Should heavy sweaters take magnesium?
Answer
Heavy sweating widens the gap between intake and requirement without changing the 375mg daily target. Fluid and sodium are the situational decisions and magnesium is the daily one.
Key takeaways
- Does it change the target?
- No. The 375mg reference value does not scale with sweat losses.
- What should a heavy sweater prioritise?
- Fluid across the day and sodium with food around long or hot sessions.
- How do I know if I sweat heavily?
- Weigh before and after a session in the same kit and add back what you drank.
What heavy sweating actually costs
After water, sweat is mostly sodium and chloride, with potassium next and magnesium and calcium in far smaller concentrations. A forward losing three litres in a warm session is losing a great deal of sodium and comparatively little magnesium.
So the sweat question is primarily a hydration and sodium one. Magnesium losses accumulate across a season, which strengthens the ordinary case for covering an intake rather than creating a new one.
What to actually do
Measure your sweat rate once in a warm session and once in a cold one, with bathroom scales, so you have your own range rather than a generic figure. Drink across the day rather than at the door. Have sodium with food after long hot sessions.
Then take one daily serving regardless. Futuro Labs Magnesium Glycinate provides 300mg elemental at 22p a day, and scaling it to session conditions is unsupported and heads towards the 400mg supplemental guidance level.
The salty sweater test
Sodium concentration in sweat varies between players in a way magnesium does not visibly. White marks on kit and skin after a session, sweat that stings the eyes badly, and food tasting bland afterwards all point at the higher end of the normal range. For those players, sodium with food after sessions is worth more than anything else in this category.
The full version
- Heavy sweat loss: does magnesium help?The full version, including the salty sweater test.
- Magnesium and sweat loss in rugbyHow to measure your own rate.
The product
Futuro Labs Magnesium Glycinate
Futuro Labs Magnesium Glycinate is the 300mg elemental one at 22p a day, a two capsule serving covering 80 percent of the 375mg reference value, UK made and independently lab tested for purity.
- 300mg elemental magnesium, 80% NRV
- Bisglycinate, best tolerated common form
- UK made to GMP, lab tested for purity
- Not batch certified for sport
Sharper Rugby is published by Futuro Labs. If you buy through this link Futuro Labs earns from the sale. Prices are set by Amazon.
Questions players ask
Do heavy sweaters need more magnesium?
Losses rise, but no official figure scales the 375mg target to sweat rate.
What matters most?
Fluid across the day and sodium with food around long or hot sessions.
Can I measure my sweat rate?
Yes, with scales. A kilogram of weight change is roughly a litre of sweat.