Swimming: What are the benefits for runners?
On the surface, running and swimming seem about as compatible as chalk and cheese. The former is dry, vertical and performed on land. The latter is wet, horizontal and performed in the water. But this is a case of opposites attracting. As a low-impact aerobic activity, which works the hearts and lungs but spares the joints, swimming is a brilliant complement to running. Favoured by a number of elite distance runners, swimming is easily incorporated into a training schedule and carries a very low-risk of injury (assuming you’re able to float, of course). So, are you ready to take the plunge?
You’ll be following the example of some high-profile runners ditching high-mileage training plans in favour of cross training: Stephanie Kessell (née Davis), who recorded a 2:27:14 marathon to win the British Olympic Marathon Trials in 2021, and Beth Potter, who ran 14:41 at the Podium 5K in Lancashire and won bronze in the individual triathlon at the 2024 Olympic Games in Paris. Davis swims once a week on her ‘non-impact’ day and Potter swims for 90 minutes at a time, five days a week.
And then there’s Olympic triathlon champion Alex Yee, who’ll be competing at this year’s London Marathon. He told The Guardian his ambition to run 2:07-something, despite the fact he’ll be running fewer miles – 90 per week – than his competitors. ‘The top guys are doing 120-mile weeks, week in, week out,’ he said, ‘but I’m not going to be able to match that.’
But why is swimming such a good sport for runners? And what benefits will you see if you take it up?
We asked Rob Hobson, sports nutritionist at Healthspan Elite who has worked alongside British Swimming, and ice swimmer and Red Original ambassador Kate Steels to talk us through the fitness and health benefits of swimming.
What are the benefits of swimming?
Running is a high-impact activity. That’s no bad thing – in fact, it’s the reason running can contribute to better bone density – but it does mean that, on your cross training day, you might favour a low-impact activity such as swimming. Instead of pounding the asphalt, you get to float in liquid for an hour or so. What bliss.
More so than running, which is chiefly a legs-focused activity, swimming is a whole-body workout. As such, it can improve not only cardiovascular fitness, but also muscle tone and upper-body strength – something that is more important to running than many people think.
Compared to other popular cross training activities such as cycling, where you’ll ideally need to be in the saddle for a couple of hours to get comparable benefits, swimming is a fairly time-efficient way of building fitness. A solid 30 minutes of front crawl is enough to provide a good aerobic stimulus. And the fitness you gain through swimming can, in turn, help to improve your running performance – here’s how.
How can swimming make you fitter?
Boosts your VO2max
‘VO2 max is a key performance indicator that reflects an individual’s aerobic capacity and is defined as the maximum rate at which your heart, lungs and muscles effectively use oxygen while exercising,’ says Hobson.
‘Swimming is also all about breathing which is restricting when exercising, and this is what can help you to improve your VO2 max. The process of conserving air between breaths helps you to boost your lung capacity, as the lungs become more attuned to the process involved in swimming. Certain swimming drills can also be used to help improve your VO2max.’
The performance benefits of improving your oxygen intake can’t be overstated. There’s a reason VO2 max is looked at as the gold standard measurement of aerobic fitness, and why elite runners tend to register extremely high score. Moreover, a new study made another link between a high VO2 max and longevity. In short: the higher your VO2 max, the longer your are likely to live.
Improves your running economy
Running economy is the amount of oxygen that your body uses to maintain a certain pace. ‘This is an indicator of performance,’ says Hobson. ‘Poor running economy means you use more oxygen when you run, meaning you’ll be unable to maintain your pace for as long as someone with a greater running economy.’
A study in the Scandinavian Journal of Medicine and Science in Sport found that after 12 sessions of swimming with controlled breathing, the 18 subjects involved showed a 6% increase in running economy.
Balances upper-body muscle development
As runners, it’s easy to underestimate the importance of upper-body strength. Some runners even take pride in how little strength training they do. But here's the truth: if you don’t build all-round upper-body strength, your running can suffer.
‘Maintaining muscle mass in parts of the body other than the core and legs cannot be achieved from running, and fitting in weight sessions in the gym may not be that appealing to runners,’ says Hobson. ‘Incorporating swim sessions into your routine can help to train your upper body as well as your core strength.’
Builds endurance and reduces the monotony of training
The more you run, the more your heart develops the ability to meet the demands you put upon it. However, incorporating swimming into your training regime may help to take your cardiovascular endurance to another level.
‘Swimming works your heart harder than other exercises because you are engaging several different muscle groups which puts new and different stresses on the body to which it must adapt,’ explains Hobson.
It can also add some much-needed variety to your training schedule – particularly if you are not doing any form of cross training. It’s a good way of freshening things up, and giving both mind and body a break from running. As Hobson says, ‘Adding swim sessions into your routine can also break up the monotony of training.’
The health benefits of swimming
Helps to support recovery from injury
If you’re recovering from a joint or muscle injury then swimming is a good way to keep up your fitness without putting strain on the bones, joints or muscles. Swimming is a low-impact sport that helps to cushion and support without putting any pressure on joints while helping to strengthen connective tissue and build muscle around the joints while you recover.
For that reason, lots of elite runners on the recovery trail add aqua jogging to their routines. It simulates the running action, works the heart and lungs, but, crucially, reduces the impact forces quite drastically.
Gets you outdoors
Swimming doesn’t have to simply involve repeated lengths of your local 25m pool – outdoor swimming, in lakes, rivers and seas gets you out into the great British outdoors. One of the many benefits of cold water swimming is the opportunity to see and explore nature throughout the year.
‘There is nothing better than being in water, whatever the temperature,’ says Steels. ‘Sometimes it’s silky calm, sometimes rough, gurgling, bubbling or challenging; the weather is never the same and the wildlife you see in and on the water is wonderful. Each swim is unique.’
Don’t forget, if you’re swimming outdoors, never swim alone – and wearing a wetsuit will always be useful.
If wild swimming feels like a bit of a stretch, lidos provide a more controlled outdoor environment in which to swim – plus some are heated. Here’s a list of some of the best lidos in the UK.
Improves your mental health
Cold water swimming has been shown in many studies to help reduce the effects of depression. A study titled ‘Open water swimming as a treatment for major depressive disorder’ found that a weekly outdoor swim prescribed to a patient suffering from major depressive disorder could help the patient reduce, and eventually cease, medication.
‘In many areas, there are organised “Mental health swims” which encourage people to participate without any fear of stigma,’ says Steels. ‘Getting out into open water is “my space” where I can feel more at ease and I try to find my “reset” button.’
Has social benefits
‘There’s a range of informal swimming groups in most corners of the UK so it's easy to make friends with like-minded people and avoid the dangers and risks of swimming outdoors alone,’ says Steels. ‘Some groups are aimed more at social ‘dipping’ while others are focused on swimming and fitness. Safety is critical and I would recommend finding a good coach initially before plunging into open water for the first time.’
Assists sleep
Any form of cardio exercise has been shown to benefit sleep. A study by Northwestern University found that aerobic exercise can help to reduce insomnia and improve the quality of your sleep.
Try the 1K vs 5K workout
If you’re motivated by a challenge – and since you’re a runner, there’s a strong chance that you are – then here’s a fun one to try. Can you swim 1K faster than you can run 5K? Take note of your best 5K (or parkrun) PB and see if you can swim 1K in a faster time. This ratio (1:5) roughly holds across the distances, although quick swimmers can typically beat their respective run times. Give it a go!
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