When it is raining heavily or snowing, it’s cold or dark outside, many runners decide to stay home and run on the treadmill. But everyone has long been tormented by the question of whether running on a track is similar to running in an open area, and whether one can be replaced by another. In other words, are there differences between treadmill vs running outside.
In this article, we presented the results of two systematic reviews that examined studies that tested the physiological, psychological, and biomechanical differences between running on a treadmill and in the open air.
Curved Treadmill vs Running Outside
Do you always need a 1% incline when running on a treadmill?
Outside, you are moving relative to the ground, and therefore you need to run “against the air,” resisting it. When running on a treadmill, you are in about the same place, so running a little easier. Based on this, many people believe that it is necessary to make a slope of 1% in order to compensate for this difference.
This opinion is based on a study that showed that running with a 1% incline requires as much energy as running outside at the same speed. But the results of this study were not reproduced in others, as shown in our meta-analysis of all studies published before 2019.
This opinion is based on a study that showed that running with a 1% incline requires as much energy as running outside at the same speed. But the results of this study were not reproduced in others, as shown in our meta-analysis of all studies published before 2019. In the picture below, you can see the results of a meta-analysis: here, the average difference in oxygen consumption is shown in the case of training on a treadmill with a slope of 0%, 1%, and running outside. Oxygen consumption was only slightly lower when running on a treadmill, but the difference was not statistically significant.
Someone will say that when we run outside, we cut the air in front of us, and thus spend more energy than when we run on the track. The picture below shows that oxygen consumption – an indicator on which energy consumption depends – does not increase when the running speed is below 16 km / h.
Are we running slower on a treadmill vs running outside?
It may seem to many that running on a treadmill is boring. And sometimes it seems that it is more difficult.
Such effects are confirmed by a meta-analysis. Indeed, most runners choose a lower speed on the treadmill when they are asked to run at the same speed as outside. This effect occurs due to the fact that outside, a stream of air is directed at the runner, which not only creates an “obstacle” but also cools. And also outside, the surroundings are changing, which makes running less boring.
Are we less pushing off from the surface when running on the treadmill?
The review refers to popular belief:
“When running outside, a person adapts to acceleration, and while running on the treadmill, only the track accelerates. Therefore, the runner is not so much pushing off from the surface.”
This can often be heard from friendly trainers or even some scientists, but this is not true. It doesn’t matter whether you are moving along the surface, or the surface is moving below you. Just as when running in the fresh air, you need to push off from the ground to move forward, so when running on a treadmill, you need to push off so that you are not thrown off the belt.
Is there any other running technique used on the treadmill?
Do people run on a treadmill in any other way? This is important to know. If so, then you can expect different effects of training. Or, unknowingly, pick up the wrong shoes, in which a person will be injured more often.
There is only a slight difference in biomechanics when running on a treadmill and outdoors (picture below). For example, when running on a treadmill, most people tend to bend their knee more when they touch the surface with their feet. Factors such as surface hardness and steps per minute should also be considered.
The Bottom Line Under Treadmill vs Running Outside Comparison
Although energy costs for a treadmill and running outside are similar, in terms of biomechanics, some variables can affect athletic performance and the likelihood of injury.
For example, soft-coated treadmills are preferred during rehabilitation. However, it is important to understand that differences in surface hardness also change the running technique and which muscles will be especially involved, thereby leading to their adaptations.
It was also noted that when running on the track, the lower leg bones experience less stress than when running outside, and the Achilles tendon is under a greater load. Thus, running on a treadmill can be useful for runners recovering from a fracture of the tibia, but is harmful to runners who have had an Achilles tendon injury.
- Jones, A. M., & Doust, J. H. (1996). A 1% treadmill grade most accurately reflects the energetic cost of outdoor running. Journal of Sports Sciences, 14(4), 321-327.
- Miller, J. R., Van Hooren, B., Bishop, C., Buckley, J. D., Willy, R., & Fuller, J. T. (2019). A systematic review and meta-analysis of cross-over studies comparing physiological, perceptual, and performance measures between treadmill and overground running. Sports Medicine, 49(5), 763–782. doi:10.1007/s40279-019-01087-9
- Van Hooren, B., Fuller, J. T., Buckley, J. D., Miller, J. R., Sewell, K., Rao, G., . . . Willy, R. (2020). Is motorized treadmill running biomechanically comparable to overground running? A systematic review and meta-analysis of cross-over studies. Sports medicine, 50 (4), 785-813. doi: 10.1007/s40279-019-01237-z
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