Cardio

Sweat-Rate + Electrolyte Marathon Plan

Compute marathon sweat rate and a personalized fluid + sodium intake plan from a single training session.

Result

Fluid intake / hour

460 mL/h

Sodium per hour

529 mg

Sweat rate

570 mL/h

Body mass lost

2.1%

Per hour of racing.

Sweat rate

570 mL/h

Drink

460 mL/h

Education, not medical advice. The result comes only from the published formula and your inputs. How we check our formulas.

Formula Marathon Sweat Rate + Electrolyte Formula
Marathon hydration: sweat rate 0.5-2.5 L/h, sodium concentration 460-1840 mg/L. Casa 2007 + ACSM 2007 standards. Replace 70-90% of losses; avoid hyponatremia.

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10 min read Heat Acclimatization: Sodium and Plasma Volume
Heat acclimatization shifts plasma volume up 10-12% in 10-14 days. The sodium math that supports the adaptation and the workouts that drive it.
7 min read Marathon Sweat Rate: 70kg Runner, 2% Body Mass Loss in Warm Conditions
Marathon sweat rate 0.57 L/h, total loss 2.3 L over a 4-hour temperate race. Body mass loss 2.1%, 460 ml/h fluid plan, 529 mg/h sodium target.
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Heart-rate zone methods compared: Karvonen, %HRmax, %HRR, lactate threshold — accuracy by training age, error bands, and which one for which goal.

The same calculation as a JavaScript module you can import. It runs where you import it, with no request, key or rate limit.

import { compute } from "https://aifithub.io/engines/sweat-rate-electrolyte-marathon.js";