One of the often repeated comments about swimming is that it exercises your entire body. The truth of this really depends on how you approach swimming. It is possible to get in a pool and swim on your back without exerting much energy at all. However, if you are swimming laps using a stroke such as the front crawl or the breaststroke, you will use the muscles of your legs, arms, shoulders, buttocks and more.

If you are swimming at a fast pace, racing others for example, or racing against your personal best, you will experience the cardiovascular benefits of swimming. Your heart will work harder and faster to generate energy. Your lungs will also strengthen as you breathe more quickly and intensely.

When comparing different activities in regard to fitness benefits, we are really talking about how much energy is required for each one. You can imagine that this varies dramatically depending on age, sex, size, weight, body composition, fitness level, and exercise intensity. Ultimately though, we can estimate how many calories are burned during exercise by measuring the amount of oxygen consumed during it.

If you are moderately well trained and competent in the activities that you are choosing, and you are going to exercise just as intensely during each session, then it comes down to the amount of muscle mass involved and how long you perform the exercise for. Don’t look at it as 2000 meters of swimming equals one mile of running. Rather, gauge your exercise by the amount of time spent on a task.

In swimming, skill and technique significantly impact energy expenditure. Most people know how to run and ride a bike with reasonable economy, but it takes years of practice to be able to swim properly. Therefore, someone who is very inefficient in the water may be burning more calories per minute than someone who has beautiful technique. Also, experience comes into play. If you are not familiar with swimming, it may feel like you’re working extremely hard and burning a lot of calories, but in reality, you may only be working at a moderate intensity. One more difference with swimming is that if you’re monitoring your heart rate, you’ll see lower heart rates at given intensity levels, compared with running or cycling. This is due to the physiological response to exercising in a horizontal body position, and in a buoyant environment. The heart can pump more blood easier since it doesn’t have to overcome the forces of gravity to distribute it, as it does when you’re standing up.

To give you some general values, for an average-sized adult (56-68 kg woman, 63-77 kg man), in kilocalories burned per minute of exercise (kcal/min), which directly relates to the number of calories you eat each day. Realize that for larger and older individuals and higher intensities the value will be at or above the high end of the given range. Likewise, for smaller, younger, or easier exercise intensities, the value will be at or below the low end of the given range.

Burning Calories

In Swimming: At a speed of 1:20 per 100 metres (this would be very fast for someone who’s not a regular swimmer but moderate for a regular), you’re likely burning between 15 and 25 kcals per minute of actual swimming time. Therefore, one hour at this intensity would burn roughly 900-1500 kcals. These values confirm that swimming is one of the best all-around exercises available, due to the large number of muscle groups heavily involved.

In running: Running at 5:00 min per km will generally use 11-20 kcals per minute, while a speed of 3:30 per km (fast!) will use 14-25 kcals per minute. So an hour at 5:00 min per km garners a consumption of 660-1200 kcals, while an hour at 3:30 per km uses between 840 and 1500 kcals. Values are slightly lower than those for swimming since you are not using your upper body muscles to the same degree as while swimming.

In Cycling: At 16 km per hour, you could expect to use anywhere between 6 and 10 kcals per minute, while at 32 km per hour you may see a consumption of 15-20 kcals per minute. So for an hour of cycling, this ranges from 360 to 600 kcals at the lower intensity, to 900-1200 kcals at the higher intensity.

Overall, running provides the greatest potential for burning calories, although it’s much harder on your legs than swimming. A 70 kg woman running at 8 kmph burns 606 calories in an hour. Increase your speed to 12 kmph — that’s a 7 1/2-minute-mile pace, well within many runners’ capabilities — and you’ll burn 861 calories in an hour. Rollerblading burns about 548 calories in an hour, ice skating 511, cross-country skiing 496, golfing 314 — if you carry your clubs — and bicycling 292 if you average around 10 mph. But if you weigh 70 kg you can expect to burn approximately 861 calories jumping rope for an hour, 657 calories per hour on a stair treadmill, or 365 performing either resistance exercises or low-impact aerobics.

Building Endurance

One of the gold standards of measuring athletic endurance is VO2Max, which refers to the maximum volume of oxygen an athlete can utilize during exercise. Studies have shown that swimming regularly does improve athletic VO2Max and it decreases maximal heart rate while swimming. But studies have also shown that this increase in swimming endurance does not raise endurance significantly in other exercises like running and cycling. All three sports are effective at improving endurance, and running seems to be the most successful exercise for cross-training performance, but no cross-training exercise ever exceeds the benefits of specific training.

Avoiding Injury

Although swimming seems to burn fewer calories and have fewer benefits for endurance training than running and cycling, it does have a serious advantage when you consider safety. One study looked at triathletes, who perform all three exercises in tandem and at the number of injuries that occurred in each part of a triathlon. They found that 50 per cent of injuries came from running, 43 per cent from cycling and only 7 per cent from swimming. Swimming is famous for being a non-weight-bearing and low-impact way to get an aerobic workout, which means that the chance of injury remains relatively low even at competitive levels

Considering Goals

How swimming measures up against other forms of exercise depends on individual goals. For instance, because swimming is a better full-body exercise than running and cycling, swimmers have been shown to reach higher VO2Max levels during tests that involve upper-body strength. So if your aerobic goal is to improve your upper body and avoid injury, then swimming may be better. If your goal is to burn as many calories as you can and cross-train, running wins, and cycling may be a good middle ground. Doing all three, like a triathlete, can yield excellent results as well.

Swimming is an ideal form of exercise if you are dealing with injuries. For example, if you are a runner and your knees can no longer endure the impact of running, swimming will be a more manageable way to get your daily exercise.

You can also use swimming to warm up and cool down before or after running, cycling or another form of fitness activity. Swimming allows you to gradually increase your heart rate, increase your blood circulation and warm up your muscles. You can also isolate particular muscles in swimming. For example, you may want to hang on to the edge of the pool and only kick your legs. You could lie on a flutter board and move only your arms.

As a form of exercise, swimming can be very meditative. It may be very soothing and relaxing for you to swim laps at a leisurely speed or float on your back and look at the sky.

If your goal is to bulk up and build larger muscles, swimming may not be your ideal form of exercise. You will need to lift weights to increase bulk. Additionally, if your goal is to strengthen your bones, you will need to do weight training or similar weight-bearing exercise.

All in all, swimming is a great workout for your body. It works your lungs, heart and the muscles of your entire body. It is not the ideal activity if your goal is to bulk up or strengthen your bones. It is, however, a fun fitness activity that you can do alone or with others. You may also enjoy the meditative aspect of exercising in water.