Running on a Treadmill vs. Outside: What are the Pros and Cons?

Our ASICS running experts are often asked whether running on a treadmill or running outside is better. The simple answer is that they're both great ways to improve your cardiovascular fitness, improve your muscle tone and relieve stress.

But while outdoor running is not necessarily better than running on a treadmill, or vice versa, there are still some important differences between them. Understanding those differences in terms of the health benefits, running technique and the effect on the body can help you make an informed decision about the best training type for you.

The key differences between running outside vs. a treadmill

1. Muscle activation

   One of the key differences between running outside vs. a treadmill is the number of muscles you activate. Running on a flat surface and in a straight line, as you do on a treadmill, does not condition or strengthen the muscles that you use when dodging people on the pavements, hopping up and down curbs, skipping around obstructions, and running on uneven surfaces.

   That can increase the risk of injury when running on a treadmill for two reasons. Firstly, because you overwork the same muscles and bones by running in the same way for long periods. Secondly, when you do go back to running outside, you may not have the muscle conditioning to make the necessary twists and turns.

2. Impact

   It's a common misconception that pounding the pavement is bad for your bones and joints. It's not. Research from the University of Missouri shows that running outside can be even more beneficial for your bones than resistance training. That's because running on firm surfaces such as concrete and tarmac creates high ground reaction forces that strengthen your bones.

   That said, if you suffer from impact-related running injuries, such as shin splints and plantar fasciitis, then treadmill running could be more advisable for you. Treadmills are designed to absorb ground reaction forces. So, while running on a treadmill will not reinforce your bones in the same way as running outside, it will reduce the impact on your joints if you are worried about injuries.

   Here are a few other common running injuries.

3. Technique

   Interestingly, a runner's form or technique does not tend to differ when running on a treadmill or outdoors. Wherever you choose to run, it takes the typical runner around 4-6 minutes to settle into their natural gait. Once you reach that point, your running technique will be almost identical indoors and out.

   The only difference is that runners on a treadmill tend to increase their stride length and reduce their cadence slightly. That's because there's no need to respond quickly to obstructions and changes in terrain when running on a treadmill, so there's nothing to interrupt your stride.

What are the pros and cons of running outside?

There are lots of benefits associated with being in the great outdoors, from people watching to mixing up your training with trail running, interval training and more.

Pros:

• It's cheap - All you need are a good pair of running shoes and some running clothing and you're good to go.
• You can train wherever you are - Whether you're on a work trip or a holiday, running is a great way to explore a new place.
• It provides race-specific training - Outdoor running conditions the muscles and joints for the varied terrain you'll encounter during a race.
• You can enjoy the great outdoors - Research suggests that being in nature, training in the elements and seeing other people has greater psychological and physiological benefits than running indoors.

Cons:

• There's a risk of injury - There's a risk of injury with any form of exercise. However, the changing terrain and the greater impact mean that injuries tend to be more common when running outdoors.
• You're reliant on the weather - Hot, wet, icy, snowy and very windy conditions can be very difficult and even dangerous to run in.
• There's an element of danger - Hazards such as trips and falls, cyclists, cars and even other pedestrians can potentially lead to accidents.

What are the pros and cons of running on a treadmill?

There are plenty of reasons why treadmills are one of the most popular pieces of cardiovascular equipment in gyms and people's homes.

Pros:

• It's reliable - Whatever the weather, you can run on a treadmill comfortably for as long as you like.
• You can control your pace - The treadmill makes it easy to track your mileage and pace. That can be beneficial if you want to pace yourself when coming back from injury or have very specific training goals.
• It's gentler on your joints - The better shock absorption of treadmills means there's less stress on the ankles and knees than running outdoors.
• It's convenient - Being able to safely run on your own at any time can make it a better fit for your lifestyle.

Cons

• They can develop muscular imbalances -The impact may be less than running outdoors but consistent use of treadmills can result in muscular imbalances that will result in injury
• There are no turns or changes in terrain - Running in a straight line on continuously flat terrain limits your muscle activation and your ability to improve your agility.
• You can't go downhill - There's no downhill feature on most treadmills. That reduces the benefits for your anterior tibialis muscles at the front of your legs.
• It can be boring - They're fine for shorter training sessions but treadmills can become monotonous on longer runs.

The bottom line

When it comes to running on a treadmill vs. outside, there is no wrong or right answer. There are benefits and drawbacks of both - it's your job to match those benefits to your fitness goals.

If you want to improve or maintain your cardiovascular fitness, then running on a treadmill is fine. However, if you're training for a race or want to see greater benefits in terms of muscle tone, then running outside is the better fit for you.