However, it is best to mix it up.

A study from 2019 titled Is Motorised Treadmill Running Biomechanically Comparable to Overground Running? A Systematic Review and Meta-Analysis of Cross-Over Studies suggests that running only on a treadmill may affect your gait.

“Spatiotemporal, kinematic, kinetic, muscle activity and muscle-tendon outcome measures are largely comparable between motorised treadmill and overground running,” the study said.

“Considerations should, however, particularly be given to sagittal plane kinematic differences at foot strike when extrapolating treadmill running biomechanics to overground running.”

Or in normal speak: running is basically the same on a treadmill and outside, but the way your foot lands might be a bit different.

The study found that load increased in some places, and not others, compared with outdoor running, so the risk of injury did not change – it just changed where the injury could occur.

For example: “Although bone compression and strains, measured via an implanted bone strain gauge, and plantar fascia strains have been found to be lower in [treadmill] running, peak forces and loading rates on the Achilles tendon have been shown to be higher during [treadmill] running.

“[Treadmill] running may therefore be suitable for rehabilitation from lower limb stress fractures, but not Achilles tendinopathy, Achilles ruptures or calf muscle strains.”

Pros of a treadmill

• Build your fitness precisely – a common issue is doing too much too soon and getting injured. Running on a treadmill will allow you to precisely increase your speed and mileage.

• Convenience – if you are close to a gym but not somewhere suitable to run, it can be a time saver for runners.

• Safety – not comfortable going out and running at night? A treadmill is a good alternative.

• Reduce injuries – ironically, treadmills might be easier on your joints than concrete.

• Mental training – if you can go long distances on a treadmill when there is nothing to distract you, it is sure to build your resilience for races.

Cons of a treadmill

• Less time outdoors – being outdoors is good for your mind, not just your body. If you are replacing your runs with treadmill sessions, you might get the same physical boost but you’ll miss the mindfulness boost.

• Not race-specific – both mentally and physically, it is good to practise under race conditions. If you have an event in mind, or are trying to set a personal best over a specific distance or course, then try to replicate it at least some of the time.

• Boring – sure, the monotony could build resilience, but eventually it may be so boring that you stop running altogether. Stay motivated by getting outdoors or running with friends.

Things to consider

A common injury is repetitive strain. So, whatever your preferred mode of workout is, you should vary the sessions. Consider doing both treadmill and outdoor running, or adding other cross training elements like swimming, cycling, rowing, hiking or HIIT sessions.

Add incline running or power-walking to your sessions. You can do this on a hill or on a treadmill. This will improve your fitness, without the jarring on each stride.

Strength training will improve your running and decrease your risk of injury. Your posture will improve, making you a more efficient runner.

The running you do is better than the running you should do but don’t – if you like running on a treadmill and are therefore more likely to do it, then hit the treadmill no matter what anyone tells you.