Race Training: Pros and Cons of Indoor vs. Outdoor Runs (+ What Burns More Calories?)

corsa indoor o outdoor

by Olivia Raffelsberger, Sports Scientist

What’s better: running indoors on a treadmill or racking up the kilometers outside in the fresh air? Is the treadmill easier on my joints or is it more effective if I train for my race outside? 

Either way, running is the ideal cardio training. Whether inside or out — you stimulate your muscles, get your heart rate up, and burn calories. However, it’s always a good idea to understand the pros and cons of running indoors and outdoors.

Advantages of Running Indoors

It’s too dark! Too rainy! Too cold! In the cold season it usually takes a lot of motivation to get yourself moving. But before you stick your running shoes in the corner to gather dust, you might want to consider the indoor option. In the gym or the comfort of your own home — just push a few buttons on the treadmill and start your own training routine to get you through the winter: 

  1. You will get precisely the training you need on a treadmill: incline, pace, and interval. 
  2. Hot, sunny days or cold and rainy — when you run indoors the weather doesn’t matter. In the summertime you benefit from the air conditioned rooms in the gym, and when the temperature nosedives outside, you’ll appreciate the central heating. 
  3. An integrated cushioned belt reduces the impact on your joints. The way you run on a treadmill is also easier on your body. Midfoot strike, lower knee lift, and a slightly faster stride frequency reduces the impact on your joints. 
  4. There are no red lights. You can focus entirely on running and nothing slows you down. The treadmill helps you maintain your own pace, and the risk of injury (due to poor visibility, ice) is also lower.  
  5. Are you preparing for a longer race? Then you should think about fueling up during the race. On a treadmill you can practice snacking while you run without slowing down.

Disadvantages of Running Indoors

No, you aren’t imagining it — running indoors feels different than a long run outdoors. It’s not surprising; the moving belt does some of the work for your legs. This is why your running technique looks a bit different on a treadmill. When you run on a belt, you are less likely to actively stretch your hips, and you don’t land as heavily on your back foot as when you are running outside with a headwind. This also affects the length of your stride (shortens it). The neuromuscular system doesn’t have to work as hard on the treadmill and the stabilizer muscles are less active. This is especially true for the calf muscles, which don’t get worked as hard indoors. But remember, ankle stability is very important for every outdoor runner and prevents injuries. 

Advantages of Running Outdoors

Hardcore, all weather runners lace up their sneakers and head outside, rain or shine, because as the saying goes, “there is no such thing as bad weather, just bad gear.” If you can brave the elements, you’ll save the cost of gym membership (or a home treadmill) and also enjoy plenty of other benefits:  

  1. After a long day in the office, fresh air will energize you. Unwind and enjoy the peace and quiet, or meet up with friends for some social time in your sneakers. 
  2. Refill your vitamin D stores. Your body and your immune system really need this, especially when the temperatures drop.
  3. Running on different surfaces (road, trails, etc.) always presents new challenges for your body. Improving your coordination and working more muscles prevents injuries. 

Disadvantages of Running Outdoors

The cons of running outdoors are obvious: bad weather, darkness, and risk of injury. Another one that not everyone may be aware of is personal safety. Depending on where you run, you could be putting yourself at risk. Make sure to stay safe by running well-lit routes if it’s dark outside, and run with a buddy to keep you company. Many choose to run without headphones so they can hear what’s going on around them. 

Did you know…

…in the adidas Running app you can track a run LIVE? This way, your friends can see where you’re running, cheer you on, and will notice if something looks unusual. 

Does Running Outside Burn More Calories?

As far as your metabolism is concerned, it doesn’t matter whether you’re inside or out. On a treadmill or the trails, running is a great way to get fit.

Back in 1996…

…a study by Jones & Doust showed that a 1% incline on a treadmill simulates running outdoors.(1) If you slightly increase the treadmill incline and run at the same pace, you will burn basically the same number of calories — whether you’re indoors or out.

The reason for this is a simple one: when you run on the treadmill, it supports your running and the headwind or wind resistance disappears. When you run outdoors, the wind resistance increases the faster you run. 

Make Your Indoor Running More Effective

Many people consider the treadmill a good alternative that adds variety to your daily workouts. With just a few tricks you can make up for the drawbacks of indoor running:

  • The best way to simulate outdoor running is to set the treadmill incline at 1 or 2 degrees. You’ll achieve about the same intensity as outside.   
  • Short, fast intervals add variety to a treadmill workout. You can play with the incline and simulate short hills perfectly. 
  • Runners tend to have a shorter stride on a treadmill. Looking down at a small screen also makes you hunch your back and tense your shoulders. If you find something at eye-level to focus on, it will help you straighten your back and lengthen your stride.
  • Modern treadmills are built to absorb the shock of impact. So, consider this when you buy your running shoes. 
  • Keep your training interesting with new podcasts, audiobooks, or a training partner.

If you want to know how hard you’ve pushed yourself, check your heart rate and monitor changes. 

man running outdoors

So, what now…?

If you are familiar with the differences between running on a treadmill and running in the fresh air, you can be flexible about adapting your race training to the gym or outdoors. If it’s cold (-10 degrees), dark, and the ground is icy, opt for the treadmill. Remember: start at a slower pace and speed it up in increments. This will help you get a feel for running on a moving surface. 


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