One is vertical, high-impact and performed on land; the other is horizontal, low-impact and performed in the water. On the face of it, running and swimming share about as much in common as chalk with cheese.
What unites them, however, is that they’re both excellent forms of aerobic exercise. Many runners may already use swimming as a form of cross-training, but if you’re looking for a direct comparison of running vs swimming, here’s what you need to know.
VO2 max
Perhaps the gold standard of cardiovascular fitness, VO2 max refers to the amount of oxygen your body can effectively use while exercising. The higher the number, the better your VO2 max. Again, both running and swimming can increase your VO2 max, as indeed will any activity that gets your heart pumping vigorously. But it’s telling that elite runners tend to have higher VO2 max readings than elite swimmers. That’s due, in part, to the fast-paced, high-impact nature of running, and the large skill component involved with elite level swimming (ie, being a great swimmer isn’t all about having an elite-level heart and lungs).
What everyone's reading
Calorie burn
The number of calories you burn doing a physical activity is governed by the duration and intensity with which you perform it. So swimming the English Channel, say, will burn more calories than a 30-minute easy run. However, in like-for-like conditions, running trumps swimming here.
A 70kg person running 60 minutes at 10min/mile pace burns roughly 700 calories, according to the American Council on Exercise’s calorie counter. The same person swimming casually for the same amount of time burns roughly 500. For reference, if the runner was moving at 7:30min/miling for that period, they burn closer to 950 calories; vigorous swimming for the same amount of time burns closer to 700.
So running edges it, partly due to the fact it’s weight-bearing, but both activities score highly in the calorie-burn stakes.
Bone density
Pounding the pavements or trails has some built-in risks from an injury perspective (more on this below). The plus side is that, when supported by good nutrition and adequate recovery, this impact builds stronger bones. Swimming, which, as one observer noted, is ‘the closest a human being gets to flying’, is an excellent complement to running precisely because of its low-impact nature. But when it comes to building bone density, it flounders.
This difference was underlined in a study by the European Congress of Endocrinology. It found that exercise that puts greater strain on your skelly, such as the ol’ left-right-left, improved long-term bone health more than non-weight-bearing activities, such as swimming or cycling.
Speaking about the findings, lead author Dr Giovanni Lombardi said: ‘The everyday man and woman need to exercise moderately to maintain health. However, our findings suggest that those at risk of weaker bones might want to take up running rather than swimming or cycling.’
Injury risk
While lots of the narrative around running and injury – “It’s bad for your knees”, “It’ll ruin your hips” – has been thoroughly debunked, there’s no denying our favourite hobby comes with some risks. High-impact activities have their benefits – calorie burn, VO2 max, bone density – but they also have their drawbacks. And in the case of running, that’s often impact-related injuries. Swimming has its common injuries too – swimmer’s shoulder being the sports answer to runner’s knee – but it’s hard for even a die-hard runner to argue with the fact that swimming is less injurious than running.
What we will say, however, is that in both sports many injuries can be avoided by strength training, adequate recovery, responsible fuelling and a sensible training philosophy.
Muscle building
It will comes as no surprise to runners to learn that their chosen activity is unlikely to gain them a VIP pass to Muscle Beach. For all our sport’s endurance-boosting creds, it is not a fast-track to bulging thighs or biceps. It does have some toning and sculpting potential, due to its fat-loss effects, while running uphill can help to build more powerful leg muscles. That said, swimming is the winner here. When swimming, all the major muscle groups are engaged as you move through the resistance of the water.
When it comes to muscle building, though, weight training trumps both. Runners should ideally be lifting heavy weights twice a week – something that really will build muscle – and swimmers the same. As lauded as the ‘swimmer’s physique’ is, it’s worth noting that this has rarely been sculpted purely in the water.
1K vs 5K challenge
Finally, a fun challenge to try. Most people’s 1K swimming time will broadly correspond to their 5K running time (assuming they’re not a total beginner to either activity). Give it a go and see which one you complete quicker. That way, you’ll be getting the benefits of both activities. However, if you have to choose one, in our completely unbiased opinion, running is the better option.
