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!

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5 thoughts on “6 Things That Happen To Your Body When You Swim

  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. 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.

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