlest form on the digestive system.