The complete report, exactly as it’s delivered.
Read it top to bottom: the headline sodium loss first, then the electrolyte panel and the workout it was measured during, then the race-day plan you can dial to your own event. The last three sections show the working — the patch correction, the sweat-rate arithmetic, and what the target means in bottles and packs.
You're a heavy sodium sweater — targeted electrolyte replacement is especially important for you, particularly in the heat.
| HOUR | FLUID ESTIMATE | SODIUM ESTIMATE |
|---|---|---|
| Hour 1 | 650ml | 950mg |
| Hour 2 | 700ml | 1,050mg |
| Hour 3 | 800ml | 1,200mg |
| Hour 4 | 850ml | 1,300mg |
Your hour-by-hour sodium target for the race you picked — race length sets the hours, while intensity and heat set how high each bar climbs.
A patch worn on the forearm reads saltier than the body as a whole. Reporting the raw number would overstate the losses, so it’s converted with a published regression — and both the input and the conversion are shown here rather than asserted.
Baker LB, Barnes KA, Anderson ML, Passe DH, Stofan JR. Normative data for regional sweat sodium concentration and whole-body sweating rate in athletes. J Sports Sci. 2016;34(4):358–368.
The regression is strong across a group (R² ≈ 0.70) but individual prediction error is wide — roughly ±12–14 mmol/L at the 95% limits of agreement. The whole-body value is a well-grounded estimate, not an exact figure, and we’d rather you knew that.
No model and no wearable estimate — a scale. Body mass before and after, plus whatever was drunk in between. Concentration alone says nothing about volume, and it’s volume that turns a salty result into a large hourly loss.
No brands, on purpose — we don’t sell a mix and we’re not paid to point you at one. Each row is a FORMAT and the sodium density it assumes, so you can check your own label against it and scale from there.
| Format | To hit the target | Sodium | Fluid |
|---|---|---|---|
Standard bottled sports drink ~110 mg sodium per 16 oz bottle | 10 bottles/hr not realistic | 1,100 mg | 5,000 mL |
Energy chews ~90 mg sodium per pack | 12 packs/hr not realistic | 1,080 mg | — |
Salt / electrolyte capsules ~200 mg sodium per capsule | 6 capsules/hr | 1,200 mg | — |
Standard electrolyte drink mix ~300 mg sodium per scoop, mixed into ~500 mL | 3.5 scoops/hr | 1,050 mg | 1,750 mL |
Endurance-formula tablet ~500 mg sodium per tablet, dissolved in ~750 mL | 2 tablets/hr | 1,000 mg | 1,500 mL |
High-sodium drink mix ~1,000 mg sodium per stick, mixed into ~500 mL | 1 stick/hr | 1,000 mg | 500 mL |
The rows marked not realistic are the useful ones. At this loss rate a standard sports drink would mean drinking well past what anyone can absorb — which is how an athlete doing everything “right” still ends up badly short on sodium.
This exact report, with your numbers in it.
The figures above belong to one athlete, and sodium losses vary roughly tenfold between people — which is the whole reason to measure rather than guess. Wear a patch during a workout you had already planned, weigh in before and after, and mail it back in the prepaid envelope.