How swimming can build muscle, whichever stroke you prefer

The simple answer is yes, swimming can help to both tone and build muscle.

When you swim, opposing muscle groups in your arms, legs and torso are all engaged and working together to help you move through the resistance of the water.

“Regular swimming can help build lean muscle mass,” says Heidi Portlock, a swim coach at Better Leisure who also leads the Healthwise scheme for the West Oxfordshire area.

“Swimming is a high repetition, low resistance form of exercise, so the average swimmer will see improvements in their muscle mass, strength and flexibility through regular sessions.”

Several studies have found that swimming can help to improve upper and lower body muscle strength.

One small study published in the Journal of Exercise Rehabilitation looked specifically at the effects of regular swimming on women, aged 40 to 60. The women in the study swam three times a week for 60 minutes over a three-month period, and this led to several improvements in their physical strength. These included enhanced upper and lower body muscular strength, and better muscular endurance.

However, if your main motive for building muscle is improving your swimming performance, swimming alone may not provide everything you need. A 2022 study found that a combined swimming and strength training approach will yield better results.

Maintaining muscle mass as you get older is important, and combining keeping active with strength training can be enormously beneficial. From the age of 30, we begin to lose muscle mass (a condition known as sarcopenia). Regular physical activity, including swimming, coupled with other forms of resistance exercise such as weight training, can help to protect and build muscle mass.

“If you want to focus more on building muscle, try incorporating some strength work such as resistance training – where you would be lifting weights along with swimming regularly,” advises Dr Jonathan Taylor, a senior lecturer in sport and exercise at Teesside University, and a former GB & NI middle-distance runner.

“Strength training is useful for daily life, but it’s particularly important as you get older so it’s something I would always recommend,” he says.

“Swimming is a whole body exercise that works the core as well as your arm and leg muscles,” Portlock adds. “This can help to improve balance, a key component of falls prevention. The muscle you build from swimming regularly as you get older will also help to improve your general movement and mobility.”

A number of key muscle groups are engaged and put through their paces when you swim. Let’s take a closer look at what muscles are targeted.

Your arms are constantly in use while you swim as they flex and rotate to help you move through the water; the biceps, triceps and shoulders are especially exercised with freestyle and backstroke.

Muscles in your chest and back also get a workout, though; more so when you swim breaststroke or butterfly – these include the pectoralis major (chest muscle), latissimus dorsi (back muscle) and trapezius (a muscle that spans your neck, shoulders and upper back).

Your core muscles are key in helping to keep you stable while swimming. Your abdominal muscles (including the obliques) and your lower back all benefit, and the constant need for your core to be activated can help to strengthen it.

Kicking is another essential component of the four main strokes, so key buttock and leg muscles, including your glutes, quadriceps and calf muscles, all get a great workout.

Swimming is also good news for your cardiovascular system. It raises your heart rate without putting any stress on the body. It can also help to improve your lung capacity and pulmonary health.

Each of the four main strokes – backstroke, breaststroke, butterfly and freestyle (front crawl) – works slightly differently to target key muscle areas. Here’s what each swim stroke is great for…

Tones your stomach, legs, arms, shoulders and buttocks. Also improves hip flexibility.

Strengthens your heart and lungs, and tones your thighs, upper back, triceps, chest muscles, hamstrings, quadriceps and lower legs.

It’s a hard stroke to master, but it offers excellent toning and muscle building benefits. These include improving your upper body strength, and toning your chest, stomach, arms and triceps. Butterfly also helps to increase your flexibility and suppleness as it helps to stretch out your body.

Tones your stomach, buttocks and shoulders, and is the best stroke for toning your back muscles due to the way your arms move through the water.

The short answer is they all help, but what they do varies.

“Butterfly and breaststroke are great for building muscle as they create a lot of frontal resistance,” explains Carl Cawood, a swim coach and product development manager at Total Fitness.

“Butterfly is one of the most demanding strokes – it engages the chest, shoulders, back, core and legs, but it particularly targets upper body muscles such as the deltoids, pectorals and triceps.

“While breaststroke is not as intensive as butterfly, it’s still really good for targeting the muscles in the chest, shoulders and arms, including the pectorals, deltoids and triceps. The leg movement also works the muscles of the hips and inner thighs.”

Portlock adds: “Freestyle (front crawl) and backstroke are similar in how they engage and work the shoulders, upper back, chest and arm muscles, including the triceps. These two strokes also help to strengthen your core and glutes, as well as your hip flexors and leg muscles.”

Another way you can get your muscles working harder during a swim is to incorporate additional training aids.

“Swimming is one of the best forms of exercise when it comes to providing an overall, full-body workout,” says Cawood.

“But complementing it with pool-based resistance training can further help to build muscle. Adding in swimming equipment such as pull buoys, kickboards and hand paddles can help to increase resistance so your muscles have to work harder. You can also add resistance by wearing loose-fitting swim attire as this will create more drag.”

If you want to go further with building muscle or improving your strength, Cawood suggests adding in some weight training or participating in regular fitness classes such as functional training (a type of exercise that trains the same muscles you use for everyday movement), or HIIT circuit-type sessions.