When one talks about cardiovascular exercises, running and swimming immediately spring to mind. This is because both these activities are so natural to human beings that they have been a part of the evolutionary process. While our long-gone ancestors may have had to do these activities to survive, modern-day men and women have different reasons, the chief one being the need to be fit.

As with any situation equipped with similar choices, people find themselves in doubts about whether to choose swimming or running. The criteria that is often chosen to weigh these two activities is the amount of calories burned in a particular amount of time. Passion and interest apart, the ideal choice should be one where more calories are burnt with relatively lesser effort.

However, this factor is tough to account for since everyone has their own preferences when it comes to the exertion levels used in performing an exercise. The amount of calories burned will also differ depending on the physical features of a person - like the height, weight, and body composition. The fairest evaluation can be carried out if both these exercises are compared when they are performed at the same exertion level, which can range from low to high, and for the same duration of time. Let us have a look at the numbers that correspond to both the exercises at different levels of exertion -

Calories Burnt During Swimming and Running

Low Intensity
When swimming and running are carried out at a leisurely pace, with frequent pauses and slow movements, the intensity and exertion levels are low, and the result is that not many calories are burned.

Low Intensity
Activity130 lbs155 lbs190 lbs
Swimming for an hour354422518
Running for an hour472563690
Reference: Department of Health and Family Services

Moderate Intensity
Moderate intensity means that the exercises are carried out at a medium level of intensity. For running, it implies a pace slightly higher than the usual jogging pace, whereas for swimming, it relates more to continuous swimming at a decent pace, as opposed to taking frequent breaks.

Moderate Intensity
Activity130 lbs155 lbs190 lbs
Swimming for an hour472563690
Running for an hour679809992
Reference: Department of Health and Family Services

High Intensity
High intensity means the exercises are performed at a high level of exertion. For running, it will imply sprints and fast-paced running, whereas for swimming, it will imply a high number of laps without stopping; swimming continuously at a fast pace; or using tougher strokes like the butterfly stroke.

High Intensity
Activity130 lbs155 lbs190 lbs
Swimming for an hour590704863
Running for an hour88510561294
Reference: Department of Health and Family Services

As observed from the above data, when both the activities are performed for the same amount of time and with a similar degree of exertion, running has the upper hand over swimming. Given below are the reasons which tilt the calorie burning trophy towards running.

Reasons Why Running Burns More Calories

Body Weight Resistance
In case of running, resistance of body weight is one of the most crucial factors which leads to burning of more calories. Whether running on a treadmill or outdoors, the fact of the matter is that the person is carrying their body weight entirely with the strength of their legs and core muscles. This obviously requires more effort when compared to swimming, in which case the weight of body is supported mainly by the force of buoyancy. Hence while running, more effort is required to move forward, which leads to more burned calories.

Wind Vs. Water Resistance
While running, one encounters wind resistance, which fluctuates continuously. This is not the case when water resistance comes into play. Despite possessing higher density, water resistance offered by a body of water, like a swimming pool, remains constant. The overall resistance offered by wind ends up being higher.

Secondly, all swimming strokes incorporate an aqua-dynamic posture which makes swimming very efficient. The body is able to cut through the water by minimizing the surface area of the water where contact is made. For such a thing to happen in running, a person would have to find a way to run such that most of his or her body remains parallel to the ground, to achieve an aerodynamic posture. But this is not practically possible.

Hence, running ultimately faces more resistance than swimming, and therefore, more effort is required, which leads to burning of more calories.

Performance Effort
Another factor that accounts for how many calories are burned in an activity is the amount of effort required to perform the basic movements in that activity. Now, in case of swimming, there are four major strokes :
  • Freestyle stroke
  • Breaststroke
  • Backstroke
  • Butterfly stroke
Out of these four major strokes, the butterfly stroke, the toughest stroke in swimming, undoubtedly burns a higher amount of calories in a lesser amount of time. But barring professional athletes and butterfly stroke experts, a causal swimmer does not use this stroke much. The most popular strokes used by everyday swimmers are the breaststroke and freestyle stroke, which are fairly easy to do, and hence do not burn much calories, unless done very vigorously, or for a long duration. Running, on the other hand, does not have much variation. Unless one is jogging at a very slow pace, any kind of running requires effort. Hence, an everyday runner is more likely to burn more calories than an everyday swimmer.

This factor comes into play when we talk about outdoor running, and not running on a treadmill. While running outdoors, the terrain usually does not remain constant and hence, a runner has to adapt to changing slopes. Running on an inclined slope is very tough and burns a large amount of calories. On the other hand, while swimming, the terrain is constantly the same, unless one is swimming in the ocean, which is usually not the case. Hence, it does burn a relatively less amount of calories.

From the above, it can be seen that running is more effective than swimming in burning calories, when the conditions are constant for both the activities. However, this does not mean that swimming is an inferior exercise. It has its own benefits. The best thing would be to incorporate both these exercises into your schedule and find a way to optimize the results.