Race-Day Electrolyte Timing: How to Build the System

Race-day hydration is not about hitting one universal sodium number.

Sweat rate, sweat sodium concentration, temperature, race duration, pace, body size, acclimation, and fluid intake can all change what an athlete needs. The objective is to start hydrated, replace fluid and electrolytes at a rate you have already tested, and avoid both significant dehydration and unnecessary overdrinking.

For IV-X, the system is simple:

ENERGY.150 before output.
ENDURE.730 as duration, heat, and sweat load increase.

The exact timing should be developed in training.

T–90 TO T–30: START HYDRATED

Race morning is not the time to aggressively load water or sodium.

Begin with your normal breakfast and normal fluid intake. The goal is to arrive at the start hydrated—not carrying excess fluid.

If conditions are hot, you are a heavy sweater, or your normal pre-race routine includes electrolytes, ENDURE.730 can be worked into this window.

ENDURE.730

500mg sodium · 200mg potassium · 30mg magnesium

One 16 oz can provides 730mg total electrolytes, including 500mg sodium.

Sodium is the primary electrolyte lost in sweat, but individual losses vary substantially. That is why ENDURE.730 should be treated as a measurable part of your overall hydration strategy—not an automatic prescription to consume one can at a fixed interval.

ACSM recommends individualized fluid-replacement strategies because sweat rates and electrolyte losses differ significantly between athletes.

T–60 TO START: DEPLOY ENERGY.150

For athletes who already use caffeine before competition, this is where ENERGY.150 fits.

ENERGY.150

150mg green-tea caffeine · 215mg electrolytes

ENERGY.150 provides a controlled caffeine dose alongside sodium, potassium, and magnesium in a non-carbonated formula.

Caffeine has extensive evidence supporting endurance performance, although response varies between athletes. Research most consistently supports caffeine doses around 3–6mg/kg body weight, with lower doses potentially providing benefit for some athletes as well.

That does not mean every runner needs to target 3–6mg/kg.

ENERGY.150 contains 150mg caffeine per can, allowing caffeine to be incorporated as a defined input instead of continually stacking coffee, gels, chews, and other caffeinated products without tracking the total.

Race-day rule: know how much caffeine is coming from every source.

If you have never raced with caffeine, race morning is not the time to introduce it.

START → EARLY RACE: DO NOT CHASE THE PLAN

Once the race begins, hydration should respond to the work being performed.

For shorter races or cool conditions, electrolyte requirements may be relatively modest. Longer duration, higher temperatures, humidity, and higher sweat rates generally increase fluid and sodium losses.

But more is not automatically better.

Do not force fluid simply because a schedule says it is time to drink. Excessive fluid consumption is the primary driver of exercise-associated hyponatremia during endurance events, and sodium supplementation does not make overdrinking safe.

Use aid stations and natural drinking opportunities rather than attempting to “catch up” with large fluid volumes later.

DURING LONG OR HOT EFFORTS: MOVE TO ENDURE.730

As duration and sweat loss accumulate, ENDURE.730 becomes the primary IV-X race-day formula.

Each can provides:

500mg sodium
200mg potassium
30mg magnesium
730mg total electrolytes
0mg caffeine

This makes the formula useful when electrolyte replacement is needed without continuously increasing caffeine intake.

Rather than thinking:

“One ENDURE every hour.”

Think:

“How does this serving fit into my total fluid and sodium intake?”

Your total should account for:

• ENDURE.730

• aid-station sports drinks

• gels or chews containing sodium

• salt capsules

• food

• plain water

One athlete may lose substantially more sodium in sweat than another. Environmental conditions can also change those losses from one race to the next.

That is why a practiced plan is more useful than copying another athlete’s hourly intake.

WHAT ABOUT CARBOHYDRATES?

Electrolytes are only one component of race fueling.

ENERGY.150 and ENDURE.730 are zero-sugar formulas. They are not intended to replace race-day carbohydrate intake.

For prolonged endurance exercise, carbohydrates should come from a separate fueling source such as gels, drink mix, chews, or food according to the athlete’s practiced nutrition strategy.

Hydration, electrolytes, carbohydrates, and caffeine solve different problems.

The system should account for all four.

LATE RACE: CONTROL THE VARIABLES

As fatigue increases, athletes often begin reacting instead of executing.

They drink more because they feel bad.
They add salt because they are cramping.
They take additional caffeine because pace is falling.

That can create more problems than it solves.

Late in a race, continue using the same framework you practiced:

Fluids according to thirst and expected losses.
Electrolytes according to the overall plan.
Carbohydrates according to your fueling strategy.
Caffeine with awareness of your cumulative dose.

Electrolytes should not be treated as a guaranteed solution for cramps, fatigue, heat illness, or declining performance.

THE IV-X RACE-DAY SEQUENCE

01 — PREPARE

T–90 to T–30

Normal breakfast. Normal fluid intake.

Use ENDURE.730 if electrolyte intake is already part of your practiced pre-race routine.

02 — DEPLOY

T–60 to Start

Use ENERGY.150 if caffeine is part of your established race strategy.

150mg caffeine + 215mg electrolytes.

Account for caffeine coming from every other source.

03 — SUSTAIN

During prolonged output

Transition toward ENDURE.730 when heat, duration, and sweat loss make additional electrolyte intake appropriate.

500mg sodium + 230mg potassium/magnesium.

Build it into your total intake rather than treating it as an isolated hourly requirement.

04 — ADAPT

Conditions change.

Your race-day plan should be able to change with them.

Higher heat, higher sweat rate, longer duration, slower-than-expected finishing time, stomach tolerance, and aid-station availability can all alter what works.

Race day is execution. Training is where the system gets built.

BUILD IT BEFORE YOU RACE IT

The best electrolyte strategy is the one you have already tested.

Use long runs and race-specific sessions to determine:

• how much fluid you naturally tolerate

• how quickly you sweat in different conditions

• whether you are a relatively salty sweater

• how ENDURE.730 fits with your other sodium sources

• how ENERGY.150 fits with your total caffeine intake

• how your carbohydrate plan works alongside both formulas

Do not introduce a completely new hydration or caffeine protocol on race morning.

RESEARCH

American College of Sports Medicine — Exercise and Fluid Replacement
ACSM recommends individualized hydration strategies because sweat rate and sweat electrolyte concentrations vary considerably between athletes. The goal is to begin exercise hydrated while limiting excessive dehydration and major electrolyte disturbances during exercise.

Guest NS et al. — International Society of Sports Nutrition Position Stand: Caffeine and Exercise Performance (2021)
Caffeine can improve endurance performance, with evidence most consistently supporting approximately 3–6mg/kg, while individual response and tolerance vary.

Hoffman MD et al. — Sodium Supplementation and Exercise-Associated Hyponatremia During Prolonged Exercise
Research in ultramarathon runners found that overhydration, rather than inadequate sodium supplementation, was the primary characteristic associated with exercise-associated hyponatremia.

Exercise-Associated Hyponatremia Review
Prevention centers on avoiding excessive fluid consumption, with thirst-guided drinking providing an individualized strategy for many endurance athletes.

This article is educational and is not an individualized hydration, nutrition, or medical prescription. Athletes with medical conditions, kidney or cardiovascular disease, or medications affecting fluid or electrolyte balance should discuss race-day hydration with a qualified healthcare professional. Stop racing and seek medical support if significant confusion, altered mental status, repeated vomiting, severe weakness, or other concerning symptoms occur.