A gentle pace, for eight hours, in the sun.
Hiking never feels like a workout — which is exactly why people under-prepare for it. It's hours of steady effort under direct sun, often with a pack and sometimes at altitude, and the fluid and sodium losses stack all day. By the descent they show up as the headache, the heavy legs, the cramp on the last mile. Here's how to carry the right sodium and drink to thirst.
Get your trail number →A long day fails in both directions.
A salty sweater on a hot, exposed climb loses a lot of sodium over a day — far more than the water in the reservoir replaces. That's the classic hiking headache and the cramp on the way down.
Why you cramp →On a slow all-day hike, dutifully sipping plain water for eight hours can dilute your blood sodium toward hyponatremia — the more dangerous failure, and one hikers do reach.
Can you drink too much? →The same "just drink water" advice pushes the salty sweater toward the first and the careful sipper toward the second. Sweat sodium varies about tenfold between hikers, so the honest input is your own — not a rule of thumb printed on a bottle.
Pack it right for the day.
Start hydrated, and carry sodium — not just water. A day of losses is easier to keep up with than to claw back once you're deep in a headache miles from the car.
Weigh a training hike once to learn your real hourly loss under a pack and sun. How to do it → Then the calculator sizes your sodium for the hours you'll be out.
Drink to thirst, take the shade, watch the descent. Heat, altitude and a long day compound; if a headache turns severe or comes with confusion, that's a medical concern, not a hydration tweak.
Keep reading
Your sweat rate
Weigh a hike under your pack — the sun and the steady pace hide how much you lose.
Too much water
Why an all-day sipper can dilute their blood sodium, and how to avoid it.
Marathon hydration
The same two-sided problem, at pace instead of on the trail.