How Long Should I Swim To Get A Good Cardio Workout?


a swimmer working out in the pool

It is important to know how long you should swim to get a good cardio workout, particularly if your time in the pool is limited or if you have specific fitness goals.

Swimming is one of the best cardio fitness activities and will get your heart and lungs working hard in no time, particularly if you are a beginner.

As a general rule, at least 30 minutes of continuous swimming at least three times a week is needed to guarantee a cardiovascular fitness improvement in 8 to 12 weeks. As a beginner, you may see improvements in stamina in as little as 15 minutes of exercise in the beginning.

In this article, I will look at:

  • What is cardio fitness?
  • What is the heart rate zone?
  • Is swimming a good cardio workout?
  • How long should I swim to get a good cardio workout?
  • How long will it take to see results from swimming?
  • The best swim workouts for cardio fitness
  • How can I measure my fitness progression?

What Is Cardio Fitness?

Cardio fitness is a measure of how well your heart and lungs use and deliver oxygen-rich blood throughout your body during activity.

Any activity that gets your heart pumping and your lungs breathing heavily is considered a cardiovascular exercise. For example, walking, running and swimming can all get your lungs working hard.

Characteristics of a good cardio workout involve: [source]

  • An activity that is rhythmic and continuous, such as swimming, where you start moving and repeat the motion for a period of time.
  • An activity that gets the heart and lungs working harder.
  • An activity that uses the larger muscles in the body, such as the legs.

With better cardio fitness comes a range of health benefits, such as:

  • More energy overall
  • Better stamina
  • Reduced blood pressure
  • Improved cholesterol
  • Weight loss due to extra calorie burning.

It is important to note that although intense cardio activities are great to challenge the body and get the heart and lungs working well; they are not necessarily safe for everyone. Pushing your heart too hard can be extremely dangerous for some. Therefore, before starting a new cardio workout, it is important to understand your heart health and consult with your doctor.

To learn more about training for cardiovascular fitness, the University of Colorado Hospital has put together this fantastic informational leaflet which covers some of the most important concerns and questions.

What Is The Heart Rate Zone?

To improve your cardiovascular fitness, you need to raise your heart rate to a certain level, and keep it there for at least 20 minutes. According to research, you should work within 50%- 75% of your maximum heart rate. This heart rate level is your ‘target heart rate zone’. [source]

Heart rate zones are based on your maximum heart rate and are an indicator of how hard your heart is working.

With heart rate monitors becoming a standard feature of most new fitness smartwatches and trackers, it is much easier to see what your heart is doing and what you should aim for to get fitter, faster.

By working in your target heart rate zone, you can determine just how intensive the workout is and ensure you are raising your heart rate to a safe yet good fitness level.

Your target heart rate will depend on your age and fitness level, and you can use the following chart from the Brigham and Women’s Hospital to determine your target heart rate.

For a more detailed target heart rate chart, which breaks down a target heart rate by training intensity, the following article covers this in much greater detail, “Target Heart Rate Calculator Chart”

Again, it is important to note that pushing your heart too hard can be extremely dangerous for some. Therefore, before starting a new cardio workout, it is important to understand your heart health and consult with your doctor. This article is not medical advice.

Is Swimming A Good Cardio Workout?

Swimming is a fantastic cardio workout as it gets the heart and lungs working.

Being rhythmic and continuous, while working all the major muscle groups in the body, swimming regularly will dramatically improve your cardio fitness.

If you find you are not working hard in the pool or breaking a sweat, then perhaps you can increase the level of intensity of your swims to get the best cardio workout you can.

To increase the level of intensity in the pool, you can start by:

  • Taking shorter breaks between laps
  • Deliberately trying to swim faster.
  • Increasing your level of kicking, for example, shift from a 4-beat to a 2-beat kick.
  • Using training aids such as hand paddles which will increase the stamina of your muscles.

How Long Should I Swim To Get A Good Cardio Workout?

As a general rule, at least 30 minutes of continuous swimming at least three times a week is needed to get a good cardio workout and guarantee a cardio improvement over 8 to 12 weeks. Therefore, if you take breaks regularly on the pool wall, ensure you swim long enough to get at least 30 minutes of actual swimming done.

If you are completely new to exercise, you may start seeing increases in fitness and stamina from as little as 15 minutes of swimming, but as your body adapts, it is important to progressively increase your time to aim for a minimum of 30 minutes.

Most studies agree that 30 minutes, 3 times a week, is the most effective way to see a cardio improvement in 8-12 weeks. [source]

If you are more advanced, and are working out for longer, or want to push your fitness level, then integrating some interval training is a great way to level up.

Using interval training, you can swim at full pelt for a 60 to 90-second duration, with a 2-minute recovery between spurts.

I came across this concept of interval training, also known as HIT (High-Intensity Training), in a book called “Fast Exercise” by Dr Michael Mosley.

In summary, according to Dr Michael Mosley, you can exercise (i.e. swim) for as little as 10-minutes a day, 3 times a week with exceptional fitness results.

If you are struggling to fit fitness in, then this can be a great shortcut to getting the same results.

The details of how to achieve this level of fitness through short bursts of High-Intensity Training (HIT) is outlined in Dr Michael Mosley’s book, Fast Exercise, which I 100% recommend if you are serious about understanding and improving your fitness levels.

Fast Exercise: The simple secret of high intensity training: get fitter, stronger and better toned in just a few minutes a day

How Long To Build Cardio Fitness From Swimming?

Typically, with a regular swim routine, you will see fitness benefits in 8 to 12 weeks, and sometimes even sooner if you are consistent.

Depending on your starting level of fitness, you may even see cardiovascular fitness improvements from as little as two weeks.

How long it takes to get fit will depend on a variety of factors, but the area of HIT (High-Intensity Training) as mentioned previously, is getting great praise from researchers as a reliable and fast way to build cardio fitness.

A particular piece of research investigating the effects of HIT (High-Intensity Training) versus Moderate-Intensity Continuous Training (MICT) found that HIT is far superior in improving heart rate variability and is a time-efficient way to improve your cardio fitness. [source]

I am a big advocate of HIT exercise as a way of exercising effectively in a short period and HIT can be done in the pool through swim sprints.

To learn more about HIT and get all your questions answered by a medical professional, check out this FAQ page from Dr Michael Mosley on the subject or read his excellent book, Fast Exercise.

The Best Swim Workouts For Cardio Fitness

As with all exercise, where you start will depend on your current level of fitness.

I know it is tempting to dive in and try to knock it out of the park on day one, but if you do not do regular exercise, it is important to ease yourself into a new routine.

In the early days of starting any swimming routine, it is more important that you show up and build the habit of going to the pool than actually trying to set personal bests on day one.

Many of us, myself included, can fall into a pleasant swim routine and cover a set distance every week at a set pace.

Although this is wonderful, if you want to push your fitness levels, you will need to progressively increase the swimming challenge. Otherwise, our bodies will adapt to our current swim routine and stay at our current level.

This is one of the many reasons millions of swimmers every day wonder why they are not losing weight, despite swimming miles and miles. If they swim at a continuous low intensity, they will not lose weight.

From my research and particularly what I have learned from Dr Michael Mosley, to get the best swim workout that will help you lose weight and advance your cardio fitness, you need to turn up the intensity.

Of course, if you are unfit, overweight or have a history of heart disease, diabetes or stroke, it is best to see your doctor and seek professional medical advice before starting any high-intensity exercise as HIT gets your heart working hard.

Here is an example of a high-intensity swim workout that takes less than 10 minutes to complete. [source]

  1. Start with a gentle warm up by swimming slowly up and down the pool for 2 minutes.
  2. Gently increase the intensity to a moderate pace.
  3. When you are ready, swim 25 meters (typically one pool length) as fast as you can.
  4. Rest and swim a couple of more gentle lengths.
  5. When ready, do another one pool length sprint.
  6. Rest.
  7. Complete 4 sprints in total if you can, with rests in between.
  8. Finish with another 2 minutes of gentle swimming to warm down.

To learn more about how long you should swim, I have covered this in more detail in this article, How Long Should I Swim For? Times, Distances & Weight Loss Goals.

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How Can I Measure My Fitness Progression?

If your aim is to get a good cardio workout from your swims, it can be very rewarding and motivating to measure your fitness progression.

There are some very common tests that you can do to measure your cardio fitness, which are listed below.

Of course, with the surge in fitness trackers and health apps, monitoring your heart health has become much easier to do.

(As a side note, I just bought a very affordable fitness tracker called the AmazFit Band 5 for just £29.99 from Amazon to replace my FitBit that has an excellent heart rate monitor and is brilliant for tracking cardio fitness. I am so impressed with this tracker, which is also suitable for swimming. I thought it is worth a shout out if you do not already have a fitness tracker)

1. Resting Heart Rate

By exercising regularly, you should start to see your resting heart rate fall.

Resting heart rate has been shown to be a good indicator of future health. Studies have shown that those with a resting heart rate of over 70 have a greater risk of heart attack and hospital admissions.

Some elite athletes can have a resting heart rate as low as 40 BPM (beats per minute.)

Michael Phelps reportedly had a resting heart rate as low as 38 BPM when he was at his peak. [source]

Just measure your heart rate when you are at rest to get an idea of what yours is. Here is a full guide from The British Heart Foundation on how to measure your heart rate.

2. VO2 Max

VO2 max is a measure of your aerobic fitness.

The most reliable way to have your VO2 max measure is in a lab, but there is a way to work it out at home by using this formula:

VO2 Max = 15.3 x HR Max/HR Rest

  • HR Max = maximum heart rate
  • HR Rest = resting heart rate

You can then use the standard charts to find your aerobic fitness level. Here is a good reference that covers everything about VO2 Max, including charts.

You should start to see improvements in your VO2 max levels in as little as 6 weeks by using a HIT workout routine. [source]

Final Thoughts

Swimming is a wonderful cardiovascular workout and we swim lovers are blessed that our sport is one of the best around for aerobic fitness.

Tracking my cardiovascular fitness is a great way to stay motivated in addition to reassuring me that I am doing enough to main my heart health.

Our hearts are very precious things that need care and attention. Regular swimming at a good level of intensity can keep us happy and healthy.

Happy swimming!

Louise Byrne

Hi, I am Louise and I am obsessed with swimming. I spend my free time in the water or getting ready for my next water adventure.

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