Hydration test
Sweat Rate
Calculation Guide
Turn hydration from a guess into a number by measuring what the athlete actually loses during a normal practice.
Normal practiceHot weatherRetest in new conditionsCoach-run test
2
Weigh-ins
1
Session
Every sip
Bottle log
Hourly target
Outcome
How the sweat-rate test works
Weigh in dry. Log every bottle. Weigh out fast. Save the hourly number with the weather.
When to retest
- Hotter weather Run the test again when heat or humidity climbs enough that the old number no longer fits.
- Longer or harder session Use a session that actually matches the training or race demand you care about.
- Travel, altitude, or bigger workload changes Dry air and changed conditions can move the number enough that the old test no longer fits.
Test checklist
Before
dry weigh-in and session length recorded
During
every bottle, cup, and refill logged
After
same-scale weigh-out immediately
Result
write down the hourly number with the weather
What not to assume
Do not call one sloppy test a hydration plan.Do not assume one cool-weather number covers every hot meet.Do not forget that heavy sweaters may need sodium planning too.
Write the hourly number down with the weather notes so the athlete can actually use it later.