By Monica N. for Stacked Fitness Hydration
SEPTEMBER 6, 2026 • 8 MIN READ
Key Takeaways
- The American College of Sports Medicine recommends starting exercise already hydrated, drinking roughly 5 to 7 milliliters of fluid per kilogram of body weight about four hours before training.
- Sweat rates vary widely between individuals, with case-series data on endurance athletes showing a range from under half a liter to more than two liters of fluid lost per hour.
- Even mild dehydration, as little as one to two percent of body mass lost through sweat, has been shown to impair mood and sustained attention.
- Creatine draws extra water into muscle cells and raises baseline fluid needs, which is why Stacked Fitness Hydration's TONE pairs 5g of creatine with 980mg of electrolytes in a single daily stick.
Get your hydration timing right, and you can blunt fatigue and protect your focus. That matters more than the number on your water bottle.
Most people treat hydration like a daily step count. Hit a total number, and you assume you are covered.
Exercise physiology does not work that way. When you drink changes how your body uses the fluid, not just how much you drink.
Why Hydration Timing Beats a Daily Water Total
A single ounce total for the day tells you almost nothing about a workout that starts in twenty minutes.
The American College of Sports Medicine's position stand on exercise and fluid replacement makes this point directly. Athletes should start exercise already hydrated, not catching up mid-session. That shift, treating hydration as a schedule instead of a scoreboard, is the whole idea behind hydration timing.
The cost of poor timing shows up fast. Even mild dehydration in the range of one to two percent of body mass has been linked to worse mood and weaker attention. That happens before thirst even kicks in.
Once you think in windows instead of totals, three checkpoints matter most. Before you train, during the session, and in the hours right after.
Before You Train: The Pre-Hydration Window
Showing up dehydrated puts you behind before the first rep.
Sports dietitians generally suggest drinking about 5 to 7 milliliters of fluid per kilogram of body weight roughly four hours before exercise. Add a smaller top-up closer to start time if your urine still looks dark. For a 70 kilogram adult, that four-hour window works out to roughly 12 to 16 ounces, not a gallon in one sitting.
Spacing the intake matters as much as the amount. Sip steadily over the four hours instead of drinking it all at once. That gives your kidneys time to use the fluid instead of flushing most of it out as urine.
This window is also the easiest place to build a habit around a hydration supplement. A morning electrolyte stick with your first glass of water does more for your afternoon workout than an extra bottle of plain water five minutes before you train.
Morning hydration deserves its own mention too. You lose fluid overnight just through breathing and normal skin evaporation. Treat your first glass of the day as part of this pre-hydration window, not a separate habit.
During Exercise: Matching Intake to What You Are Actually Losing
Sweat loss during a single hour of training varies enormously from person to person.
A case-series study of endurance-trained athletes recorded sweat rates ranging from under half a liter per hour to more than two liters per hour. That was among people doing similar workouts side by side. Body size, heat, humidity, and effort all play a role, which is why a flat "drink eight ounces every twenty minutes" rule fails so many people.
Sweat is not just water either. Normative data on sweat sodium losses across sports shows sodium concentration in sweat also varies widely between individuals. That is part of why plain water alone can leave you feeling worse during a long or hot session, not better. Replacing electrolytes alongside fluid keeps the water in your cells and bloodstream, where it is actually needed, instead of passing straight through.
If you train for more than 60 to 90 minutes, or sweat heavily in the first thirty, that is your cue. Add electrolytes to your water instead of relying on water alone.
After Exercise: Closing the Rehydration Gap
What you drink in the hours after training sets up your next session.
Sweat losses include both water and sodium. Replacing only the water can leave you under-recovered, even after you feel like you have had enough to drink. A common post-exercise target is roughly 1.25 to 1.5 liters of fluid for every kilogram of body weight lost. Include some sodium so your body actually retains it instead of losing it again through extra urination.
Weighing yourself before and after a hard workout gives you a real number to work from instead of a guess. A pound lost during training is roughly 16 ounces of fluid to replace on top of your normal intake for the day.
This step gets skipped more than any other in a hydration timing plan. People rehydrate until thirst goes away, then stop. Thirst fades well before the fluid and sodium deficit is actually closed, so replacing the number you weighed, not just the feeling of being satisfied, is what closes the gap.
How Electrolytes and Creatine Fit Into Your Hydration Timing
Creatine and hydration are not two separate habits. They are one system, and getting the timing right on one affects the other.
Creatine works partly by pulling extra water into your muscle cells. That is good for strength and recovery, but it also raises your baseline fluid needs slightly once you start supplementing. Electrolytes, sodium in particular, help move that water where it needs to go instead of sitting unused. We covered the research behind this in our piece on why electrolytes help your body absorb more creatine.
This is exactly the gap a combined hydration supplement is built to close. Instead of timing a plain creatine dose, a separate electrolyte packet, and your water intake as three different decisions, one stick handles all three. That is the idea behind Stacked's TONE: a creatine and electrolyte hydration mix, not either ingredient on its own.
Building a Hydration Timing Routine You Will Actually Keep
None of this works if it stays in a research summary. The goal is a routine simple enough for a busy Tuesday, not just a perfect Saturday long run.
- Drink 12 to 16 ounces of fluid, ideally with electrolytes, in the four hours before a workout, sipped steadily rather than chugged
- During sessions longer than 60 minutes, add electrolytes to your water instead of relying on plain water alone
- Weigh yourself before and after your hardest sessions, then replace roughly 1.25 to 1.5 liters per kilogram lost
- Pair your creatine dose with your hydration routine, since creatine slightly raises your baseline fluid needs
None of this requires special equipment or a coach with a clipboard. A kitchen scale for the occasional weigh-in, a water bottle you actually refill, and one electrolyte source you keep stocked cover most of what the research points to.
Put together, that is the full loop this article walked through. Hydrate ahead of training. Match your intake to what you are actually losing during it. Close the gap afterward with fluid and sodium. Let electrolytes and creatine work together instead of against each other. None of the individual pieces are complicated. The timing is simply what most people skip.
For more on this, see how much water active adults really need.
Further reading
- American College of Sports Medicine, Position Stand: Exercise and Fluid Replacement
- Mild dehydration impairs cognitive performance and mood of men, British Journal of Nutrition
- A Case-Series Observation of Sweat Rate Variability in Endurance-Trained Athletes, PMC
- Normative data for sweating rate and sweat sodium loss in athletes, Journal of Sports Sciences
