Previously I talked about the stride length of 400m hurdlers, 800m runners and 10K runners. I thought it would be interesting to have a look at Eliud Kipchoge – the world’s premier marathoner.
Kipchoge is famed for his excellent running form and economical stride and in Oct. 2019 he became the first man to run a marathon in under two hours. I found footage of the run on Youtube and watched a section from the last kilometre to calculate his stride length.
How to calculate stride length manually
You can skip past this section if you’d rather not get into the details
As we know Speed = Stride Length x Stride Frequency. We can rearrange that as Stride Length = Speed divided by Frequency. And because Speed is actually the distance covered in a time period (e.g. miles per hour); we can convert it to a Pace (e.g. 15mph is 4min/mile because 60mins / 15 = 4).
We need to find out how fast he’s running and how many steps he’s taking in a set period to be able to calculate the stride length.
Step 1 – Watching the footage I found a section where the camera showed Kipchoge for a decent length of time; the longer the better as it gives a more accurate sample. The particular segment lasted twenty seconds.
Step 2 – I counted the number of times his left arm swings. It doesn’t matter whether you count armswings or footsteps they’re going to match. Generally though I find armswings are easier to count. I counted thirty armswings.
Step 3 – As this was a twenty second clip, I had to triple it to get the cadence for a minute (3×30 = 90). But this was only for the swing of one arm so I doubled it (90 x 2 = 180) to get the total for both arms. Given arms and legs swing at the same rate, it gives the number of steps per minute – 180. Very conveniently it’s also three steps per second.
Step 4 – The marathon was run in 1:59:40 – an average pace of 4:34/mile. I remember Kipchoge was very consistent in his pacing so I’ve got a high level of confidence that his is how quick he was covering the ground.
Now I calculate how many steps Eliud covers in his 4:34 mile. In four minutes he covers 720 steps (180×4) and then in the remaining thirty-four seconds takes another 102 (34×3) for a grand total of 822 steps per mile.
Step 5 – As a mile is 1,609 metres and we know Kipchoge takes 822 steps to cover it, it works out that his stride length is 1.96metres (1609 / 822).
NB This final step has an implicit conversion from Imperial to Metric measuring systems. I could have gone metric earlier as I know he was running at 2:50/km, so he was taking 510 steps per km (1000/510 = 1.96) to get the same stride length.
Kipchoge’s Stride Length
If you skipped straight down here, let’s recap …. at his marathon pace of 4:34/mile, Eliud Kipchoge is taking 180 steps per minute with a stride length of 1.96 metres. What’s interesting, and defeats those people who say they have little legs, is that Kipchoge is only 1.67m tall (5’6”) – his stride is over 15% longer than he is tall.
I also found video of 18-year-old Eliud Kipchoge winning the 5000m gold at the 2003 World Championships in Paris. His running form looks a little less smooth than these days but he was still able to win in 12min52. I counted steps for one of his 400m laps close to the end of the race – he completed it in a touch under 1min05 – a pace of 4:21/mile. He took 202 steps and that works out to a stride length of 1.83 metres. Surprisingly it was shorter than he ran for a whole sub-2 marathon but may begin to explain why his form looked less smooth.
Nonetheless whichever race you look at Kipchoge’s stride length is bigger than he is tall and that’s worth thinking about.