You get on the treadmill, set your pace and easily travel a couple of kilometers.
Then, a few days later, you go out and run the same distance. You try to maintain the same speed you did in the gym, but it destroys you.
What is happening? Is it the weather? Your mood? Or is it really harder to run outdoors?
Conditions are different outside.
There are a couple of key reasons why running outdoors can be more difficult than on a treadmill.
First, when you run outside, you push off the ground to propel yourself forward. But when you run on a treadmill, the belt moves under your feet, helping with this propulsion (even if ever so slightly). Basically, the machine does a small part of the work for you.
Secondly, there is air resistance outside. Research has suggested that running on a treadmill is slightly easier because there is no air resistance caused by wind or even a slight breeze.
Studies show that placing the treadmill at a 1% incline makes it more similar to running outdoors, by mimicking the difficulty added by air resistance.
Lastly, the undulating terrain you have to deal with outside can make running more challenging. Even a small hill can make you work harder than when you run on flat ground.
What happens when the conditions are the same?
A large amount of research has compared the demands of running outdoors with those of running on a treadmill under equivalent conditions (for example, at the same speed).
A recent systematic review combined 34 studies on this topic and found that, overall, running on a treadmill was physically easier compared to running on the ground, resulting in:
- Lower oxygen consumption: how much energy your body needs to create to maintain your running speed.
- Less lactate buildup: How hard your body works to produce energy during the run.
- Lower heart rate: How hard your heart works to pump blood and oxygen to your muscles while you run.
But while these measurements showed that running on a treadmill was physiologically easier, the same study found that people felt It was harder (although only a little).
This could be partly due to airflow. Without the natural breeze you get when you go outside, your body can overheat faster, which could make you feel a little harsher.
Of course, it could also be that some people simply find staring at a wall on a treadmill boring, making it feel harder.
So which one will make you fitter?
Based on the research above, it seems possible that running outdoors may improve your fitness more than training on a treadmill. However, there is very little research that directly answers this question.
A study in active young men found that six weeks of outdoor running led to slightly greater improvements in fitness than six weeks of treadmill running, even though all training sessions were of the same duration and intensity.
About the author
Hunter Bennett is a Professor of Exercise Science at the University of Adelaide.
This article was first published by The Conversation and is republished under a Creative Commons license. Read the original article.
Similarly, another study in athletes found that six weeks of sprint training performed outdoors led to much greater improvements in sprint speed, compared to six weeks of sprint training on a treadmill.
With this in mind, if you were to run 2 kilometers on the treadmill, it might be a little less effective at improving your fitness than running 2 kilometers outdoors. But you'll still get benefits, and the treadmill is still a great option if running outdoors isn't possible, or if without treadmill running you wouldn't run at all.
Other considerations
Running both outdoors and on a treadmill can have some unique advantages depending on your goals and needs.
There is research to suggest that exercising outdoors in nature could have psychological benefits, including reduced feelings of depression and improved mood, compared to exercising indoors.
So if you are someone who exercises for your mental health, running outdoors might be better.
In contrast, treadmills provide a consistent running environment that allows you to precisely control your pace and distance. This could improve them if you are coming back from injury and don't want to do too much too soon.
Final thoughts
When you run outdoors, your body has to work a little harder to propel you forward. This means it can provide a slightly more challenging workout.
But the treadmill is not a shortcut.
If your goal is to improve health and fitness, both work. Instead of choosing one or the other, think of them as different tools in your training kit that you can use depending on your goals.
