The Treadmill Vs. Running Outside: Which is Harder on the Body?

Many runners come to a point in their athletic life when they notice more aches and pains, whether from age or from overexertion. Regardless the reason, it might cause one to seek for a safer way to run that is gentler on the body. This often leads to the question of whether running outdoors is harder on the body than running on a treadmill.

Running outside is harder on the body than running on a treadmill. When running on a treadmill, athletes are better able to focus on and perfect form, control variability, and affectively avoid injury. Treadmills are also softer due to their padded tread, and are gentler on a runner’s joints and soft tissue. 

Runners fall to injury when their runs are less than perfect and their environments present obstacles (weather, uneven surfaces, difficult terrain.) If the goal is to avoid injury, then one should do their running in the environment in which they have the most amount of control, which points to: indoor running on the treadmill. However, even treadmills have their pros and cons. 

Determining Factors: How Running is Hard on the Body

Perceived Effort

One way to determine whether running indoors or outdoors is harder than the either is by evaluating something called ‘perceived effort.’ Perceived effort refers to the mental anticipation of ‘how hard’ an activity seems. 

Most individuals’ perceived effort when it comes to outdoor running is that it is harder than running on a treadmill indoors. Even if the activity itself is not actually harder, it is perceived as harder, which ironically makes the exorcise harder for the individual. This is only problematic in that athletes are more likely to give up sooner when the perceived effort is greater.

Physical Injury or Side Effects

One of the most tell-tale ways to know if one form of running is harder than another, is by evaluating the likelihood of injury and the occurrence of physical side-effects. There is no proof that outdoor runners have injured knees more so than do treadmill runners. However, what has been determined by running coaches and doctors alike, is that improper running or overexertion determine likelihood of injury. 

Running Outside

Running outside has a plethora of benefits, including many mental health benefits. Being outside in the sunshine allows one to soak up vitamin D, breathe in fresh air, and feel connected to nature and one’s community. 

However, outdoor running presents several obstacles. Afterall, it is not running itself which is inherently hard on the body. It is running incorrectly that is hard on the body. Unfortunately, it is simpler harder to control and limit the likelihood of injury outside than it is indoors on a regulated machine. 


  • Mental Health Benefits – Hopkins Medicine has conducted studies  that show running outdoors improves mood, memory and focus, ability to switch tasks, and lowers anxiety and stress.
  • Improves Stability & Lateral Agility – when running outside, you improve more of your motor skills and levels of agility, due to the different types of terrain, obstacles, and the ability to make turns.
  • It’s Free! – one of the greatest perks of running in the great outdoors (aside from the bird and people watching) is that no gym membership is required.
  • Best Way to Train for Events – Unfortunately, there is no substitute for running outdoors when training for a marathon or triathlon.
  • Builds Bone Mineral Density  – the high-impact, weight-bearing nature of running outdoors can help build bone mineral density (even more so than cycling!)


  • Hard on Soft Tissues – the University of Applied Sciences in Netherlands have found soft tissue and joint injuries (like those of knee or ankle injuries) to be more prevalent in runners who exorcise outdoors vs. on treadmills.
  • There are Uncontrollable Hazards – running outside presents other dangers and unexpected scenarios like: uneven terrain, drivers who text and drive, dogs, cyclists, weather hazards (rain, hail, extreme heat.) There have been many stories in the news about women being attacked while running at night as well. These are types of dangers that can be controlled when running on a treadmill.
  • Harder to Perfect Form – it is harder to perfect your form on road gravel, outdoors than it is on a treadmill. Due to the level of variability, and the lack of mirrors, you can’t necessarily evaluate whether you are keeping a consistent and healthy form (which could lead to injury)

Running on Treadmill

Treadmills are one of the most popular exorcise machines (in both home gyms and public gyms.) According to the U.S Consumer Product Safety Commission, it is estimated that over 50 million Americans use a treadmill each year.  Not only are they popular, but they are very effective for keeping up one’s cardiovascular health, and for teaching proper running technique.


  • Easier on Joints & Soft Tissues – since treadmills are padded, they offer better shock absorption than pavement or trails outside. This equals less stress on knees and ankles, which ultimately means less injury and necessary recovery time.
  • Can Perfect the Correct Running Form – when running on a treadmill, you are often running while facing a mirror (particularly at a public gym.) This allows you to do a visual check in and appraisal of your running posture: Is your back straight? Are you looking down when you run? Are your arms moving in excess? Are you taking too short of strides, cutting off your leg mobility? Running on a treadmill better allows for one to practice and perfect their running form, so when you do run outside, you prevent injury. 
  • Maintain Steady Heart Rate – in line with perfecting one’s form, using a treadmill allows for an athlete to concentrate on maintaining a steady heart rate, not only for cardiovascular health, but in lieu of training for longer runs or races as well.
  • Lower Perceived Effort – running indoors on a treadmill is often perceived as being less difficult than running outdoors, and as such individuals are likely to go for longer runs and push themselves a little harder.
  • More Control – overall, running on a treadmill allows you to have more control over your exorcise. You don’t have to account for spontaneous changes in weather, air pollution, distractions, unexpected or difficult terrain, or sudden inclines.
  • It’s Convenient – for some people, it is much easier to hop on a treadmill than it is for them to head outside (especially in a busy city setting.)


  • Boring – the plain fact is, running on a treadmill is terribly boring to most people. Compared to breathing in fresh air, basking in the sun, and having something to look at, a treadmill offers little in the way of entertainment. 
  • Limited Variability – running on surfaces that vary in texture, include, and stability help to strengthen different parts of your muscles and increase stability. However, a treadmill likes most variants to increase such stability and acute muscle strength.
  • Can’t Make Turns – just as variability aids your stability, a lack of turns prevents you from improving your lateral agility.
  • You Can Still Get Injured – Just because you run on a treadmill doesn’t mean you are magically exempt from injury. Afterall, we’ve all witnessed that person at the gym who either isn’t paying attention, is running too fast, or dancing and they trip, fall and then fly off the treadmill. You can still sprain your ankle, fall and even incur head injuries on a treadmill if you aren’t paying attention or are pushing too hard.

Transitioning from Treadmill Running to Outdoor Running

If you are used to only running on the treadmill, be prepared to experience some discomfort when first switching to running outdoors. It takes time for the body to adjust!

Michael Conlon of Finish Line Physical Therapy has some excellent times on how to transition from running indoors on your treadmill, to running on pavement outside. Watch here!

  1. Self-Evaluation – before you transition to outdoor running, do a self-evaluation on your current level of health and running ability. What is your maximum heart rate on the treadmill? What heart rate do you typically maintain on your treadmill?  Are there any current aches and pains that need your attention? Knowing where you are now will help you gauge how well you are transitioning to outdoor running.
  2. Appraise your Shoes – if you’ve been running on your treadmill all winter long, 5 days a week, and are now seeking to run outdoors come nicer weather, make sure you haven’t warn out your running sneakers! If you have significant wear and tear, you’ll want to invest in new running shoes before heading outside for a job.
  3. Prepare for Variabilities – when jogging indoors on your machine, you get to control the climate, the incline, speed, and feel of your run. However, when you switch outdoors you have no such luxury. Be prepared to endure things like wind speed, humidity, heat, rain, uneven surfaces, and hard ground.
  4. Foam Roll – before leaving the house for your first outdoor run, roll out on the foam roller to loosen up your calves, quads, and hip muscles.
  5. Stay Hydrated – Be sure you drink enough water not only the day of your transition from running indoors to outdoors, but make sure you drink enough water the day before. Our bodies are dehydrated before we even feel thirst. 
  6. Stretch the Whole Body – as you do at the start of any exorcise class, get movement and liquidity into your body before hitting the pavement. Warming up helps prepare your body for optimum mobility. It will improve your range of motion and help prevent injury.

The Key Take Away

If you enjoy running, but are seeking a more injury free, easy on the joints alternative to outdoor runs, the treadmill is the way to go. Running on a treadmill is softer (padded) and thus reduces the impact on your joints, while still providing adequate cardiovascular fitness, keeping you well within your desired maximum heart rate.

If you are training for an event, however, like a marathon or triathlon, you will need to train (at least partially) outside to prevent things like runner’s knee from occurring during the race. However, you can split your training time between treadmill and pavement, so that you are practicing maintaining a steady heart-rate and still getting your cardio in, but not constantly putting so much pressure on your knees and shin bones.

Relate Content

In running, the shoes you wear are everything. You could have the most endurance and stamina in the world, yet if your feet are sore from ill-fitting shoes, your performance will be negatively affected. Choosing your running shoes should not be a decision made lightly then. Instead, you want to take your time and do your research. What should you look for in the perfect running shoe?

You’ve recently decided to take up running. You love the freedom you feel when you’ve hit your stride, not to mention how fit running is making you. It’s your goal to participate in a race sooner than later, and you’ve already started preparing. A running buddy of yours suggested you buy some running socks as part of your training, but you’re not so sure. Are running socks worth it?

Geoff Southworth

I am a California native and I enjoy all the outdoors has to offer. My latest adventures have been taking the family camping, hiking and surfing.

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