Why Do I sweat So Much When I Run?

female runner wiping sweat after a running workout

“Why do I sweat so much when I run?”

If you’re looking for an answer, you have to the right place.

When I first took up running a few years ago, I relied on sweat as my main indicator of how hard I was pushing myself.

The more I sweat, the better and more accomplished I felt.

As I got fitter, however, I noticed that I’d started to sweat a lot more than before.

In fact, most of the time I ended up a sweaty mess by the end of my runs.

The profuse sweating scared me, as I thought there was something wrong.

Concerned,  I did what most people would do:

I Googled it.

To my relief, I found that I’d been worried over nothing.

In this post, you’ll learn the basics of what sweating is, why it happens, and how to deal with it if you’re concerned about it.

You’ll soon understand that when you’re a runner, sweating is your best ally and friend.

Sweating While Running Explained

Let’s break down the science of sweat.

Sweating is the natural process that regulates your core body temperature by keeping it as close to 98.6 degrees as possible.

When your body starts to overheat (for instance, while running), the nervous system activates the sweat glands to release perspiration, which is a water-and-electrolyte solution.

That in turn cools off the skin, resulting in a chain reaction of temperature reduction that eventually brings your core temperature down.

There are other forms of sweat that have nothing to do with heat regulation.

People sweat profusely when they’re nervous, or even as a response to spicy foods or hormonal changes.

Why Do I Sweat so Much When I Run – The Factors

Since every runner’s body is different, sweat rates vary from one person to the next.

The exact amount that you sweat is determined by a slew of factors including the number of sweat glands you have (between 3 and 5 million), outdoor temperature, resting body temperature, clothes worn, training intensity, fitness level, etc.

Generally speaking, the fitter you are, the more you’ll sweat.

The reason boils down to engine efficiency.

Fitter athletes tend to sweat more, and they start sweating a lot earlier in their workouts because their body’s thermoregulation system kicks into action faster.

That in turn helps them keep their core temperature down from the start of their session to the end.

Speaking for myself, I started noticing my increased sweat rate once I got serious about my running, doing lots of long runs and more intense interval workouts.

Nowadays I simply think of it as the price I pay for being fit.

What’s Normal Sweating?

Any amount of sweat is considered normal.

Everyone sweats a baseline amount at all times, even if you’re sweating more profusely than your training buddy.

The average person sweats between 0.8 to 1.4 liters, or 27.4 to 47.3 ounces per hour of exercise.

That’s equal to roughly one to three pounds of body weight.

Excessive Sweating While Running

If you still think you sweat too much, you probably do, especially if you sweat from a specific area of the body without engaging in any physical activity.

It may indicate hyperhidrosis, a common affliction marked by excessive sweating that affects roughly three percent of the U.S. population.

Hyperhidrosis is typically described as any sweating that obstructs normal daily activities.

People who have it may sweat up to four to five times the amount that other people do.

They also report sweating in cool environments for no obvious reason.

If this is your particular case, consult a doctor to discuss the treatment options available and to rule out any other underlying conditions.

Keep in mind that only a certified physician can officially diagnose such a condition.

Additional resource – What’s the best temperature for running

runner sweating while running on a trail

Why Do I Sweat So Much When I run – The Solutions You Need

Tired of dealing with sweat during your runs?

Try these simple solutions:

Measure Your Sweat Rate

Still don’t know whether you sweat more than normal?

Try measuring your sweat rate.

Doing so will help put your concerns to rest.

You do it by monitoring your pre and post-training bodyweight.

To begin, record your nude body weight before a run, then once you’re done, dry yourself immediately, strip down, and step on the same scale again.

The difference between your weight before and after your workout shows exactly how much fluid you lost.

For this to work, you need a digital scale, as it will show more detailed numbers (think 177.9 vs. 177).

Also, make sure your bladder and bowels are empty before stepping on the scale.

Record what and how much fluid you consumed during the run itself, as well as the weather conditions.

Your next step is to convert your sweat loss to ounces.

This tells you your fluid needs following a workout.

For each pound, you lost 16 ounces of fluid.

(or one liter of fluid for each kilogram).

For example, if you lose 2 pounds, your sweat rate for that particular session is 32 ounces.

This tells you that you need to drink that same amount to replace any fluid losses and stay well hydrated.


Now that you know how much you’re sweating when running, the next step is to replace the fluid losses.

To keep your body well hydrated, make sure to drink plenty of water before, during and after your runs.

For longer sessions, hydrate on the run.

Drink eight to ten ounces of water for every 15 to 20 minutes of exercise, and make sure to drink an extra eight to ten ounces of fluid within 30 minutes of finishing your run.

During your runs, you’re also likely losing lots of vital electrolytes through your sweat.

If you sweat profusely or run for extended periods of time in hot weather, make sure to take in some salt to make up for your electrolyte losses.

Additional resource – Sodium for for runners

Turn On a Fan

When running on a treadmill, turn on a fan, open a window, or lower the air conditioning to reduce humidity in the air.

Consider Medicating

Use an over-the-counter antiperspirant containing about 10 to 15 percent aluminum chloride, and don’t restrict your use to your armpits.

Antiperspirants can also help curb sweating when applied to the palms and soles of the feet.

Just keep in mind that some antiperspirants are prescription only, so consult your doctor for the best option for you.

Cool Off

Immediately following a run, take a cold shower (if possible).

Anything that lowers your core body temperature will help you stop sweating faster.

Keep It Tidy

Shaving your armpits removes hair that keeps deodorant and antiperspirants from getting to your skin.

It also helps decrease odor because your hair holds more bacteria than your skin does.

Dress Properly

Invest in summer-friendly running apparel.

That means going for lightweight, synthetic fabrics with ample ventilation that will pull sweat away from your skin to the outer surface where it evaporates.

This type of clothing allows heat to move away from the body.

Merino and bamboo are excellent options.

Here’s the full guide to cold weather running gear.

Watch Your Diet

Your diet can influence your athletic performance, your health, and your sweat rate.

Consuming certain foods, including caffeine, garlic, onions, and curry, can stimulate your sweat glands, making you sweat more than normal.

Making these simple tweaks to your diet might solve your sweat problems.

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There you have it! I hope today’s post offers a clear answer on the “Why do I sweat so much when I run” question.

If you have any concerns or questions, feel free to leave them in the comments section below.

In the meantime, thank you for reading my post.

David D.


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