Are You Supposed to Drink Water During Cardio?

January 9, 2026 •

4 min read

Research has shown that a fluid loss of just 2% of your body mass can significantly hinder exercise performance, which directly answers the question: are you supposed to drink water during cardio?. Proper hydration is not just about quenching thirst; it is a critical component of maintaining stamina, body temperature, and overall safety during any cardiovascular workout.

Quick Summary

This article explores the critical role of hydration during cardiovascular exercise, outlining how fluid intake impacts performance, safety, and recovery. It provides guidelines on when and how much water to consume, details the risks of dehydration, and compares hydration options beyond plain water.

Key Points

Start Hydrated: Begin your workout already well-hydrated by drinking water in the hours leading up to your cardio session.
Sip, Don't Gulp: Drink small, frequent sips of water every 10-20 minutes during cardio to avoid stomach discomfort and maintain consistent hydration.
Performance is Affected: A fluid loss of just 2% of body weight can decrease athletic performance, highlighting water's importance during exercise.
Recognize Dehydration Signs: Don't rely solely on thirst. Watch for signs like fatigue, headaches, darker urine, or an increased heart rate, which signal dehydration.
Consider Electrolytes: For intense or long-duration cardio, a sports drink containing electrolytes can help replenish lost salts and energy, though water is sufficient for shorter sessions.
Replenish Post-Workout: Rehydrate after your workout to replace lost fluids and aid recovery. Weighing yourself can help you accurately gauge how much to drink.

Why Hydration During Cardio is Non-Negotiable

Drinking water during cardio is not optional; it's a physiological necessity. When you engage in cardiovascular exercise, your body's core temperature rises, and you lose fluids primarily through sweat. Water is essential for several bodily functions that become stressed during a workout, including temperature regulation, joint lubrication, and nutrient transport. By drinking water consistently, you help your body manage these demands, preventing a cascade of negative effects that can impair your workout and endanger your health.

The Impact of Dehydration on Performance

Even mild dehydration can have a noticeable impact on your workout. A loss of fluids equal to just 2% of your body weight can lead to a 25% decrease in your endurance. This happens because dehydration causes blood volume to decrease, making your heart work harder to pump blood and oxygen to your working muscles. This increased strain can lead to faster fatigue, decreased stamina, and an elevated heart rate. Ignoring hydration can turn a productive cardio session into a struggle, limiting your ability to achieve your fitness goals.

The Risks of Ignoring Thirst

Many people rely on thirst as their only signal to drink, but this is a mistake, as thirst is often a lagging indicator of dehydration. Waiting until you feel thirsty means you are already in a state of fluid deficit. Continuing to exercise in this state can increase the risk of more serious health issues, including:

Heat injury: Exercising in a dehydrated state, especially in hot conditions, can lead to heat cramps, heat exhaustion, or the potentially deadly heatstroke.
Muscle cramps: Water and electrolytes are vital for muscle function. A deficiency can cause painful muscle contractions and cramping.
Cognitive impairment: Dehydration affects brain function, leading to impaired concentration, coordination, and decision-making, which can increase the risk of injury.
Rapid heart rate: With less fluid in your blood, your heart must pump faster to maintain adequate circulation, placing unnecessary stress on your cardiovascular system.

Creating Your Cardio Hydration Plan

Developing a smart hydration strategy is key to a safe and effective cardio workout. The right amount and timing can vary based on individual factors like sweat rate, workout intensity, and environmental conditions. Here is a general guideline to follow.

General Hydration Guidelines

Before Your Workout: Start your hydration process well before you begin exercising. The American Council on Exercise recommends drinking 17 to 20 ounces of water 2-3 hours beforehand, and another 8 ounces about 20-30 minutes before starting.
During Your Workout: Aim to drink 7 to 10 ounces of fluid every 10 to 20 minutes. For lower-intensity workouts, the lower end of this range may be sufficient, while higher-intensity or hotter conditions might require the higher end. Taking small, frequent sips is better than gulping large amounts at once, which can cause stomach discomfort.
After Your Workout: Replenish the fluids you lost to aid recovery. Weighing yourself before and after a workout can provide an accurate measure of fluid loss. For every pound lost, drink 16 to 24 ounces of water.

Water vs. Sports Drinks: A Comparison


Feature	Water	Sports Drinks	Considerations
Primary Function	Replenishes lost fluids, supports basic bodily functions.	Replenishes fluids, electrolytes (sodium, potassium), and carbohydrates.	The choice depends on workout duration and intensity.
Best For	Short, less intense workouts lasting under 60 minutes.	Extended, high-intensity exercise, or working out in hot, humid conditions.	For most daily cardio sessions, water is sufficient.
Carbohydrate Content	None	Contains sugars (carbohydrates) for energy replenishment.	Too much sugar can hinder hydration and cause stomach upset during exercise.
Electrolyte Content	None	Contains sodium and potassium to replace salts lost via sweat.	Essential for longer, more intense workouts where significant electrolytes are lost.
Hydration Speed	Absorbed efficiently by the body.	Can enhance fluid absorption, especially with a bit of sodium.	For shorter workouts, water is absorbed quickly enough.

Conclusion

To maximize your cardio performance and protect your health, you must drink water during your workout. Hydration is not a passive activity but an active part of your fitness routine that supports everything from muscle function to cardiovascular health. By following a smart hydration plan—drinking before, during, and after—you can prevent the dangers of dehydration, improve your stamina, and ensure a more effective and safer exercise session. Listen to your body, and don't mistake thirst as the only cue. Proper hydration is a fundamental strategy for anyone serious about their fitness.

How to Measure and Adjust Your Hydration

To fine-tune your hydration strategy, consider monitoring your fluid loss. The simplest method is weighing yourself before and after a workout. For every pound you lose, consume 16-24 ounces of fluid to recover. Another simple indicator is urine color: pale yellow urine indicates good hydration, while darker yellow suggests you need to increase your fluid intake.

Frequently Asked Questions

Yes, it is highly recommended to drink water while running, especially for runs lasting longer than 45 minutes or in hot conditions. Taking small sips every 15-20 minutes helps maintain hydration, prevent cramps, and support performance.

For a 30-minute session, you should aim to drink about 7-10 ounces of water every 10-20 minutes. For most moderate-intensity workouts of this length, plain water is sufficient.

If you don't drink water during cardio, you risk dehydration, which can lead to fatigue, muscle cramps, overheating, and reduced exercise performance. Your heart also has to work harder to circulate blood.

For most daily or short-duration cardio sessions, water is the best option. Choose a sports drink for high-intensity exercise lasting over an hour or in hot weather, as it helps replace electrolytes and carbohydrates lost through sweat.

Yes, drinking too much water too quickly can cause overhydration or hyponatremia, though this is rare. Symptoms include bloating, headaches, or disorientation. It's best to sip consistently rather than gulping large amounts.

A good indicator of hydration status is urine color; it should be pale yellow. If it's darker, you need more fluids. Another method is weighing yourself before and after a workout to monitor fluid loss.

Cold water is preferable during workouts as it can help lower your core body temperature, which improves exercise performance and is absorbed more quickly by your gut. However, room-temperature water is also fine for hydration.