We often use treadmill running for gait analysis. It is a big thing at the moment with most running and and sports stores offering some form of “gait analysis”, some more in-depth than others. For a good blog post on “in store” gait analysis take a look at Matt Phillips blog Why Gait Analysis Won’t Help You Find The Right Shoe. But (and it’s a big but) how many of us run exclusively run on treadmills? How many of us don’t run on treadmills at all? If we don’t run on treadmills, but we buy trainers based on a treadmill running assessment, is it the same as running overground?
There are several factors that could be considered if we ask the question: is it the same? We could be talking about the aerobic capacity or the biomechanics, or the physiological demands of the type of running. Briefly, Bassett et al. (1985) found that the aerobic requirements of treadmill running versus overground running on a level and inclined surface were not statistically different. For the purpose of shoe selection or of gait analysis for running technique and style we are more interested in the biomechanics, or more specifically the kinematics (the study of movement from a geometrical point of view), of a persons running style.
The catalyst for me writing this post is the image above, which comes from a gait analysis session with a patient of mine (permission to use the images in this post has kindly been given by the patient). Before we get going I should point out a few important points:
- In both scenarios the patient was instructed to run at their “steady run pace”.
- On the treadmill they were given chance to acclimatise to their preferred pace.
- They were also used to running on treadmills and performed a mix of treadmill and outdoor running during their training.
- The gait analysis was not in relation to a particular injury, more from a running economy and performance perspective.
You can see if we just look at the foot strike (point at which the foot contacts the running surface), the two images are quite different. On the left we can see that the foot lands fairly flat, on its outside edge, whilst on the right the foot lands on the heel in a straighter position. Not so easy to see in the image, but which was evident in the video, is that the step width is much narrower on the left compared with the right. Nigg et al. (1995) made a kinematic comparison of overground versus treadmill running and found that subjects adapted their landing style on a treadmill so that the foot landed in more of a flat position than in overground running, which is what we see here. Nigg et al. also found that most of the other variables studied showed an inconsistent pattern based on a individuals athletes landing style, running speed and “shoe/treadmill situation”.
But what about the rest of the body? It is important to look above the foot during gait analysis, so who does this individuals running form vary between the two scenarios? We can see that the shoulders and hips are level with the treadmill running, whilst there is a contralateral (opposite) hip drop with the overground running. What was also visible in the video comparison was the amount of sided-to-side head movement was reduced during treadmill running compared to overground running. This may be due to the constraints of the treadmill leading to a tighter/more uniform control on running form and stride rate (Lindsay et al., 2014).
So what does all this mean?
Well it tells that the running on a treadmill is not the same as running overground. Also that if you are someone who predominantly or exclusively runs overground, treadmill gait analysis is possibly not a true reflection of your running form. In terms of shoe selection Nigg et al. summarise things quite nicely:
“…individual assessment of running kinematics on a treadmill for shoe or orthotic assessment may possibly lead to inadequate conclusions about overground running.”
My view is that gait analysis is still a useful tool, it can help to see how you run, which is quite often different to how you think you run! But if I have a patient how predominantly runs overground and not on a treadmill, this is how I like to see them run and vice versa. With regards to shoe selection, use the time on the treadmill to see how the shoe feels, really just ask yourself: Is it comfortable? If it is then that is a good start.
I hope you’ve enjoyed this post and if you have any questions, feel free to get in touch.
Thanks for reading.