Whether you are training for fitness or to returning to running after injury, one question naturally occurs: Can I use a treadmill, or should I focus on running outdoors? Today we build on the previous article regarding running form, and look at the pros and cons of both to answer that question.

In the end, there is no one size fits all approach to the debate around treadmill vs. outdoor running. Both approaches have advantages and disadvantages, dependent on your personal training needs and goals.

Person using a treadmill

Running Indoors

Running indoors often requires access to a treadmill, unless you happen to be a professional athlete with the luxury of an indoor athletic track. We know from our previous article that running biomechanics look subtly different when using a treadmill versus running on pavement or trail.


Running indoors gives you complete control over the environment and workout. You can choose when to increase the pace or gradient, instead of reacting to the outdoors. This allows you to monitor all of your metrics at all times, making it easier and more motivating to see your progression week by week, and to plan specific workout goals.

Using a treadmill means you never have to worry about unfavourable weather conditions or fading light cutting your workout short. You can don or doff your layers as you please, and you won’t ever have to carry a heavy bottle of water or cake yourself in sunscreen.

If you are fortunate enough to own a personal treadmill at home (see our best treadmill review for recommendations and price comparisons), you can even burn that midnight oil without worrying about gym opening hours.

If you are the type of person that finds running extremely boring and just cannot seem to motivate yourself then using a treadmill is a great way to multi-task. You can watch television, listen to a podcast, or play your music all in the confidence that you will not be blocking out the unexpected hazards that come with outdoor running. Just plug in and run.

When it comes to injury prevention and rehabilitation, treadmill surfaces are usually more forgiving on your knees and hips than running outdoors. This is thanks to the thick rubber belt providing some additional shock absorption, thus reducing ground reaction forces (GRF), which transmit up through your long bones and in to the joints.

The subtle changes in the way you plant your foot also further reduce GRF (as discussed previously) and in turn spare the joints comparative to the paved surfaces we often run on outdoors. Not only has this but the control over gradient and speed meant you can alter the environment in order to avoid up and down hill running, which of course changes load.


Indoor running on a treadmill is such a controlled environment that it does not offer the same challenges to your proprioceptive and feedback mechanisms that outdoor running does.

Proprioception, defined as the perception of joint positioning and awareness of bodily movements, is a fundamental factor for maintaining joint stability and balance. Taking proprioception stimulation out of your workout entirely is not always a good thing.

When running on a treadmill you are also limited in terms of direction, as you cannot make any turns, which would normally be useful for challenging your agility.

A lack of terrain change, most notably in that you cannot run downhill, means that you do not have the ability to work your hamstrings, Tibialis anterior and gastrocnemius as much as you would do outdoors. In turn, this could potentially contribute to certain muscle imbalances if not balanced out over time.[1]

Finally yet importantly, some of us just find treadmill running to be downright boring, especially the long distance runners among us. If you crave the great outdoors and a variety of environments to keep you mentally tuned in to the run, then a treadmill is not for you.

After injury

The controlled environment of the treadmill can be extremely useful for return to sport and conditioning after surgery.

I frequently use the treadmill in practice after hip, knee, and ankle surgeries in order to rebuild strength-endurance and cardiovascular fitness.

We also have fantastic innovations now, such as the Alter G treadmill, which allow us to reduce bodyweight up to 80% whilst running. This can be very useful for unloading tendons and joints that cannot tolerate the normal stresses associated with running.

With many orthopedic surgeries, timing is crucial when re-introducing running. For this reason, it is crucial that you see a physiotherapist who has good relations with the surgeon and/ or an understanding of the surgeon’s post-operative protocol.

Typically, you can expect to start treadmill running once comfortable after arthroscopic debridement without repair, 3 months with repair, and 2-3 months after ACL reconstruction. After knee replacements’ this can also take 2-3 months, although it is dependent on a multitude of factors.

Again, this is why it is crucial that you see an appropriately qualified and experienced Physiotherapist to guide you after surgery.

Running Outdoors

Outdoor running is a fantastic way of improving your general health, especially in areas with good air quality like coastal paths, country parks, and countryside villages. The fresh air not only benefits your heart and lungs but your mental wellbeing also.


Running outdoors, as a weight-bearing activity, has added benefits for building and maintaining bone density, helping to stave off osteoporotic changes later in life.

An English study published in 2017 even demonstrated clinically significant changes in bone density in females who performed 60-120 seconds of high intensity weight-bearing activity, versus those who did nothing at all.[2]

When preparing for an event, running outdoors also conditions your muscles and joints better, versus a treadmill, to the varied terrain you will encounter in a race.

As one of the most inexpensive and accessible sports on the planet, running outdoors gives you less constrictions on equipment and facilities required. No gym membership, no treadmill, just trainers and will power required.

You can even incorporate running in to your daily travel schedule. Try swapping it for those last ten minutes in the car on the way to work. This way, running becomes part of your normal routine and less of a chore.


Running outdoors is often at the mercy of favourable weather conditions. If you are running with specific fitness goals or with the intention of beating a personal best then perhaps a treadmill is worth considering.

Running in wind, snow and rain does have the potential to cause injuries, and can require multiple layers of often quite expensive clothing.

Predictability of environment and a quality-running surface cannot always be controlled or guaranteed. This again presents a risk of injury, particularly for those who lack agility, proprioception, and the ability to react promptly to unpredictable hazards.

For this reason, I prefer to encourage my patient’s in clinic to start with the controlled environment of the treadmill, where they can build confidence, speed, reaction time and proprioceptive control. Then we can progress on to outdoor running more comfortably.

After injury

The key to returning to outdoor running after injury is in being aware of how your body reacts and responds.

There should be full range of motion and little to no joint swelling both before and after you finish. Additionally, no increased laxity is important as this indicates a potential loss of joint stability.

In regards to pain, sometimes it can be very normal to have minor discomfort during and after exercise, however this should go away within 15-20 minutes of finishing that activity.

Final Thoughts…

More often than not, for those who are fit and well, a combination of both indoor and outdoor running is the perfect balance. This keeps us well tuned in to the specific hazards that both have to offer, whilst allowing us to enjoy the benefits of both.

For those who are rehabilitating or looking to make a return to running but not sure how, I would recommend reading my previous article on running form and treadmills. You should also consider reaching out to an experienced Physiotherapist or health and fitness professional in your local area for individualised expert advice and guidance.

[1] Cai, Zong-Yan et al. ‘Comparison of Lower Limb Muscle Activation During Downhill, Level and Uphill Running’. 1 Jan. 2010 : 163 – 168.

[2] University of Exeter. (2017, July 18). One minute of running per day associated with better bone health in women. ScienceDaily. Retrieved November 19, 2021 from www.sciencedaily.com/releases/2017/07/170718084535.htm

Latest posts by Jack Rosser - PT, BSc, MCSP, HCPC, FMPA. (see all)