Understanding the Impact of Cadence in Running

Dr. Megan Peach // #FitnessAthleteFriday // www.ptonice.com 

In today's episode of the PT on ICE Daily Show, Endurance Athlete division leader Megan Peach discusses the importance of cadence in running, variables that may affect a runner's cadence, the relationship between cadence & speed, and finally the "optimal" running cadence.

Take a listen to the episode or read the episode transcription below.

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EPISODE TRANSCRIPTION

INTRODUCTION Hey everyone, this is Alan. Chief Operating Officer here at ICE. Before we get started with today’s episode, I want to talk to you about VersaLifts. Today’s episode is brought to you by VersaLifts. Best known for their heel lift shoe inserts, VersaLifts has been a leading innovator in bringing simple but highly effective rehab tools to the market. If you have clients with stiff ankles, Achilles tendinopathy, or basic skeletal structure limitations keeping them from squatting with proper form and good depth, a little heel lift can make a huge difference. VersaLifts heel lifts are available in three different sizes and all of them add an additional half inch of h drop to any training shoe, helping athletes squat deeper with better form. Visit www.vlifts.com/icephysio or click the link in today’s show notes to get your VersaLifts today.

MEGAN PEACH, PT, DPT, OCS, CSCS Alright, Instagram. Here we go again. YouTube, we're on. Okay, finally. Sorry about that a couple minutes ago. I think I actually got it to work this time. Okay, we are live on Insta. We are live on YouTube. I am Megan Peach, probably the most technologically challenged person next to Jason that we have in this community. So, I apologize for the previous live feed that didn't actually work. Again, I'm Megan Peach and this is PT on Ice, your daily show. I'll be your host today. I am one of the lead faculty for the endurance division and specifically in the injured runner course, both the live and the online courses. And although our courses have wrapped up for this year actually, We are super looking forward to next year. Over the next couple of months, Jason and Rachel and I are basically doing like a big revamp of Rehab of the Injured Runner online. And so that course is going to look entirely different come January than it does right now. If you haven't taken that course and you've taken the live course already, or even if you haven't taken the live course, this is going to be a great time to hop onto that course, just because the material is going to be really complimentary to the live course, even more so than it has been in the past. And then if you have taken Rehab of the Injured Runner online already, it will be a really good time just to check in because it's going to look entirely different in terms of the material and what's in there. Remember, if you've taken that course already, you have lifetime access for as long as that course exists. And so check in with us in January for a full revamp, full update. We're super excited about it.

RUNNING & CADENCE Okay, so to get to today's topic, I wanna talk about cadence. And cadence is something that I think if you treat injured runners at all, if you have in the past or you've taken one of the courses, This is a topic that's pretty familiar. It's a running gait retraining tool that we use probably more than any other tool that we have in our gait retraining toolbox. And it's used for a variety of different injuries. We could use it globally for injuries like patellofemoral pain or IT band syndrome. exertional compartment syndrome. There are even prospective studies that have looked at healthy runners and the risk factors for their injuries. And they've seen that low cadence is a risk factor for things like bone stress injuries, things like medial tibial stress syndrome. So we can use it not only to treat injuries, but then potentially as an injury prevention tool as well when somebody has a really low cadence. And then we can also use cadence retraining as a way to treat really specific gait abnormalities or mechanical faults after we've done a running gait analysis. And so typically when we are using cadence as a gait retraining tool, we're increasing the cadence by at least 10%, at least that's the goal typically. And when we increase somebody's cadence, what we typically see are first, changes at the knee joint. At least those are the most prominent changes that we would see in a runner. And the changes we see at the knee joint are things like increased knee flexion at initial contact. We see a decrease in stride length, or a decrease in foot to center of mass, in terms of where the foot falls in relation to the center of mass. We also see changes at the ankle joint, not as prominent as the knee, but we still see them there. We see with an increase in cadence, we see a relative increase in plantar flexion. So whereas we might see a lot of dorsiflexion with a very slow cadence, we see relatively less or more plantar flexion as that cadence increases. Or you could look at it as less angle of inclination as well. We also see changes at the hip. Again, not as prominent at the knee, but they're still there. With an increase in cadence, we will see increased hip flexion also at initial contact. Not only do we see kinematic changes, but we can see kinetic changes while somebody's running as well. And so some of the kinetic changes that we'll see are decreased vertical loading rate with an increased cadence, as well as decreased vertical center of mass, which can then translate to decreased overall loading for that runner with each foot strike. And so while some of those kinetic variables aren't always accessible to us in a clinical setting, typically they're just lab-based variables. we can still use cadence retraining and still make some of those assumptions that it is going to affect some of those kinematic variables as well. So we can not only use cadence as a gait retraining tool to treat specific injuries, we can use it to treat kinematic variables, but we can also use it to treat kinetic variables.

VARIABLES INFLUENCING HABITUAL CADENCE What I want to talk about and spend the rest of the time today talking about is some of the variables that might influence somebody's habitual cadence that we don't normally discuss or sometimes don't even consider when we are using cadence as a gait retraining tool. And so somebody's habitual cadence, it just means that the cadence that they're running at normally, without any outside influence, without anybody saying, you should run at this cadence, or you should run at this cadence, or you should increase your cadence. It's just their normal everyday cadence that feels good to their body. And so some of the variables that might influence that are leg length, running experience, BMI, as well as speed. So leg length plays a role in that somebody with a shorter leg length, typically has a faster cadence, and somebody with a longer leg length typically has a slower cadence. Okay, now there's obviously a very wide range of a spectrum there in terms of cadence and leg length, and so these variables are typically related to cadence only at, or I guess more strongly, at the ends of the spectrum. So somebody with either very short legs or very long legs their cadence is likely a little bit more related to their leg length than somebody whose leg length sits kind of right in the middle or maybe that like middle 50% range. And so none of these variables are going to apply to everyone, obviously. The next one, so running experience can play a part as well. Somebody who has less experience running, so like a novice runner, typically has a slower cadence. I've definitely found this to be true in clinic versus somebody who has a lot of experience running or who is a very high level runner, maybe even a professional runner, typically has a very high cadence, upwards of mid 180s, upper 180s, maybe even low 190s, depending on that runner. I've definitely found that variable to be true within clinic, but again, Take that with a bit of a grain of salt because the ends of that spectrum in terms of novice versus experience tend to ring more true with a relationship with cadence than the middle of that spectrum for experience. BMI can also play a role in that somebody with a greater BMI tends to have a slower cadence versus somebody who has a lower BMI tends to have a bit faster of a cadence. That one, clinically, I really can't speak to that one, but that's what's in the literature.

SPEED & CADENCE All right, and speed is the last variable that I wanna talk about because I think intuitively, we know that speed is related to cadence, and that's true to a certain respect. And intuitively, if we think of as somebody speeds up their pace, then their cadence is going to speed up as well. And that's true, but only to a certain extent and really only to higher speeds. And so for most people, their cadence is going to speed up only as they approach sprinting or a very, very fast run. And so when we think of speed and we think of running pace, We have two different strategies that we can use to increase our running pace or our speed. And one of those strategies is to increase the stride frequency or increase the cadence. So we increase the number of times our legs turn over, and that alone can increase the speed. The other strategy to increase speed is an increase in stride length. So rather than increase the stride frequency, we can also increase the stride length. And when we increase the stride length independent of any other changes, we can actually increase the speed even when we're maintaining the same stride frequency or cadence. So if we are using these variables independently and considering them independently, most humans are going to take the stride length strategy first up until they get to a point where they're almost sprinting. So a very fast run, a very high intensity run. And at that point, then they're going to employ more of a stride frequency or a cadence tactic to increase their running pace or running speed. So let's think about when you have an injured runner on a treadmill and you're choosing to use a cadence gait retraining tool to address either their running-related injury or certain gait mechanics, and you get them back on the treadmill, and you're having them run at their 6.0 mile per hour, whatever they did their running gait analysis at, and you say, okay, I want you to run at this new cadence, and you've increased their cadence, and now you have it on a metronome, and you put the metronome on the treadmill, and they hear that click, click, click, click, click when they're running, and the first thing they do I think you've all experienced this. If you have treated injured runners before, the first thing they do is that they increase the speed on their treadmill, right? So why we don't want them to do that is that if they increase that speed on the treadmill, chances are they're also going to employ this increased stride length strategy to increase the speed. They may also increase their cadence as well, but we have to remove some of those variables. If we keep them at the same speed that they did their running gait analysis, which should be a fairly comfortable speed for them, something they would run just an easy run, or even a moderate run, but let's say we have to keep them at that same speed that we use for the running gait analysis while we're using that increased cadence, then they have no choice but to increase the cadence rather than increase their stride length. We don't want them to do that. If they increase their stride length by increasing the speed on the treadmill, what's going to happen is that they're likely going to reach out further, meaning they're going to increase their over stride, which is definitely a variable we don't want to influence negatively. We want that over stride to reduce. They may get increased knee extension at initial contact, which again, not a gait mechanic that we want to encourage. We want to encourage more knee flexion at initial contact. We also want to encourage more or less dorsiflexion at initial contact, more plantar flexion, relatively speaking, which is likely also going to increase in the negative direction if we increase the stride length by increasing the speed on the treadmill. All of these variables are very much related in terms of the gait mechanics and the speed of the treadmill and which strategy they employ to actually increase that running gait speed. But if we take out the speed component and just leave that pace at the same pace on the treadmill, then they have no choice but to then change their cadence to match the cadence that you've chosen. And in turn, what we're hoping to see is a positive change in their gait mechanics.

"OPTIMAL" CADENCE" Now we often get a question in both courses of what's the optimal cadence for a recreational runner, and really there isn't like a set in stone, everybody's gotta run at this cadence. It's a range, anywhere from mid 170s to mid 180s is typically what we kind of range for for a recreational runner. It may go higher than that. For a more experienced runner, I find that they can tolerate higher cadences, for a very novice runner, generally sometimes they don't even tolerate like a mid 170s and so although it might be a goal, it's something that we may have to work up towards in the future and with different gait retraining strategies. Okay, so I hope that helps. I hope that clears things up for some cadence questions that we commonly get in both the rehab online and the rehab of the injured runner live. I hope you have an awesome Friday and a great weekend and we'll see you next time.

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