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Scenario answer

Fueling a cool marathon as a heavy, salty sweater

Cool weather does not switch off a high sweat rate. If your kit is white with salt after a long run, sodium still belongs in the plan.

Carb target for this profile
70 g/hr
To hit ~70 g/hr carbs: about 2.3 C30 Fuel Drink Mix per hour (69 g/hr). Heavy/salty sweat: add an electrolyte drink at ~400–1000 mg/L sodium, for example Hydration Drink Tabs. Sodium's job is to keep you drinking (about 59% more fluid, Cosgrove 2013). It has no effect on cramping.

The three-product answer

Electrolyte pairing for this profile: GU Energy Hydration Drink Tabs or Nuun Sport Tablets. Sodium's job is keeping you drinking, not preventing cramp.

Why

A salty sweater loses more sodium per litre than average, and on a cool day the reminder to drink is weaker, so intake drifts low. The carb target stays in the normal 60–75 g/hr band; the sodium question is the one to get right.

What matters: sodium in what you drink, at a concentration that keeps you drinking, or a salt capsule with water at fixed intervals if your fuel is low-sodium gels. Sodium does not prevent cramp — that claim does not survive the studies — but it keeps fluid intake up.

The trap is over-drinking plain water on a cool day because you feel fine. Drink to thirst, fuel to schedule.

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