Walking Outside vs. Walking on a Treadmill: Which Is Best for Your Health?

Reviewed by Michele Stanten, ACE-GFI

Working out isn't just about long-distance races and trendy boutique classes. Walking can be an affordable, accessible way to stay fit and has been shown to promote weight loss, improve flexibility, and boost your mood.

Walking also provides a lot of autonomy—from choosing the time you start and stop to picking the music or podcasts you play. You also have the option of lacing up for the treadmill or hitting the great outdoors, and each setting comes with its own pros and cons.

Benefits of Walking Outside

Beyond the fact that it's free—after you've bought the right walking shoes of course—there are other added bonuses to heading outdoors. If you're headed outside, you can:

Burn More Calories

Walking outside comes with certain obstacles that make your body work harder, like wind resistance and pushing your own body to move forward, unlike a motorized treadmill that will keep you going with less effort on your part. When your body has to expend more energy, you burn more calories.

Related: Running on a Treadmill vs. Outside

Strengthen Different Muscles

The sloping sidewalks, steps, and other variations of outdoor terrain help strengthen stabilizing muscles that facilitate balance and core strength, both of which are vital to your overall health as you age. And if you live in a hilly area, you can work glute and quadricep muscles when trekking uphill and lengthen and condition muscles when walking downhill.

Boost Your Mood

Multiple studies confirm the benefits of "green exercise," the connection between outdoor physical activity and improved mental health. A 2014 study comparing physical and emotional health after outdoor vs. indoor activity found that exercising in nature was directly related to better emotional well-being.

Studies from 2013 and 2015 concluded that walking in nature was associated with less stress, less anxiety, and better working memory than walking in an urban area. The time away from your screens and stresses gives your mind and body a chance to take a break, breathe in fresh air, and connect with people in your community.

Related: How to Make Your Own Walking Stick

Train For Longer Distances

The treadmill is handy for within-week workouts of 30 to 60 minutes and to work on your walking posture and form, but for your long, slow distance mileage, head outdoors. On a longer distance event, your muscles will begin to tire and you'll need to "recruit" different muscles to push forward and reduce the chance of aches and pains.

Outdoor training is more likely to use more muscles for balance, stability, and ups and downs than the smooth ride of the treadmill.

Related: 5 Outdoor Walking Workouts

Boosts Vitamin D Levels

The sun is the best source of vitamin D—so walking outside is a great way to boost your levels of this important vitamin. This vitamin is important in keeping bones strong and healthy, as well as affects other aspects of your health like mood. A vitamin D deficiency is caused by not exposing your skin to the sun, often due to factors like geographic location or the season. Those with darker skin pigments are also at more risk of vitamin D deficiency as this skin type takes longer to absorb the recommended amount.

Experts say there is a safe way to expose your skin to the sun without causing sun damage or increasing your risk of skin cancer. In spring and the summer, you can wear shorts and a tank top and walk outside for 8 to 10 minutes at noon. That is all you need to get the recommended amount of vitamin D. If you are walking outside longer, carry sunblock and apply it after the recommended time is up.

Improves Motivation to Exercise

Walking outside may just be the added boost you need to stay motivated to exercise. One study looked at people with obesity and they reported walking outside was much more enjoyable than exercising inside. You may be more likely to stick to the exercise routine if you look forward to it, as well as exercise for longer periods of time. They also reported an improved mood and less stress after exercising outside, which is another incentive to prevent you from blowing off your exercise session.

Disadvantages of Walking Outside

While leafy trees and beautiful vistas may make for a more visually pleasant workout, going outdoors isn't always the most practical choice. Walking outside comes with challenges like:

• Harder surfaces: If you have joint issues, pavement can put undue stress on knees, ankles, and other joints. If you have the option, avoid concrete and choose asphalt or better yet, dirt or pea gravel.

• Safety concerns: Maybe your neighborhood doesn't have sidewalks or there are other obstacles like dogs occupying your path. No matter the reason, if you don't feel comfortable walking outside, it's best to stay indoors.

• Weather issues: While some people embrace less-than-ideal conditions, rain, snow, or high winds can make for a dangerous excursion or even just give you an excuse to forgo your workout for the day.

Benefits of Treadmill Walking

Using a treadmill for your regular workouts is a great way to train your walking muscles, practice your form, and achieve greater walking speed. If you opt for a treadmill, you can:

Not Dependent on Weather

It is hard to get motivated to exercise outside if it is cold, too hot, or rainy. A treadmill can be used rain or shine and at any time of the day or night. Having the option of a treadmill, such as a nearby gym, is a good alternative to keep exercising even when the weather outside isn’t optimal. 

Better Control the Workout

Beyond keeping your climate stable—and fewer reasons to skip your workout—walking on a treadmill comes with the benefit of pre-programmed workouts, such as interval training or simulated hills. The treadmill may also have a digital screen that displays vitals like heart rate, calories burned, and average speed—feedback that can help improve your next walk.

If you live in a flat area, you can easily increase the incline to give yourself a more challenging workout.

Walk Faster

Most people set their treadmill workout for time rather than for distance and can often go faster on a treadmill due to lack of obstacles. For example, having to stop at streetcorners and even wind resistance can slow down an outdoor walk. More speed equals more distance for the same amount of time, which in turn equals more calories burned than if they walked outside for set distance rather than for time.

Stay Entertained

Listening to music or podcasts outdoors can sometimes be dangerous, but in an indoor setting, you're relatively free to listen to anything, watch TV, or read a book. For those who get bored on a walk, having a distraction can help the time fly.

Related: Playlist of Songs About Walking

Helpful for Those With Injuries or Mobility Issues

Because you can more precisely control the speed and incline on a treadmill, this may be a better form of exercise if you are recovering from an injury or have other mobility issues. For example, if you are recovering from a knee injury, you can make sure you keep the incline flat and you don’t need to worry about walking up curbs or stumbling on gravel. As your strength improves, you can add a faster speed, time and increase the incline level. Treadmill walking is a great way to monitor your progress, as you can keep track of factors like incline level and speed. If you have other mobility or endurance issues, you can stop the treadmill and rest if you feel fatigued, versus being stuck someplace if exercising outside.

Related: Best Cardio Workouts and Exercises for Bad Knees

Disadvantages of Treadmills

Posture, price, and cost are important factors to consider if you want to start a treadmill walking regimen. If you choose this route, it likely means you'll:

• Burn fewer calories: Without hurdles like wind resistance or varied terrain, your body doesn't have to expend as much energy and in turn, doesn't expend as many calories. One solution is to up the treadmill incline—runners typically increase by 1 to 2%—to more closely mimic the outdoors. Keep in mind that holding onto the handrails will further reduce the calories you burn and affect your walking posture.

• Have fewer downhill options: While most treadmills offer an incline option—great for building glute and quadricep muscles—it's less common to find a treadmill setting that simulates a downhill motion, which strengthens the anterior tibialis muscles and soleus muscles, in the front and back of the lower leg. If you're training for a long-distance race, using only a select group of muscles may not adequately prepare you for a hilly course.

• Spend more: Whether you're buying a treadmill for your home or paying for a membership at a gym with treadmills, that treadmill walk will end up costing more than heading outside or walking outside.

Related: 10 Walking Mistakes to Avoid

The Bottom Line

As with any wellness practice, the best option is the one that will keep you consistent. Opt for the setting that will motivate you to move on a regular basis. That may mean initially starting at a slow pace—particularly if you're on a treadmill and not used to walking without using the handrails—but you'll ultimately get a better workout.

And if you prefer walking indoors or are contending with bad weather, remember there are other ways to walk indoors, including walking through malls, on indoors tracks, and marching in place.

Related: 10 Ways to Walk Your Way to Fitness and Health

Frequently Asked Questions

Is walking outside or on a treadmill better for weight loss?

Research has found that you actually burn more calories walking outside than on a treadmill, as you must walk over uneven surfaces, up and down hills, as well as deal with factors like the wind. All of this makes your muscles work harder, which means you burn more calories. This is a generalized statement, however, as you can also adjust the treadmill to have an incline and increase the speed so you burn more calories as well. You can lose weight with both methods of exercise. The best way to lose weight is to exercise consistently and watch your diet–so whichever exercise you will do on a regular basis will show the most results in the long run.

Can walking on a treadmill provide the same cardiovascular benefits as walking outside?

The treadmill is a great way to get in the recommended 150 minutes of moderate-intensity exercise per week. Experts say that interval training, in which you alternate between a short bout of high-intensity exercise with a longer bout of lower-intensity exercise, is the best way to improve your cardiovascular health. You can do this outside or inside on treadmill. Warm up with a five-minute walk on the treadmill, followed by five minutes of fast walking or jogging. You can also add an incline. Slow down to a moderate pace for one to three minutes. Continue repeating this sequence for at least 30 minutes.

Does walking outside or on a treadmill have a greater impact on joint health?

A treadmill is softer and has more shock absorbency than the ground outside, which means less impact on your joints. In addition, a 2014 study found that runners had a shorter stride length on the treadmill, which means less impact on your hips, knees, and ankles. On the flip side, however, the higher impact of running outside stimulates bone growth and preserves muscle mass better than running on the softer treadmill. If you have joint pain from running outside, it is best to stick to the treadmill. If you don’t have pain, running outside will keep your bones strong and healthy. To get the best of both worlds, you can add both outside running and treadmill running into your routine.