In my previous post I provided some data on how my own stride rate and stride length vary with running speed. In that post I referenced another article on running cadence by Alex Hutchinson – I sent Alex my data, and he went ahead and added it to a graph that he had compiled showing stride frequency/rate vs. speed for himself, Amby Burfoot, and a group of runners from a study by Peter Weyand. Here’s the result:
What this graph shows is that for any speed, my cadence (purple line) is higher than that of both Alex and Amby, as well as the average of the individuals in the Weyand study. Putting aside the fact that this graph compares me, a college professor who just barely qualified for the Boston Marathon, to a former winner of said race, as well as to a former middle distance runner for the Canadian National Team (Alex), the big question is why does our cadence vary so much? Is it because Amby was on a treadmill? Maybe, but I suspect not, since Alex also recorded his data on the road. Could it be that my tight leg muscles limit my hip extension and thus stride length, forcing me to rely on a higher cadence to maintain speed? I suggested this, and Amby’s response was to challenge me to a “flexibility” match. Apparently he suffers from the same tight-legged affliction. Perhaps it’s body weight – I’m pretty certain that my BMI is quite a bit higher than either of theirs. Maybe it’s our form – Alex admits to being a bit of an overstrider. Maybe Amby’s stride is longer because he’s a bit taller, but I’m not sure what Alex’s height is (there is some literature on how/if anthropometric measures influence stride length which I hope to get to in a future post). Maybe it’s just the structural makeup of our muscles and tendons – perhaps at an individual level they simply are most efficient over a certain range.
In a follow up post on his own Peak Performance blog, Amby provided a table with additional comparisons, and he included a data point from Usain Bolt, making me feel even more inferior than I already did among such lofty running company. Here is Amby’s table (with some added numbers from my own dataset):
|
PACE |
Amby |
Peter |
Alex |
Usain |
|
10:00/mi |
172 |
178 |
|
|
|
8:30 |
176 |
182 |
|
|
|
8:02 |
|
185 |
164 |
|
|
7:30 |
180 |
186 |
|
|
|
7:00 |
|
190 |
|
|
|
6:40 |
184 |
191 |
|
|
|
6:26 |
|
195 |
170 |
|
|
6:00 |
|
198 |
|
|
|
5:37 |
|
212 |
178 |
|
|
5:00 |
|
208 |
188 |
|
|
4:49 |
|
220 |
|
|
|
2:57 |
|
yeah right! |
|
257 |
Amby very correctly points out that though the varaition in these numbers are interesting, they don’t necessarily tell us much about performance. Amby writes this:
“So I said this column was about oxygen consumption, right? Here’s why. All the stride stuff doesn’t tell us much. After all, there are no gold medals for highest-stride-rate, or Peter, a 3:15 marathoner, might be a contender in London next summer. They give gold medals in distance racing for maintaining a fast pace for long distances, which is closely related to oxygen consumption at a given speed.”
And he’s absolutely correct. I will make the bold statement here and now that despite my wiley coyote and the road-runner like cadence, I will not win the Olympic Marathon next year! The reason? I’d venture to guess that it’s all about physiology. Form is part of the equation, but perhaps only a minor one when it comes to performance at a broad level. A minor tweak might make a difference for a runner who has elite physiology already, but no form change is going to allow me to win, or even ever have a hope of competing at anything more than the local race level. When I look at what elite marathoners can do, it seems like magic. The thought of being able to run 26.2 miles at sub 5:00/mile pace is mind boggling, as I can barely eek out 400m at this pace. I simply do not have the necessary cardiovascular, respiratory, and muscular physiology to handle this kind of pace for a long time. Perhaps if I lost 30-40 pounds I might be able to stretch the distance at that pace out just a bit, but I can assure you that I’ll never be breaking the finish-line tape in first place at a major marathon.
Where all of this cadence business might matter though is in terms of injury risk. For recreational runners like myself who aren’t trying to squeeze out every last bit of speed from our legs, tweaking cadence does seem to have potential to reduce the dreaded overstride, which in turn might reduce loading on the legs a bit. But, altering cadence can be really tough, and requires consistent practice, since the body tends to fall into a comfort zone due to muscle memory. Changing cadence feels really awkward at first, and thought there are studies that have shown that better impact moderating behavior can be learned and consolidated, I can’t recall if any have specifically looked at cadence. To be honest, I wish I knew what my cadence was 2-3 years ago, because I have no idea if mine has actually changed, or if 180-184 has always been my easy-pace comfort zone. I think we still have a lot to learn about all of this, and I love the continuing experimentation!
Thanks to Amby and Alex for adding to and continuing this discussion!
You might also like:
Acclimation to Running in Minimalist or Barefoot-Style Shoes: Is Form Change Instantaneous, or Does it Adapt Over Time?
Running Form in Recreational 5K Runners: Slow Motion Video
Running Form at the 2010 Boston Marathon: Slow Motion Video of Barefoot, Minimalist, and Traditionally Shod Runners at sub-3:00 Pace
Gait Variability Among Elite Runners at the 2011 Boston Marathon
Movement Signature of the Gravity Intolerant Runner – The Importance of Swing Phase
About Peter Larson
Interesting post, which really shatters the myth that 180 steps per minute (i.e. 1.5 strides per second on the above graph) results in optimum performance. This value would be on the upper end of Burfoot’s range (though it would be interesting to look a video of Amby running his 1968 Boston Marathon 2:22 win; I suspect he obtained his former pace both with a higher cadence and a longer stride) where-as it is at your low end. What I find interesting, particularly looking at Weyland’s and your upward tilting curves at highest speeds is the implication that many (?) runners’ incremental velocity gains at their fastest sprint speeds is obtained more-so via a faster cadence than a longer stride. It would be interesting to study comparable data as you four have provided over a broader range of runners.
In any case, having recently obtain a Garmin footpod to equivalently measure my own stride frequency versus pace it occurs that a treadmill test, versus a road test with data sampled over a much longer period of time, results in less accurate and meaningful data – owing to the inherent springiness of the treadmill’s bed, the absence of wind resistance, and the runner’s increased consciousness of their cadence being measured (i.e. the Hawthorne effect). As a knowledgeable specialty running shoe representative recently told me: “Any over-striding heel-striking runner can consistently land on their mid-foot when running the length of the store.”
Yes, the other thing about a treadmill is that you really cannot skid into your landing because the belt is actively moving toward your foot. I see a lot of people whose feet are still swinging forward a bit at contact on the road, but this seem to be rare on the treadmill. If you get a dataset send it to me Mark – I can let you know how I got mine off of SportTracks if you’d like – had to download a plugin.
Pete
Hi Pete,
“Yes, the other thing about a treadmill is that you really cannot skid
into your landing because the belt is actively moving toward your foot.”
Um… whether you are running at x m/s over static ground, or running on a readmill that is moving at x m/s the relative motion of the foot w.r.t to the surface should be the same both situations.
To make this clearer, stick a treadmill on the back of pickup, drive it at x m/s, have the treadmill go at x m/s, and the belt of the treadmill should be zero matching the speed of the ground. The speed of the runner of the runner is the same at x m/s, and the landing surface is the same at 0 m/s, so it’s exactly the same as runner who’s is running alongside the pickup matching it’s speed.
However, I wouldn’t be surprised if observations about gait a different between a treadmill and out on the road, but relative speeds won’t be the reason. Instead you’ll look deeper at the subtle differences such as wind resistance and surface, fatigue etc.
Robert.
Robert,
Comparing a treadmill to overground always baffles me for some reason! It feels completely different to me, beyond just wind resistance. Could it be that the belt changes speed slightly with every impact? This is why I need engineers like you to comment here!
Pete
In 1996 it was found in the U.K. (see link to ncbi.nlm.nih.gov… that a runner needs to set the treadmill at one-percent grade to match the energy needed to run at that same pace outdoors, owing both to the absence of wind resistance and the completely predictable treadmill landing surface (which if employed outdoors would risk tripping!) Purely subjectively I’ve found several treadmills at my fitness center which provide a very bouncy bed. While I’m sure the designers of such treadmills hoped to reduce the likelihood of injury via minimizing peak landing forces of the limbs and joints, the result is that a one-percent grade doesn’t come close to my outdoors exertion at the same speed. So, on such bouncy treadmills I’ve learned to set those grades to 1.5% and sometimes 2%, based solely on my feel. It’s my guess that the bounciness of such treadmill beds encourages runners to develop an bouncy gait, but the runner can reduce this likelihood by being cognizant of their environment while running and maintaining a relatively high cadence.
Hi Mark,
The amount of incline you’ll need to replicate the cost of wind resistance will vary according to the speed you are trying to replicate, so a single value wouldn’t be appropriate. The force of wind resistance goes up by the square of wind speed, so double your speed and you’ll have four times as much drag, and for small inclines the amount of incline for doubling the speed you’d need to quadruple the incline.
You also mention about the vertical elasticity of the treadmill effect things, and I would have thought that this will be the case, how much it might help or hinder your efficiency will depend on how it effects your gait and the forces you are applying and the energy loses associated with this vertical deformation. It’s a complex system so could go either way and likely vary at different paces, so I’d can’t really make an educated guess whether one should incline the treadmill for it’s elastic properties – to answer this one would need to do experimentation like done in the paper you highlighted. One thing for sure though – not all treadmills are the same so you’d need to calibrate separately for each type.
Robert.
There is some literature comparing treadmill vs. overground mechanics. Yet another topic to dig into!
Hi Pete,
“Could it be that the belt changes speed slightly with every impact?”
I think it’s inevitable that we would slow the belt on landing and speed up on toe off. This would be partly down to mechanics of the drive system and elasticity of the belt.
This little bit of horizontal give on landing would result in less time that the shoe/foot and belt are moving at different speeds so the shoe/foot would scuff the surface for less time. Whether this fully explains what you have observed or not I can’t say, but I’m sure it’ll be part of the reason.
Robert.
One difference is that on the ground, you control (and perhaps vary) your pace with each step, while on the treadmill, the pace is dictated to you.
Sure, you can control the treadmill motors, but from your legs’ point of view, their pacing is determined primarily by the moving surface below them, not by your brain. That’s huge.
Good point – very little variation means keep up or fly off the belt!
So I’m not totally against treadmills. Runners-in-flight make for amusing youtube videos.
I think that the discussion of speed is a bit of a red herring, at least if our main goal is longevity/health in running. We should rather look to those who have run from youth into old age.
I also suspect that cadence is a lagging indicator of form. In other words, the way to improve form is to focus on whatever we think constitutes good form (I’d say: bend knees, stand tall, pull up with feet, keep hips forward, land with feet under you) rather than to actively “step faster.”
180 may not be an absolute rule. But what is? Still a good rule of thumb, for most people, under most conditions.
Pete,
At my normal running pace of 7:30 my count is about 195. For shorter intervals on the track it goes up to around 210. My last 5K (17:15) avg’d 200.
As for count vs Oxygen consumption I don’t think it’s a direct comparison, but something you can train. It might be the same as seen in cycling. Lance Armstrong after his cancer had to raise his cadence to 120 rpm due to the loss of muscle mass vs. the normal 90-95rpm. It was interesting to watch Lance vs one his man rivals, Ulrich, going up the hills. Lance would be almost dancing on the pedals, while Ulrich was muscling his way up at a much lower cadence. Both guys had considerable success with vastly difference styles.
Interesting stuff as always, Pete. For the record, I’m about 6′ 0.5″ (that 0.5″ is very important to my self-esteem!), so a bit more long-legged than average. I’m definitely looking forward to your post on how/if anthropometric measures influence stride length. It seems intuitively obvious to me, but I’m not foolish enough to rely on “intuitively obvious” when there’s data out there!
For what it’s worth, my favorite short-vs-tall battle was Geb v. Tergat in the 2000 Olympics. This clip shows them duking it out in slow-mo, and it’s clear that Tergat has a longer stride: link to youtube.com…. So that’s n=2, which is twice as good as n=1. :)
So I am a bit shorter than you and Amby. However, the literature seems to suggest little correlation between height/leg length and stride length at a given speed. I’m guessing muscle/tendon properties may be most critical.
Im 6’4” and run with a friend who is 5’2”. There is no way i can comfortably match her cadence at any speed that we can both maintian. And I imagine it would be next to impossible for her to match my stride length. We both use different parts of the equation to get the resulting speed.
I must say i find it very difficult to believe that there is no correlation between height and stride length at a given speed.
Increased leg length would suggest a longer pendulum that you require to swing through as you go through a stride cycle. a shorter pendulum allows you to cycle through faster, a longer one takes longer… which should result in a higher cadence for shorter runners…. and if the cadence is different then the stride length must also be different to achieve the same speed.
Still as you say in your recent post on the new sketchers, ill try to keep an open mind.
I felt the same way, but the data are out there…just need time to write up a post on the topic.
Just got around to really digesting this latest series of posts on running cadence. Again, really strong discussion on something that seems to be getting quite a bit of coverage. I tend to agree with Paul above that height/limb length plays a big role in determining the most optimal cadence for each individual. I too have done some impromptu experiments while running several races including a few half marathons. I would run behind different people and try to match their cadence while we ran at the same pace. The shorter individuals tended to have the faster leg turnover while the taller ones (like me at 6’4) had slower cadences. Again, very non scientific, but still, educational for me.
I would love to know what data set or literature you refer to regarding leg/stride length.
Oh i agree that the flight time also plays a deffinate role in the stride length.
When i womble along at 6:00/km at a specific cadence i am exerting little force in my extension, and have a relatively short air time and a short stride lenght.
If i retain the same cadence but increase the pace i do it by applying more driving force, increasing the air time and increasing the stride length.
As the pace continues to sharpen there will come a point where the energy required to increase the driving force is higher than the cost to increase the cadence, and thats when we start to increase cadence.
Ultimatly i agree that its complete humbug to prescribe a magic cadence that is optimal for everyone… In my mind you cant even do that for a single person… but there is almost certainly an optimal function that describes how match increase in cadence to increase in driving force to maximise efficiency during running.
but its also clear that many runners (and ill include myself there as well) often overstride, And increasing your cadence makes a very good que to help avoid that.
It’s important to note that flight time also contributes to stride length. So, a person with short legs who generates a lot of power on pushoff and thus a lot of air time may have quite a long stride.
I truly enjoyed reading this post. I don’t often think this analytically about my own running (I try to leave my statistics “day job” mostly at the door when I run), but my inner data geek never really rests. Thanks for the detailed discussion!
I love this post because it shows that the stride rate just depends and there is no magic number. Thanks for the detailed analysis!
Forgetting about what is ideal (some count on stride rate more the stride length and vice versa) I think the important thing to note is the simple fact that it seems the faster we all go the quicker the turnover so it is good to work at a lot of different speeds from easy down to race pace. Often our training is done too slow and then too fast, not much in between. Now forgetting about any physiology, which I love to read and learn about, thinking about running as a rhythm exercise, like a dance, is a simple way to break it down. You can’t get to the the performance without working the steps in between and adding more moderate paced workouts can make the transition to a quicker step much more comfortable.This post confirmed my thinking about training paces and how I explain them to my athletes – comparing running to other things they do, working on a jump shot, playing an instrument, or learning a dance, where they really do practice at different tempos to get it down. I coach kids so I am always trying to find ways to make it easier for them to comprehend, and for my own training too. I see some coaches teaching them to run 15 steps (per leg) every 10 seconds and to me it seems forced, especially for those not at 180 for that pace – running next others of different abilities. So I say who cares, eh, I’m too curious… how about, don’t stress about what the (best/elite) stride rate is! Just know it is different the faster or slower we go so work at many different speeds, do drills, plyos, and hills to improve muscle tension and strength to possibly improve stride length and ground contact time. Without even consciously attempting to turn the legs over faster they’ll do that on their own after adapting from a varied run and strength training. Also, along the way you’re feeling good about running slow, medium, and fast because you recognize how they are connected and support the goal of running at X pace.
I agree – I find it helps a lot to “feel” each cadence and get used to that feeling. I think it is possible to have a cadence that is too low, particularly for an overstrider. But, unless you are really reaching with that lower leg, I think aiming for a particular target cadence may not make much sense. I definitely have my comfort zones, and my cadence obviously shifts pretty regularly with speed. My question though is why mine is so darned high!
Hi Pete,
One question that popped into my head on both of your two last posts is how you cadence has changed over the few years – and you go pose this question with no answer at the end of this post…
Do you have any video footage from the past that you could look at? I would also be interested in your ground contact/time in the air, and the distance you were landing in front of the centre of mass. From video footage you might be able to gleen some of this info, and have a bash at estimating the speed as this give you a one data point on which to compare your recent results.
Whilst out on a cycle I was pontificating on the topic of cadence, time of stance, time in the air, G loading it occurred to me that we might be able to use the accelerometer’s in our modern phones to be estimate all of this. When in the air our G loading will be zero, and on stance it will be non zero, so from this one will be able to compute the time air and stance right off. The curve of the G loading on stance would be interest, while it won’t correlate directly with that of vertical GRF it won’t be far off.
Is there are phone apps that do this? Or simply an app that records the G loading in way that we can download? Once we have the G loading the rest of the data is pretty straight forward to compute.
Robert.
isnt this simply an issue of power? a high cadence/lower speed just means you dont have the muscular power to propel yourself at a greater stride length. perhaps im oversimplifying.
For most people, the specific combo of cadence and stride length adopted is the one that minimizes metabolic cost. Having too long a stride can have negative consequences, so there is more to it than just the ability to propel yourself forward.