Laps and lats: Does swimming actually build muscle?

Let’s address the chlorine-scented elephant in the room: Can swimming really help with building muscle, or is it just cardio in disguise?

While the swimmer’s body is often envied for its broad shoulders and sculpted back, there’s still a fair bit of confusion about whether swimming builds muscle mass or simply burns calories while you pretend you’re Michael Phelps on a Sunday morning.

The truth? Swimming is one of the most underrated full-body workouts out there. It hits major muscles, supports muscle tone, and yes, can help you build lean muscle mass and lose weight at the same time.

It may not replace weight lifting if your only goal is size, but if you’re after muscle gain, muscular endurance, and a stronger, more functional physique, regular swimming deserves a front-row spot in your workout routine.

What are the health benefits of swimming?

Swimming workouts deliver far more than just a post-pool glow. From cardiovascular conditioning to muscle strength, this low-impact form of exercise pulls double duty on mental health and physical resilience [1].

It builds muscular endurance and functional strength

When done right, swimming offers resistance in every rep, pushing your body's muscles to contract against water instead of weights. That resistance builds muscular endurance across specific muscle groups, particularly in the upper body, core muscles, and lower limbs.

Every stroke challenges your back muscles, chest muscles, gluteal muscles, and hip flexors, while your foot muscles and leg movements keep you streamlined and powerful through the water [1]. Over time, this improves strength that translates into everyday movement, not just gym PRs.

It improves cardiovascular health without punishing your joints

Swimming isn’t just a great workout; it’s gentle on the joints, making it ideal for anyone with injuries or inflammation.

It improves heart and lung function, increasing oxygen capacity and supporting your cardiovascular system without the impact stress of other forms of training [2]. Think of it as strength and conditioning that feels like recovery (until the 10th lap).

It supports mental health and consistency

Swimming regularly has been shown to reduce stress, improve mood, and promote better sleep. The meditative rhythm of strokes, breathing, and turns helps to calm the nervous system, something your inbox, group chat, and over-complicated swim coach app can’t always promise [3].

Plus, the feel-good endorphin hit means you’re more likely to keep showing up, which (as we know at Compound) is the secret sauce to real results.

Does swimming change your body shape?

Yes — and not just by helping reduce your body weight. Swimming targets different muscle groups simultaneously, especially in the upper body and core, which over time can broaden the shoulders, tighten the waist, and enhance muscle tone.

The latissimus dorsi, upper back, and chest muscles in particular get plenty of work, especially with strokes like front crawl or butterfly [4]. Add in training fins, pull buoys, or swim paddles, and you’ve got tools to increase resistance and promote even more muscle growth.

But the best part? These changes are functional. You’re not just sculpting for aesthetics, you’re building a strong, capable body that moves efficiently in and out of the water. Over time, you’ll likely notice improved lower body muscular strength, better posture, and a leaner overall silhouette. Not quite superhero-level transformation, but not far off either.

Does swimming build muscle?

Short answer: yes. But let’s unpack it a little. Swimming builds muscle by forcing your body’s muscles to work against the resistance of water, roughly 800 times denser than air. That turns every stroke into a form of low-impact resistance training, especially when performed with intensity and good technique.

Over time, this helps increase muscular endurance, improve muscle tone, and support the development of lean muscle mass across both the upper and lower body [1].

Unlike traditional weight training, swimming activates multiple muscle groups at once, combining strength, cardio, and mobility into one highly functional full-body workout.

While you might not see the same hypertrophy as from heavy lifting, swimming regularly (particularly when paired with tools like pull buoys, training fins, or paddles) contributes to building muscle mass [4]. Think muscle gain with a side of core strength, hip mobility, and shoulder stability.

What is the best swimming stroke for building muscle?

When it comes to building muscle, not all swimming strokes are created equal. Butterfly is arguably the most demanding, targeting the chest, shoulders, core, and upper back with serious intensity — but it’s also the hardest to master.

If you’re looking for the best bang-for-your-buck, front crawl (a.k.a. freestyle) is the gold standard. It heavily engages the latissimus dorsi, deltoids, triceps, and core muscles, while your leg muscles and gluteal muscles power the kick [5]. Add swim paddles or a pull buoy to increase resistance and shift more load to the upper body muscles, turning each session into a stealth muscle-building workout.

Want to double down? Use a leg float to isolate and develop upper body strength while keeping the lower body out of the equation.

Which muscles does swimming target?

Swimming workouts engage an impressive lineup of muscle groups from head to toe. Different strokes target different areas, but the cumulative effect is a whole-body workout that builds strength, endurance, and coordination, without wrecking your joints.

Here’s a breakdown of the specific muscle groups swimming hits:

• Latissimus dorsi: The wide muscles down your back that power pulls and generate speed through water
• Deltoids and trapezius: For strong, controlled shoulder movement and stability, especially during the recovery phase
• Pectorals (chest muscles): Engage during strokes like breaststroke and butterfly, aiding in propulsion
• Core muscles: Including the obliques, rectus abdominis, and deeper stabilisers; keep your body aligned, efficient, and streamlined
• Gluteal muscles: Fire up during flutter kicks and push-offs, contributing to both muscle strength and hip mobility
• Quadriceps and hamstrings: Support leg movements and propulsion during kicking
• Calves and foot muscles: Provide ankle stability and whip-like movement during kicks, especially in freestyle and backstroke
• Forearms and grip muscles: Work hard during pull phases, especially with resistance tools like paddles

Does swimming burn fat?

Absolutely. Swimming isn’t just for building muscle. It’s also an excellent tool for burning fat. Thanks to the full-body nature of the movement, swimming workouts torch calories while simultaneously increasing muscle mass and preserving lean body mass [1].

And unlike treadmill running slogs or bike sessions that isolate the lower body, swimming gets your upper body, core, and leg muscles firing together in one streamlined (pun intended) session.

As your muscle groups work harder, your body taps into fat stores for fuel (especially when you’re training at moderate to high intensity). Over time, regular swimming paired with a balanced diet can support fat loss, reduce body weight, and reshape your physique in ways traditional cardio often can’t [3].

How often should you swim to build muscle?

If your goal is muscle gain, aim to swim at least 3 times per week, ideally incorporating a mix of strokes and intensity levels. Variety matters. Like any form of resistance training, building muscle mass through swimming requires progressive overload, pushing your muscle groups to adapt, recover, and grow stronger.

That said, recovery matters too. Swimming can feel deceptively gentle, but it still taxes your muscular endurance, core strength, and cardiovascular system.

Balance your swim days with rest or active recovery, and consider layering in some strength training or functional training outside the pool if you want to accelerate progress or target gaps in your routine.

Is swimming better than the gym?

It depends on your goals. Swimming offers a full-body workout that builds muscle strength, improves cardiovascular health, and supports fat loss, all while being easier on the joints than weight training.

But if your aim is maximum hypertrophy (read: bigger muscles), you’ll likely want to complement your swim routine with gym-based strength training exercises. The sweet spot? Combining both.

At Compound, we believe performance health isn’t one-size-fits-all. Whether your current body composition goals involve reducing body fat, gaining lean muscle mass, or just not feeling winded climbing the stairs, we’re here to make the science simple and the process seamless.

Compound combines medical treatments, diagnostics, prescriber support, and personalised nutrition and exercise plans for an effective programme that helps men unlock body recomposition. 

• Up to 15% weight loss with clinically backed treatments
• Lose fat and gain muscle with customised diet and movement plans
• Track metrics and progress within the Compound app

We’re in the middle of building something special for UK men.