Why Does Swimming Make You Tired? Here’s 6 Reasons Why

Swimming is an amazing workout! It has a long list of benefits that range from physique to health and everything in between. It’s this miracle workout that not only works your body, but is also gentle enough on your joints that makes it great for anyone.

As a college athlete myself, I’ve encountered a wide variety of workouts. You name it, we probably did it in our off season. From sprints and running timed miles to basketball drills and HIIT workouts, there were very few things that left me as tired as swimming laps.

There’s just something about it that leaves you knowing that you’ve gotten a great workout. You don’t even need a lot of time to achieve this. But have you ever stopped and thought about why?

Why Does Swimming Make You Tired?

If you break it down, there are lots of different reasons swimming can make you tired. From the workout to fueling your body beforehand, we’re going to look at the biggest reasons you are feeling exhausted while swimming. Not only that, we’re also going to look at what you can do about each of these reasons why swimming makes you tired.

It’s one thing to understand why it makes you tired, but it’s a whole other thing to learn what you can do about it, and that’s what we’ll be doing here.

Swimming is a Full Body Workout

Why Does Swimming Make You Tired

Foremost, swimming makes you tired because it is simply hard work. When you compare it to other cardio workouts, it’s hard to find one that can truly compare. If you’re cycling, you’re using a lot of leg muscles. If you’re running, you’re using legs and core. But, with swimming, you are literally using your entire body.

As we’ve shared before in a previous article, it can work up to 50 muscles at a time. From your trapezius muscles at the top to your soleus muscles near your ankles, your body works incredibly hard to keep you moving through the water.

Think about it. To stay afloat, you’ve got to use your arms and your legs to propel you properly. And because you’re kicking your legs and moving your arms, all of your core has got to be strong to move in a forward, straight line. It all comes together, and the result is an incredible workout that can leave you feeling exhausted.

So, what can you do about the fact that swimming is a full-body workout? Well, there are a couple of things to think about. If you are feeling wiped out after your swim session, consider slowing things down or building up your endurance a little more.

Like I said above, it’s a big workout, so a little can go a long way. If you’re noticing that you are struggling to function after your morning swim, maybe taper down the workout and then work your way up. Slow and steady wins the race, especially with swimming!

Another thing to consider if you’re getting tired quickly with your swims because it’s a full-body workout is to strengthen your weaker muscles. Incorporate some cross training and pinpoint your weaker areas. For me, my quads and legs are much stronger than my upper body. So, I would consider incorporating some arm strength training to help me endure these amazing full-body swim sessions!

Swim Workout Intensity

Why Does Swimming Make You Tired

Swimming is intense! You can burn some serious calories by jumping in the pool and pumping out a good workout. To be more specific, the average person could burn up to 500 calories per hour!

Let’s put that in perspective for you. The average jogger at a conversational pace burns around 400 calories per hour. In order to burn over 500 calories per hour for running, you’d have to keep a pace of around 6 minutes per mile! I don’t know about you, but I won’t be running 6 minute miles for an hour straight! If I want something intense that will burn a lot of calories, I’m going to stick with swimming!

But what if it’s too intense for you? What if you think that the intensity may be making you too tired? Well, the simple thing you can do about that is to lower the intensity. Take more breaks between laps. By allowing your body longer recovery times between sessions, it can definitely make a difference.

Another thing you could do to lower the intensity of your swim workouts is to slow your pace. As we said above, swimming is already a full-body workout. If you’re feeling completely worn out, there’s absolutely nothing wrong with slowing your pace for the time being.

Pool Water Temperature

Why Does Swimming Make You Tired

Believe it or not, the pool water temperature can also play a role in why swimming makes you tired. Most people would assume that cold water temperatures would make you more fatigued because it lowers your body’s core temperature, and it has to work even harder to warm the body up. But, in actuality, you can become fatigued in both colder water temperatures AND warmer water temperatures.

Swimming in warm waters can also lead to exhaustion just as quickly as swimming in waters that are too cold. Not only does warmer water, around 90 degrees, increase your chances of exhaustion, it also increases your chances of dehydration (which we will address later).

So, if you notice that your pool water is too cold or too hot, it may contribute to the reason swimming is making you tired. With swimming in water, you need to think about it in terms of “Goldilocks and the Three Bears”. You don’t want water that is too hot or too cold, you want the water temperature to be just right. For the highly competitive swimmer, the ideal temperature is between 77 and 82 degrees. For swimming in an environment that is more recreational or simply for a fun workout, they suggest closer to 85 degrees.

The biggest thing you can do if you feel that the temperature of your pool is affecting your energy levels is to communicate with the maintenance staff to understand what they typically keep the temperature at. Of course, that is only if you workout at an indoor pool facility. If you are swimming in open waters or an outdoor swimming area, consider a workout in an alternate swimming location if the weather is getting too hot or too cold.

Dehydration While Swimming

Why Does Swimming Make You Tired

Sounds a little ironic, right? You’re literally working out in water. It almost seems silly that you could get dehydrated. But just because you’re in a pool doesn’t mean that your body is going to stay hydrated. It’s not like you’re drinking the pool water, so of course you can become dehydrated while swimming!

So another answer to the question of “why does swimming make you tired” is dehydration! It’s actually a little more complicated than your average workout, like running. When you’re running, you will get hot and feel yourself sweating. But, in the water, it’s a different story. Because you’re in cool water, you don’t realize your body is sweating or heating, but it is. And whenever your body is working hard, sweating, or raising your body temperature, it’s going to need hydration to keep working properly.

The reason that dehydration is on our list is that one of the big signs that you need water is tiredness and fatigue. So, if you notice that swimming makes you tired (or more tired than you would normally be), definitely consider what you are doing to stay hydrated.

What you can do about hydration? Well, obviously you can drink more water. But that’s a little vague for advice. More specifically, you can help prevent dehydration and exhaustion by coming to your swim session fully hydrated. If you’re doing a workout first thing in the morning, make it a goal to drink an entire bottle of water on your ride there. If you’re planning to swim later in the afternoon, attempt to drink only water and have it consistently throughout the day.

Other than hydrating beforehand, you can make sure that you have water easily accessible. If you are at a pool, you can keep a water bottle within arm’s reach to sip on between laps. If you are in open waters, it may be a little less convenient, but it should still be a priority, especially if the open water you’re swimming in is warm, and the sun is out.

Swimming in the Sun

Why Does Swimming Make You Tired

Speaking of swimming in the sun, this can not only increase your chances of dehydration, it can also increase your level of tiredness after a good swim workout.

In general, being in the sun can make you tired. From the heat it generates in your body to the UV (ultraviolet) rays that can lead to chemical changes in your body, it brings exhaustion.

If the sun alone makes people tired, can you imagine how tired one must be after doing a full body, fully intense swimming workout in the sun? Yeah, you’d definitely feel like you need a nap.

What you can do about the sun and its effect on your level of exhaustion? If you only have access to an outdoor pool, then there may be less that you can do than if you have access to an indoor pool. However, there are still things you can consider.

If you are swimming outside, think about swimming when the sun isn’t at its highest. For example, you could swim earlier in the morning or later in the evening instead of swimming right in the middle of the heat of the day.

But, of course, if you have access to both an indoor and an outdoor pool, you could easily choose to go to the indoor pool on days when it is especially sunny and hot to avoid over exhaustion.

Lack of Nutrition Before Swimming

Why Does Swimming Make You Tired

For our last reason why swimming makes you tired, we’re going to look at nutrition. Similar to hydration, nutrition is really important on the prep side of your workout as well as when you are actually doing your workout.

In our article on How to Freestyle Without Getting Tired, we touched on a few more things to consider if you don’t want to get too tired. And one of those was nutrition. In order to swim at your best without getting overtired, you’ve first got to make sure you’re fueling your body properly with lean proteins, fruits, and vegetables.

But you’ve also got to make sure that you are fueling yourself before your workout and during (if you will be swimming for an extended amount of time). While some people prefer working out on an empty stomach, others may find that it leaves them feeling extremely exhausted and fatigued. If you are feeling this way, make it a priority to eat a healthy pre-workout snack. Prioritize your nutrition and your performance and energy will follow!


In this article, we broached the question – why does swimming make you tired?  We touched on 6 ways that swimming makes you tired and what you can do about them. 

First swimming is a full-body workout.  Your upper body, your lower body and your core are all cranking at the same time (tip: don’t do too much too soon)!  The second way swimming can make you tired is your swim workout intensity (tip: slow your pace if you need to).  Did you know you can burn more calories swimming laps than even running a 6 minute pace for an hour?  The third way is if the pool water temperature is either too cold or too hot (tip: you want it between 77 & 82 degrees). 

The fourth way swimming makes you tired is by becoming dehydrated (tip: drink before and during your workout).  Number five in our list is swimming in the sun (tip: swim indoors in the morning or late afternoon).  The sixth way swimming can make you tired is by not eating a snack or small meal before your swim workout (tip: grab something to eat).  So there are our six reasons (and solutions) to why swimming might be making you tired!

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Jessica Meacham

I’m a former college athlete turned marathon-running and outdoor exploring mom of two little ones. From hiking through Iceland to paddle boarding in Lake Tahoe, our family is always up for a fun adventure that incorporates fun and fitness!

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