Does Swimming Build Muscle? (Here’s Why It Doesn’t)

Many fitness magazines label cardio activities like swimming as muscle-building exercises. But it’s typically uninformed journalists meeting their article quota for the week publishing poorly researched content. So I’m here to set the record straight.

While swimming works the entire body and water provides more resistance than air, it does not build significant muscle mass. There is little resistance, a short range of motion, and no eccentric muscle action creating little stimulus to grow muscle.

Let me expand on this further.

Does Swimming Build Muscle?

Like all new activities, swimming will build muscle initially. But not to any significant degree. You must lift weights to maximize muscle growth. While water provides more resistance than air, it doesn’t offer enough resistance to maximize mechanical tension, which is a key driver of muscle growth ^[1][2][3].

Mechanical tension is maximized through force generation and stretch. In other words, heavy loads through a full range of motion. But you can also use light loads if sets are taking close to or to failure ^[4].

Swimming is a concentric-only exercise, so it does not have a stretch phase during the exercise. It’s like performing hundreds of straight-arm pulldowns but only the downward portion.

While concentric-only exercise does promote muscle growth, eccentric muscle actions are required to maximize the muscle-building response ^[5].

But there’s another problem with swimming to build muscle at the molecular level. Swimming is an endurance activity, and endurance exercise activates the AMPK pathway to promote endurance adaptations ^[6].

The molecular pathway we want to signal is the mTOR pathway which promotes muscle growth. The AMPK pathway inhibits the mTOR pathway. It lasts up to 3 hours and is influenced by the intensity and volume of swimming ^[6][7].

Therefore, swimming is not a good activity to build muscle.

Why Do Swimmers Look Muscular?

Some elite swimmers look muscular. Michael Phelps is a prime example. But we need to put this in perspective.

Firstly, he’s the elite of the elite level athlete, making him a complete outlier. Further, swimmers typically have low body fat making them look ripped and muscular.

Thirdly, swimmers train in the gym as part of their land-based training to get stronger for the pool.

And finally, swimmers like Michael Phelps may look muscular compared to other swimmers. But compare him to athletes like wrestlers and Weightlifters; there’s no comparison.

What Muscles Does Swimming Work?

Swimming is a nearly full-body workout. Freestyle targets and legs and glutes through hip flexion and extension.

For the upper body, the lats are the dominant muscle group pulling you through the water. During breaststroke, the legs work in a frog motion targeting the hips, and the arms and lats are worked in the upper body.

You’ll know which muscles are being worked as they burn quickly as you get through your laps in the pool.

Best Swimming Stroke To Build Muscle

There is no best swimming stroke to build muscle. They are all inferior to lifting weights for muscle growth.

This includes freestyle, breaststroke, backstroke, and butterfly. If you make swimming your primary activity to build a muscular physique, you’ll be sorely disappointed.

Does Swimming Build Leg Muscle?

Swimming works the legs vigorously but doesn’t build them. The hip flexion and extension range of motion is too short with little resistance. There’s a reason swimmers aren’t known for their muscular legs.

Instead, you must perform squat, lunge, and deadlift variations and progressively overload to consistently challenge the muscles and grow big legs.

Does Swimming Build Arm Muscle?

Swimming significantly works your arm muscles but won’t build them. There is little arm bend, and arms are built with elbow flexion and extension, also known as curls and extensions. Biceps curls and triceps extensions are what you need to develop arm muscles.

Does Swimming Make You Stronger?

Swimming develops strength specific to swimming. Meaning you likely won’t be able to lift more weight in the gym, but you’ll be stronger at pulling yourself through the water.

Strength is specific to the task, but general strength in the weight room transfers to many other activities.

Swimming strength doesn’t transfer too much else out of the pool.

Does Swimming Build Muscle Or Burn Fat?

We’ve established swimming doesn’t build muscle. But it also doesn’t burn significant body fat. That’s because losing body fat is a function of consuming fewer calories than you burn. Swimming is a way to create this caloric deficit since you’re expending energy.

If you don’t change your diet and start swimming, you’ll likely lose weight. This is why most people label swimming a fat-burning activity.

However, at some point, you must reduce your food intake to maintain the caloric deficit; otherwise, you will swim 7 days a week for hours to make up for it.

Can You Get A Six Pack From Swimming?

You can get a six-pack from swimming as six-pack abs are a function of low body fat. Swimming is a simple way to create a caloric deficit through energy expenditure instead of reducing food intake.

Summary

Swimming doesn’t build significant muscle mass and shouldn’t replace your regular resistance training in the gym. However, swimming is an excellent cardio exercise as it is low impact, so if you’re after an activity that won’t beat up your joints, pick swimming.

References

1. Schoenfeld, B. J. (2010). The mechanisms of muscle hypertrophy and their application to resistance training. The Journal of Strength & Conditioning Research, 24(10), 2857-2872.

2. Wackerhage, H., Schoenfeld, B. J., Hamilton, D. L., Lehti, M., & Hulmi, J. J. (2019). Stimuli and sensors that initiate skeletal muscle hypertrophy following resistance exercise. Journal of applied physiology.

3. Krzysztofik, M., Wilk, M., Wojdała, G., & Gołaś, A. (2019). Maximizing muscle hypertrophy: a systematic review of advanced resistance training techniques and methods. International journal of environmental research and public health, 16(24), 4897.

4. Schoenfeld, B. J., Grgic, J., Ogborn, D., & Krieger, J. W. (2017). Strength and hypertrophy adaptations between low-vs. high-load resistance training: a systematic review and meta-analysis. The Journal of Strength & Conditioning Research, 31(12), 3508-3523.

5. Hather, B. M., Tesch, P. A., Buchanan, P., & Dudley, G. A. (1991). Influence of eccentric actions on skeletal muscle adaptations to resistance training. Acta Physiologica Scandinavica, 143(2), 177-185.

6. Methenitis, S. (2018). A brief review on concurrent training: from laboratory to the field. Sports, 6(4), 127.

7. Baar, K. (2014). Using molecular biology to maximize concurrent training. Sports Medicine, 44(2), 117-125.