What Muscles Does Swimming Work? 4 Strokes Examined

Many runners and cyclists dream about completing a triathlon

Perhaps you are a runner who has experienced an injury from your main sport, spent quite a number of weeks cross-training by cycling and swimming, and feel compelled to put your hours in the gym to the test once you’re back to running with a stab at a triathlon.

Or, perhaps you’re a cyclist who’s always enjoyed running and feels like training for a triathlon would be a perfect opportunity to get to focus on more of the activities you enjoy in your workout routine.

Even though swimming can be challenging, it is a fantastic total-body workout, and sticking with it will help you improve your cardiovascular fitness and strengthen most of the major muscles in the body.

But what muscles does swimming work? Can swimming strengthen your back? Arms? Legs? In this article, we will discuss the most important swimming muscles and how the different swimming strokes affect the muscles used when swimming.

We will cover: 

  • Why Is Swimming So Hard?
  • What Muscles Does Swimming Work?

Let’s jump in!

Someone swimming the front crawl stroke.

Why Is Swimming So Hard?

Even if you have good endurance and are well-trained in another aerobic activity, many people find swimming to be quite challenging. 

Many well-conditioned endurance athletes find that they seem breathless while swimming and that the activity is not just a hassle— changing into a bathing suit, getting wet, waiting for a lane, showering—but sort of defeating. You are panting by the end of a few laps.

Although some of this comes down to technique and learning how to breathe properly while swimming, much of the challenge that novice swimmers experience is due to the fact that swimming works a lot of muscles in your body, some of which may not have the strength and endurance you are accustomed to for other activities.

For example, runners and cyclists tend to develop great lower-body strength, but the muscular strength and endurance in your shoulders, arms, upper back muscles, and lats may be relatively weak.

Someone swimming the front crawl stroke.

If you hop in the pool and expect to be able to swim for 20 or 30 minutes doing the front crawl, you will likely find that your upper body and back muscles used in swimming will be burning or fatigued after just a handful of laps.

However, sticking with a consistent swimming training plan can help you become fitter, stronger, and more capable in the pool, and the muscular strength you develop can transfer to other sports as well.

So, swimming works which muscles, you ask? Let’s take a closer look.

What Muscles Does Swimming Work?

The muscles used in swimming are somewhat dependent on the swimming stroke.

Although all swimming strokes work many of the same muscles to some degree—such as the latissimus dorsi in the back and the deltoids in the shoulders—the different strokes will target the muscles used when swimming to different degrees.

Therefore, let’s break it up by stroke:

Someone swimming the front crawl stroke.

Muscles Used for Freestyle and Backstroke

Here are the muscles worked by the front crawl or freestyle, and backstroke:

  • Core muscles: The core muscles and obliques along the sides of your torso help support the trunk rotation you need as you propel one arm into the water while the other arm comes out of the water.
  • Hip Flexors: The hip flexors, like the iliopsoas, are used when swimming to help your legs provide a steady and powerful kick, hinging at the pelvis for full leg propulsion.
  • Sternocleidomastoid: We often don’t think about the muscles in the neck, but swimming works muscles in the neck, such as the sternocleidomastoid. This muscle helps us rotate the head to one side to breathe during the front crawl.
  • Hand and Forearm Muscles: The front crawl stroke or freestyle works several muscles in your hands and forearms as you pull the water towards your body to provide forward propulsion. Examples include the thenars (hand muscle), the brachioradialis, and the flexor digitorum profundus in the forearms.
  • Arm Muscles: Almost every stroke in swimming uses arm muscles like the biceps and triceps. With freestyle, these muscles help pull the water towards the body to promote forward propulsion.
Someone swimming the back stroke.
  • Deltoids and Rotator Cuff Muscles: The deltoids in the shoulders, along with rotator cuff muscles like teres major and minor, help rotate the arms and lift the arms in and out of the water, helping to angle the hands in the proper position to function like paddles.
  • Chest and Back Muscles: Numerous muscles in the chest and back are used when swimming the crawl stroke and backstroke.
  • Trunk Muscles: Trunk muscles worked by swimming these strokes include the pectoralis major and minor in the chest, serratus anterior, and back muscles like latissimus dorsi, trapezius, rhomboids, and erector spinae. 
  • Back Muscles: The upper-back muscles help stabilize the shoulders and provide the arm drive for propelling the body through the water. Other muscles in the back help stabilize the spine as the trunk rotates with the unilateral arm movement during the swimming strokes.
  • Glutes and Legs: Swimming uses the muscles in the hips, groin, glutes, legs, and feet. These muscles are necessary for providing a strong and powerful kick. They include the adductors, gluteus maximus, gluteus medius, gluteus minimus, quads, hamstrings, calves, tibialis anterior (shin muscle), and flexor digitorum brevis (foot muscles).
Someone swimming the butterfly stroke.

Muscles Worked During the Butterfly Stroke

The butterfly stroke is arguably the most challenging and metabolically- and muscularly-demanding swimming strokes. 

This stroke uses many of the same muscles worked during the crawl stroke and backstroke, but the muscles are working in different ways to facilitate different movement patterns.

For example, the abdominal muscles and lower back muscles in the core work together to help lift the trunk and upper body out of the water when breathing.

The glutes fire powerfully and explosively to provide a strong dolphin kick to propel the body forward and counterbalance the upper body coming out of the water.

The deltoid, rotator cuff muscles, chest muscles, upper back muscles, and arm muscles are used when swimming butterfly to drive the upper body up out of the water and then under to pull the body forward.

This stroke is very demanding on the upper back, shoulder, and arm muscles.

The quads, hamstrings, and calves also play a role in providing that powerful dolphin kick.

Someone swimming the breast stroke.

Muscles Worked During the Breaststroke

Many novice swimmers think of the breaststroke as an “easy“ stroke or a relaxing stroke, but if you swim quickly, the breaststroke can also provide a great cardio workout.

Moreover, because you are working against water resistance, this stroke strengthens your muscles just as much as any other stroke. In fact, one of the benefits of breaststroke is that it challenges the muscles to work more in the frontal plane of motion, building strength and stability in your shoulders and hips.

Most exercises, such as running, cycling, and even swimming strokes like backstroke and cross stroke, take place in the sagittal plane with primarily motion in the forward and backward direction.

This can lead to weakness with side to side movement patterns, which is why incorporating lateral training or frontal plane exercises is so critical to developing well-rounded strength in your joints and muscles.

The breaststroke uses many of the same muscles as all of the other swimming strokes, but because you are sweeping your arms and legs against the water side to side, you work different muscle fibers.

The pectoralis major and minor and latissimus dorsi muscles help sweep the arms inwards and outwards against the water.

Someone swimming the breast stroke.

The primary leg muscles used to power the breaststroke frog kick are the quads, glutes, and hip rotators like gluteus medius and piriformis.

Keep in mind that every swimming stroke pretty much provides a full-body workout, but you can also target just your upper-body or lower-body muscles by using different swimming tools.

For example, you can use a kickboard to work your glutes, hamstrings, calves, quads, shin muscles, and muscles in the feet by doing either a flutter kick or butterfly dolphin kick.

A pull buoy can be used to target just your upper body, working the muscles in your core, back, shoulders, and arms.

Remember, although swimming in a pool at your local YMCA or gym can be intimidating if you’re not accustomed to swimming, you have so much to gain by adding swimming to your workout routine.

You will not only improve your cardiovascular fitness, but you will also work almost all of the major muscles in your body, helping develop well-rounded strength. 

However, with training, even beginners can master the basic swimming techniques and get a fantastic total-body workout.

Are you looking into learning how to swim, or are already a swimmer? Either way, we have some swimming workouts for you to try out on your first, or next trip to the pool. Check out our guide: The 3 Best Swimming Workouts To Get Toned to get started right away!

A lap swimming pool.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, and contributes to several fitness, health, and running websites and publications. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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