Do You Sweat While Swimming?

I was in the gym change room after swimming a few laps of breaststroke when a woman looked at me wide-eyed and asked how I’d broken that sweat. She’d mistaken the drops of pool water on my skin for sweat. Or… was it sweat? Her remark got me wondering: do you sweat while swimming?

You do sweat while swimming. The amount differs depending on factors such as the weather conditions and water temperature and your sex, fitness level, and degree of exertion. However, you generally sweat less while swimming than while doing land-based exercise.

I’d always thought that swimming stopped us from sweating, not the other way round. But since it turns out our bodies do indeed lose water while we swim, should we be drinking water during swimming workouts to stay hydrated? How much do we sweat while swimming, and what does this mean for our health and fitness?

How Much Do You Sweat While Swimming?

I’m sure I’m not the only person who’s surprised to find out that you sweat while swimming. After all, you don’t see or feel the sweat when you're in the water.

The amount you sweat while swimming varies from person to person and situation to situation. Here's a glance at some factors that increase how much you sweat while swimming.

You Sweat More While Swimming In Warm Water

• Swimming in warm water raises your body temperature, increasing the amount you need to sweat to stay cool.

You Sweat More While Swimming On Hot Or Humid Days

• When it’s hot and steamy, the amount you sweat goes up. Your sweat rate can double when you exercise in hot or humid weather (compared to when the weather is fair).

You Sweat More While Swimming When You Exert Yourself

• The harder you push yourself while swimming, the more you sweat.
• So, while powering through laps of the most strenuous stroke, butterfly, you’ll sweat much more than while you’re floating on your back.

You Sweat More If You Wear A Wetsuit While Swimming

• The rubbery material wetsuits are made of (neoprene) traps heat, increasing your body temperature and sweat rate. Avoid wearing wetsuits in warm water.

Do Some People Sweat More Than Others?

Certain factors increase how much you sweat, whether you’re swimming or not.

If these factors apply to you, you’re more likely to be generally sweatier:

• Large body size
• High muscle mass
• High fitness level
• Hormonal fluctuations
• Anxiety

Men have also been found to sweat more than women.

How To Work Out Your Sweat Rate

Here's how to get an idea of how much you sweat while swimming: weigh yourself naked, swim for an hour or so, dry off, then weigh yourself naked again. For every pound you’re lighter, you’ve sweated out 15.4 fluid ounces.

There’s a catch, though: the calculation will only be accurate if you don’t drink anything or use the toilet in between your weigh-ins. Plus, you’ll need to repeat this procedure with various exercise intensities and in different water and weather conditions to get a better indication of your sweating rate while swimming.

Can You Dehydrate While Swimming?

You can sweat without knowing it while swimming, so you might not realize you need to drink more to top up your dwindling water levels. You won’t experience the same tell-tale signs that your water levels are getting low that you do while, say, running. But if you don't put back what you lose, your dehydration risk increases.

Of course, your chances of dehydration are higher the more you sweat. So you’re most likely to become dehydrated during strenuous or long swimming workouts in warm water on hot or humid days.

If you’ll be doing high-intensity exercise, it’s best to swim in water temperatures that are 82 degrees F and cooler. For leisurely laps, water temperatures below 88 degrees F shouldn’t push your sweat glands into overdrive. Swimming in water that’s warmer than 90 degrees F ups your chances of becoming dehydrated.

On scorching hot or very humid days, stick to a quick splash in the pool.

How Can You Tell If You’re Dehydrated?

Think that only drinking when you're thirsty will keep you hydrated? Apparently not. Feeling thirsty means you're already dehydrated. Another way to tell you're dehydrated is by looking at your urine. It should be pale yellow. You're dehydrated if it's dark yellow (or strong smelling).

Other dehydration symptoms are dizziness or light-headedness, tiredness, dry mouth, lips and eyes, and urinating fewer than four times a day.

Watch out for these signs of severe dehydration (and if you experience them, see a doctor urgently):

• Extreme exhaustion or confusion
• Dizziness when you stand that doesn’t go away
• Not urinating for eight hours or more
• A weak or rapid pulse
• Loss of consciousness
• Seizure

Does Dehydration Affect Your Swimming Performance?

Not only can dehydration cause serious health trouble like urinary tract infections, kidney failure, and dropped oxygen levels in your body, but it can also stop you from swimming at your best.

Even mild dehydration can tire you out quicker, make you slower to respond, and increase your chances of injuries and muscle cramps.

Do You Need To Drink Water While Swimming?

For swimming success (and overall well-being), you need to hydrate before, during, and after you dive into the water.

Keep checking your urine (remember: it should be light yellow) to ensure you're beautifully hydrated before starting your water workout.

Drink about 16 fluid ounces of water a few hours before your swimming sesh, keep sipping while you swim, and drink some more water after you're done.

A popular guideline is to drink 4 to 6 fluid ounces every 15 to 20 minutes you exercise (or about 16 to 20 fluid ounces every hour).

When you’re properly hydrated, it’s easier for your muscles to grow and recover, your joints to stay lubricated, and your body temperature to be regulated – actually, your whole body works better.

Do You Need To Take Electrolytes While Swimming?

Electrolytes are minerals that do essential jobs in your body, like helping your nerves and muscles work well, maintaining a healthy pH balance, and keeping you hydrated. You lose electrolytes in sweat, mainly sodium and chloride. Though healthy eating (including lots of fruit and veggies) should restore your balance.

If you’re swimming just for fun or exercising for less than an hour, plain water can keep you hydrated.

However, you’ll probably need a boost from an electrolyte-enriched drink during strenuous or very long (more than two hours) training sessions, especially if the weather’s very hot or humid.

After a tough workout, you could drink water and eat a sodium-rich snack, like salted nuts, pretzels, dill pickles, or crackers.

Summary

Although you don’t see or feel it, you do sweat while swimming, especially when it’s hot and you’re pushing yourself hard.

You probably won't get as sweaty as you do while exercising out of the water. Still, the same rules for staying hydrated apply to all forms of exercise, including swimming: drink water before, during, and after working out. So, have a water bottle within reach whether you're on the treadmill or in the pool!