On my running research kick, hopefully for a few more weeks. Here is another research article on running. It is called, Hip Muscle Loads During Running at Various Step Rates, Lenhart R, et al, JOSPT; 10(44), 2014,pp 766-774
This study is looking to see how the hip musculature activity changes with running at 3 different cadences. In a previous study, it was found that increasing your running cadence by 10%, for example if you run at 140 steps/minute, increase that to run at 154 steps/minute, you will decrease the load on the hip joint. This article looks at how this actually occurs. Which muscles take more of the load and which muscles take less of the load.
The authors hypothesized that a higher cadence would “...increase hamstring and gluteus maximus muscle loading … but decrease loading of the gluteal muscles in the early stance”.
To do this the authors got 33 healthy runners, i.e. no injuries in the previous 3 months. The runners went running on a treadmill and their preferred cadence was found out. Then each participant was asked to run at 90%, 100% and 110% of their preferred cadence. This was controlled by using an audible metronome (one of those things that keep time in music). Once the runner was able to maintain the new cadence for at least one minute, the researchers started collecting their data. And yes, they used a lot of fancy equipment to collect the data.
What did they come up with? One thing that was figured out, was that the average cadence of the 33 runners was 174 steps/minute.
Their hypothesis was correct. As running cadence increased, so did muscle activation of hamstrings and gluteus maximus, in late swing phase. That is the phase, when your leg straightens out in front of the body, right before your foot touches the ground. After your foot touches the ground, you are in early stance phase. When your foot is underneath the body, that is called mid stance phase. In early stance phase, there was a decrease in the loading of the deep gluteal muscles and piriformis. This is important as both of those muscles can be the cause of running injuries.
When increasing your cadence, you would usually land with your leg being a little straighter, this is thought to be the cause of the decreased load on the gluteals and piriformis. Interesting to note, is that the largest force generated by any muscle in this study was the gluteus medius muscle. For the gluteals as there was a increase in cadence, there was proportional decrease in load. That is with a 10% increase in cadence, there was a 10% decrease in peak force from each gluteal muscle. And that was different from the piriformis muscle. For the piriformis muscle, a 10% increase in cadence “...resulted in a 14% average reduction in peak piriformis force”.
Not all muscles had a decrease in activity though. For example, the hamstrings and gluteus maximus had increase in activity with increased cadence. This makes good sense as well. These are the muscles that slow down the leg when it swings forward, when running or walking, just before your foot touches the ground, late swing phase. If you increase your cadence, the number of steps per minutes, you have to swing your leg through faster. If your leg is swinging faster, it would require more muscle activity to slow it down. One interesting fact brought up by the researchers is that even though, running with a higher cadence increases the strain on the hamstring muscles, the strain on the hamstring muscles is less than 60% of the strain present during sprinting. This allows the strain to increase but still keeps the new level of hamstring strain well below what is thought to be load levels associated with hamstring muscle injuries.
The work done by the muscle can be classified as either negative (eccentric) or positive (concentric). Negative work or eccentric work is done with slowing down the body or a lengthening of the muscles. Whereas positive work has to do with speeding the body up or a shortening of the muscles.
Based on seeing how the muscles work during running, the authors recommend “[a] rapid-repetition stretch-shortening activity of eccentric contraction (negative work), followed immediately by concentric contraction (positive work)...”.
What are some examples of exercises that follow this pattern of contractions? For the hip flexors you could try doing some A skipping running drills.
For the hip flexors and hamstrings try some B skipping (this is frickin’ hard to get arms and legs coordinated).
For the glutes you could try split-squat jumps.
Check out how to perform A skipping and B skipping in the video below by Legacy Endurance Inc:
Some of the limitations of the this study were that they used generalized muscle models, which would not take into account any type of patient specific muscle abnormalities. Also, not all the small hip muscles, i.e. gemelli, were included in their muscle models, which might give more forces onto different muscles. In addition, all the testing was done at the client’s preferred running speed. Increasing the speed of running may not make these findings generalizable to slower runners. And finally, there were only 33 subjects in the study.
To put this into practical application. The question is how do I run with a faster cadence? One way to do that is to run in a more minimalist shoe.
Let me share my experiences with you. When I was in Halifax, working at CFB Stadacona, I treated a number of soldiers with running injuries. I decided to do a little experiment. What I did was get them to run on the treadmill at their preferred speed. After 2-3 minutes, I would count their cadence. Most of them were around 140 steps/minute. I would stop the treadmill and explain to them what their cadence was. They would say things like, “That is because I was not running at a fast speed”. I would say okay, start running again at the same speed for a couple of minutes, then get them in increase their speed by 1.0 mph. After a couple of minutes, I would recount their cadence, get them to increase their speed again by 1.0 mph and after a couple of minutes, recount their cadence. What do you think I found? Did their cadence increase with their speed? The answer… is… NO! The cadence stayed relatively the same. For example, if they initially ran at 140 steps/min, they might go up to 142 steps/min after the first increase and maybe 145 steps/min after the second increase in speed.
WAIT! Hold on! So what if that is their cadence?! What should someone’s cadence be? According to Runner’s World, I believe this is where I read the article, there is a belief in the running world that the ideal cadence is 180 steps/min. Why 180? Another study was done, the authors calculated the cadence of all the gold medal winners, from 100m sprint to the marathon, at the Olympics one year, added them up and found the average. The average was… you guessed it, 180.
Personally, I like to think that we are all different and a nice cadence, in my books is anywhere from 170-190 steps/min. So how does this work its way into my experiment with the soldiers at Stadacona? Please let me continue…
What I did next to the soldiers, after I let them rest for a couple of minutes. I asked them to take off their shoes and socks. And hop back onto the treadmill. Getting them running again, at their preferred speed for 2-3 minutes and recounted their cadence. What did I find? Most of the barefoot runners were now running somewhere between 170-185 steps/min, automatically! Their cadence would shoot up between 20-30% simply by taking off their shoes! That was a pretty amazing finding for myself. Really interesting. In addition, most of them changed their gait pattern, which is not surprising, all of a sudden their feet had a large change in their neural input. The nerves of the foot did not have to ‘feel’ through an inch of foam, putting shoes on is known to change patterns of how people and animals move.
Here is a cute, little video that demonstrates the effect of putting shoes on someone that is not used to wearing shoes. Why do you think the dogs suddenly change their walking? I think the nerves in their feet are being 'muffled' by the shoes and the dogs do not know how to react.
Another reason, I thought this might happen is because there was less weight on their foot, with no shoe, therefore it would be easier/ quicker to swing that leg without a heavy foot on the end of it. Think of swinging a 20 lb sledge hammer vs. a 5 lb sledge.
My recommendation is to go to a minimal shoe for increased neural input and decreased weight. Both of which will help you increase your cadence. If you go minimal, go responsibly. Do not simply change to a minimalist shoe and keep running your regular mileage. That will lead to more injuries, especially of the Achilles and posterior tibialis tendons. Get a good transition program.
Another thing I tell people is to simply take a smaller, lighter, softer step, when running. This gets people to shorten their stride. If they shorten their stride and keep the same pace, they have increased their cadence!
If you have any other tips or tricks for getting runners to increase their cadence or another running injury prevention tip, please leave a comment below.