You feel it the moment you enter the water. Your heart pounds, your muscles contract, your lungs tighten up! Fortunately, that feeling doesn’t last for long.

A few minutes later, you’ve moved beyond that initial hump of shock (and temperature change) and floated into a world where swimming freestyle is almost as comfortable as walking.

Water is nearly 800x more dense than air, and as they say, a body in motion stays in motion! Beyond the simple inertia, what’s actually happening inside your body as you move through the water? Let’s dive in and find out!

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Think of your body as a vessel. When you start your workout, every part of your body works together to move your vessel forward. Some body parts and energy systems work harder than others.

Your heart will begin to beat faster to pump blood to your muscles, while your stomach will slow down because digestion is no longer a priority.

What Happens To Your Body When You Swim?

When you’re exerting physical effort, your body tries to accomplish three main things:

• Increase Oxygen Flow
• Eliminate Metabolic Wastes
• Eliminate Heat


  • According to the American Heart Association, swimming is considered a great aerobic exercise.
  • Aerobic exercise enlarges the heart and increases blood flood through your entire body.


  • After 2 minutes of swimming, your body goes into aerobic respiration, which causes your heart rate to increase.
  • Your heart works to circulate oxygenated blood, and your heart rate increases to efficiently move the oxygen to your muscles.
  • Tracking your heart rate while you swim can be very beneficial to analyzing your performance in the water. With the MySwimPro app, you can analyze detailed reports on your heart rate for all your swims with a compatible smartwatch.


  • When you move, your body produces heat. Then your blood vessels dilate, which brings heat to your skin, and then is released.
  • This is why your skin feels warm when you work out, your body is getting all of that inner heat out!
  • This causes your body and face to turn red!


  • While swimming or strength training for swimming, you will experience micro-tears of your muscles.
  • You’ll need 24-48 hours to allow your body to recover and rebuild the muscle.
  • Swimming engages your total body!

Try these dryland workouts to get stronger!


  • While swimming, the pace of your breath will change, allowing your lungs to take in more oxygen.
  • Swimming can help increase your lung volume by increasing your VO2 Max, which is the maximum amount of oxygen you can use.
  • Over time as you get more fit, your VO2 max will get increase, therefor your lungs will become more efficient.


  • Your brain loves swimming. The extra blood and oxygen helps you become more alert, awake, and focused. It releases endorphins, the “feel good” hormones in our body.
  • There are scans of the brain that show it literally lights up in more areas even after a 20-minute walk. The same thing happens when you do any form of exercise including swimming!

How do you feel after swimming? Tell us in the comments!

For more tips like this, follow MySwimPro on YouTube!

Looking for swim workouts? Download MySwimPro, available on iPhone, Android and most smartwatches.  Sign up for MySwimPro Coach to unlock unlimited Swim and Dryland workouts, personalized Training Plans, analytics and more!



  1. After I swim I feel mentally at peace and energized at the same time. Even when I’m exhausted and I don’t “feel like” swimming, if I swim I ALWAYS feel better- it’s like magic!

  2. I had polio. One leg shorter. After swimming my back pain gone and any stiffness gone. Im 65 and im still working. I think the swimming does wonders for my blood circulation that is not normal. I dont think people understand the benefit of swimming.😃

  3. John Kraemer Common Ground Masters Elkhorn E on

    Have been coached by the same coach for 25 years as a masters swimmer. Craig Kersten has literally kept me alive physically and spiritually doing a tough 1 hour workout 3 days a week for that entire time.
    I start with a clean dive into the deep end and just let my streamline take me as far as I can.
    This amazing feeling sets the tone for the rest of the workout as I feel “one with the water”.
    There are sets that I think about cutting short but I dont and that gives me the mental toughness to tackle anything that could come my way during the day. The cool down is my hardest part because I am just starting to feel loose and don’t want it to end. Will get after it next time.
    The gang I swim with are fun, competitive and have become my best friends.
    Swimming is a very special activity that is hard to explain to a non swimmer.

  4. Swimming is my go-to exercise when my body aches from gyming, cycling, aerobic classes and generally overdoing things. It stretches my body, irons out all the kinks and, if you hold in your stomach, doesn’t hurt your lower back! There’s nothing better. But…..the hunger……wow – could eat a horse after a sea swim.

  5. Richard Burdyshaw on

    I swim for my health, and I is a wonderful workout. I ride a bike but for pure enjoyment the swim is a life lifting joy. At 70 I feel so alive in the water. Other activities I feel to grounded, in the water I feel as if I’m flying. Swimming gives a freedom of me myself alone and movement is easier. To your question. After a swim I might be a bit sore, however I still have energy, also I still have a spring in my step. Maybe most exciting is my out look on my life is so positive. I feel more alive and involved in my day or evening. Oh what a joy it is. Can you tell is just swam? Al good and no worry’s 😀

  6. After I swim, I take a shower. I feel more energized and more alert, refreshed. The hard part is usually getting there so I like to swim as part of my morning routine before giving myself time to think about whether I want to or not. Although after a long day usually stressful day at work swimming gives me a re-boost to be more engaged in evening activities such as making dinner, chores, studying, reading and playing video games [ 🙂 ].

  7. At 76 years of age I am grateful for the time I’ve taken over the years to swim for 45 minutes at least three times weekly. I wear snorkeling fins for greater resistance while moving back and forth in our local municipal pool. The support of water is in contrast to the strain of using gym equipment which would lead to aggravated lumbar issues.

  8. I just started a master’s swim class a week ago. I thought I would toss my cookies the first 300 meters. Lol. I am so so happy to have discovered these courses. I love it! I feel so at peace and so energized and accomplished after each 90 minute session. It’s a challenge that I am excited about. I plan to keep going, making sure nothing stops me.

  9. It’s my favorite formm of exercise. As I swim I go into a zone and daydream. When I use equipment such as a Nordic step machine or a stationary bicycle I just count the minutes and I can’t wait to get off.

  10. I really cannot explain but after an accident and had to have back surgery and having to take schedule drugs Five years ago on advice from surgeon said just swim swim swim when I started I could barely get across a 25 metre pool. Five years later no schedule drugs and fitter better body and swimming average 36 km per month freestyle back stroke breaststroke 74 years old and feeling great

  11. Kimberly Bull on

    I absolutely love swimming laps! It makes me feel great mentally, it is helping me get into shape very quickly! I am losing inches and weight and it is really helping my arthritis.I have 2 bone on bone knees and a torn ankle tendon. I can’t walk as far as I used to without being in pain but I sure can swim! For the first time, I am actually believing that the swimming is healing my body and I might je able to avoid multiple surgeries the drs say I need! I am really thankful. 🏊🏼‍♀️🙂

  12. Carol O'Reilly on

    Swimming is the only exercise I have maintained and keep going back to. I stand up straighter following my pre work morning swim with confidence money cannot buy and ready to face the world of finance.
    Nothing else has left me with the buzz I get from swimming and I have tried everything from Blaze to yoga and everything in between. The serenity of my time in the peace of the pool really sets me easily and unless you swim it is difficult to describe this degree of tranquillity.
    The side effects are benefits which include increase success on the golf course, toned and trim figure, bright eyes and skipping that 3pm wall… I would recommend swimming any day.

  13. I’ve just started swimming in the sea at 65
    Its freezing to start but you get used to it a good 20 minutes is fine I feel happy and energised I only go once a week but wish I had done it 50 years ago there is a lot of people my age and older go every day and love it even if it’s just for a dip they love it to cheers

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