What to Drink the Week Before a Marathon for Optimal Performance

December 21, 2025 •

4 min read

Approximately 75% of endurance athletes arrive at the start line already dehydrated to some degree, underscoring the importance of your pre-race fluid strategy. Understanding what to drink week before a marathon is a critical part of your taper, ensuring your body is primed for peak performance.

Quick Summary

The week before a marathon, focus on consistent fluid and electrolyte intake through water and specialized sports drinks. This strategic approach prevents dehydration and optimizes your sodium balance without overhydrating, preparing your body for the physical demands of race day.

Key Points

Start Hydrating Early: Don't wait until the day before; begin consistently hydrating seven days out to properly build your fluid levels.
Electrolytes are Crucial: Plain water is not enough. Incorporate high-sodium electrolyte drinks in the final 2-3 days to boost blood plasma volume.
Avoid Alcohol and Excessive Caffeine: Both substances can act as diuretics, promoting dehydration and interfering with muscle recovery and sleep.
Time Your Preloading: Drink your final strong electrolyte solution 90 minutes before the race, finishing it at least 45 minutes prior to allow for absorption and a final bathroom stop.
Listen to Your Body: Use urine color as a guide (pale straw is good) and drink based on thirst, avoiding forced over-hydration.
Practice Your Plan: Never try a new hydration strategy on race week. Practice your fluid and electrolyte plan during your long training runs.

Why Race Week Hydration is a Game-Changer

Many runners focus intently on their carb-loading and tapering strategies but overlook the equally vital component of hydration. The purpose of race week hydration is not to suddenly chug liters of water, which can lead to bloating and the dangerous condition of hyponatremia (low sodium levels). Instead, it's a strategic process of 'preloading' to increase your blood plasma volume and ensure you start the race fully hydrated. A properly hydrated body can more effectively regulate its temperature, deliver nutrients to muscles, and perform at its best from the starting gun to the finish line.

The Three-Stage Race Week Drinking Strategy

Your hydration plan for the final seven days before the marathon can be broken down into three key phases:

Days 7-4: Foundation Building

During this phase, your goal is to build a solid hydration base. This means focusing on consistent, moderate fluid intake throughout the day. Listen to your body and pay attention to your urine color—it should be a light, pale straw yellow.

Water: Continue to drink plenty of plain water, aiming for 2-3 liters per day, or more if the weather is warm or you are still doing light training.
Natural Electrolyte Sources: Incorporate drinks that naturally contain electrolytes to begin balancing your fluid levels. This can include coconut water or homemade electrolyte drinks with a pinch of sea salt.

Days 3-1: Strategic Electrolyte Loading

As your marathon nears, it's time to shift your focus to actively increasing your blood plasma volume. This requires boosting your sodium intake alongside your fluid consumption.

High-Sodium Electrolyte Drinks: Switch to a more concentrated electrolyte solution, ideally one formulated for preloading with a sodium concentration of around 1,500mg/liter. Drink 500ml of this solution the evening before and another 500ml about 90 minutes before the race starts.
Tart Cherry Juice: A glass or two of tart cherry juice can aid in recovery and reduce muscle soreness, making it an excellent addition to your evening routine.

Race Day Morning: Topping Off Your Tanks

Your final hydration before the race should be timed strategically to allow for absorption and a final bathroom break. Finish your preloading drink at least 45 minutes before the start.

Electrolyte Drink: Your final 500ml of high-sodium electrolyte drink is key here. It provides the final boost to your blood volume and sodium levels.
Optional Hot Drink: A small cup of coffee or herbal tea you are used to can be fine, but avoid excessive amounts of caffeine, especially if you aren't a regular coffee drinker.

Comparison of Race Week Drinks


Drink Type	Benefits	Best for...	Considerations
Water	Basic hydration, no added sugar	General daily fluid intake (7-4 days out)	Does not replace electrolytes lost during sweat; can cause hyponatremia if overconsumed.
High-Sodium Electrolyte Drink	Increases blood plasma volume, balances sodium levels	Final 2-3 days before race	Must be formulated correctly to avoid gastric distress.
Standard Sports Drink (e.g., Gatorade)	Replaces carbs and electrolytes	During the race, not ideal for preloading	Lower sodium levels are not sufficient for effective preloading.
Coconut Water	Natural source of potassium and electrolytes	General hydration throughout the week	Often lower in sodium than specialized drinks; good for flavor variation.
Tart Cherry Juice	Anti-inflammatory properties, aids recovery	Evening drinks, especially the night before	Don't try for the first time during race week.
Herbal Tea	Can be soothing and contribute to fluid intake	A calming evening drink; avoid caffeinated versions	Ensure it's decaffeinated to promote good sleep.

What to Avoid the Week Before Your Marathon

Just as important as what you should drink is what you should avoid. Certain fluids can undermine your careful hydration and carbohydrate-loading efforts.

Alcohol: This is a diuretic, meaning it promotes dehydration and hinders muscle recovery. Avoid it entirely in the final week.
Excessive Caffeine: While a small morning coffee is fine for regular drinkers, overdoing it or starting a new routine can lead to dehydration and jitters.
Highly Acidic or Sugary Juices: These can cause stomach upset and are not ideal for topping off glycogen stores. Stick to simpler sources of carbohydrates.
New Products: Never introduce a new drink, supplement, or food during race week. Stick to what you've practiced during your long training runs.

Conclusion

Your hydration strategy in the week leading up to a marathon is as crucial as your long training runs. By focusing on consistent water intake, incorporating strategic high-sodium electrolyte drinks in the final days, and avoiding dehydrating agents like alcohol, you can optimize your blood plasma volume and sodium levels. This meticulous approach ensures you arrive at the start line perfectly prepared, not just rested and carb-loaded, but also optimally hydrated for the monumental effort ahead. Remember, listening to your body and practicing your plan during training is the ultimate recipe for success on race day.

Frequently Asked Questions

Aim for consistent, moderate intake of plain water, typically 2-3 liters per day. Pay attention to your urine color, which should be a pale yellow, and drink more if you're training or in warm weather.

Start increasing your electrolyte intake, particularly sodium, during the final 2-3 days before your race. Use a high-sodium solution during this period to boost blood plasma volume.

While standard sports drinks are useful during the race for carb replenishment, a specific, high-sodium electrolyte drink is more effective for 'preloading' in the 2-3 days leading up to the race.

It is best to avoid alcohol entirely during race week. It is a diuretic that can cause dehydration, impair recovery, and disrupt sleep, all of which are detrimental to race performance.

Hyponatremia is a dangerously low blood sodium level. You can avoid it by not over-drinking plain water and by consistently taking in electrolytes, especially sodium, in the days before the marathon.

If you are a regular coffee drinker, your usual morning cup is likely fine. However, avoid excessive amounts and never introduce caffeine into your routine for the first time during race week, as it can be a diuretic.

For optimal hydration and a final bathroom break, aim to finish your last 500ml of fluid at least 45 minutes before the starting gun.