Rate of force development is an important concept to understand. Strength is important, and power is important, but being able to produce force quickly may be even more important.
Here are some thoughts on how to use RFD with patients and athletes.
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#AskMikeReinold Episode 305: Understanding Rate of Force Development
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Transcript
Luke:
Yeah, it’s Luke, for question today we have Bobby from Arizona. Bobby says, “hey everyone. I’m hearing more about focusing on rate of force development and not just strength and peak power. Is this something that you work on at Champion and any advice on how to get started?”
Mike Reinold:
Luke? I mean dramatic improvement from your first episode. I mean that was a dramatic read right there. That was… you know what, I mean, I wish we had somebody that edited this for us, because we could add some dramatic music to you asking that question. I think that would really flow for the episode. But great job Luke. I’m impressed. So all right, rate of force development, right? I’ve been hearing a lot of people talk about this on the internet a little bit. And again, I think it’s great that the physical therapy world is getting more specific with what they’re trying to do. I like that we’re not just working on strength, we’re not just working on power. We’re actually going to get a little bit deeper there and how fast can you produce that power? That’s actually some pretty cool stuff because that is, I think one of the things that the strength and conditioning world does really well, right? And they work with their athletes really well.
Mike Reinold:
I like that physical therapy is getting into that concept as well. We’ve seen that a bit online a little bit, right? Why don’t we talk about it from both lenses, right? So Len, you want to maybe start, because this is something we do with, it’s talked about a lot in like ACL reconstruction and return to play stuff and those types of things, but what’s your thoughts on radar forest development in the rehab setting, right? And when or if, do you even start to focus on this in the rehab setting?
Lenny Macrina:
Right. Yeah, no, I think now that it’s becoming more affordable to have force plates and being able to measure this stuff in a PT clinic and not just in a lab, we probably need to start understanding this better. And I am actually still trying to understand it more and follow people on social media that probably are a little bit more advanced in their thinking with this stuff. And it’s great to have kind of a new thought process on this. So I think now that we use the vault system to be able to measure and we use a handheld dynamometer called a dynamo and we can look in our… And we used to use the force frame as well. And so we can look at the plot of their kick of their extension or their hamstringing kicks and can see actually how quickly they can get to max effort power.
Lenny Macrina:
And I think having that information I think is valuable. We know that when people tear their ACL, it happens, I mean almost milliseconds. It’s like 50 milliseconds after the foot hits the ground, they are in a position where they’re going to tear their ACL. And so do they have that quick ability, that quick power production ability to try to transfer their weight back and get out of that dreaded position of tearing their ACL. And so we can look at during our kicks, how quickly can they obtain max effort quadricep contraction. And I think that’s going to be the key in comparing it to the other side, comparing it to their good side. And you can kind of see a peak how quickly that peak occurs and compare it to the good side and then try to figure out, if this is six months out and you’re just beginning to work on power production because you’ve been working on strength and hypertrophy, you can start to see the peaks are starting to be off.
Lenny Macrina:
They’re off because people don’t have that exact power they can produce. And so we start incorporating that concept into their rehab of creating a faster contraction when they’re doing exercise. So you use things like GymAware, not to throw all these products at people, but GymAware can give feedback on how quickly people can contract that muscle when they’re doing a deadlift or when they’re doing a squat. And I think that those little tools will help the person be able to get that faster contraction, that more power production. So when we continue to measure rate of force development and try to basically make it symmetrical, then I think we feel more comfortable with the person, they feel more comfortable getting back to their sport. Again, where milliseconds of time could mean an ACL tear or not. And so I think we need to be able to get that quick force production returned and restored before we allow our athlete back on the field.
Mike Reinold:
And do you see when people are progressing, right? So let’s say coming back specifically from something like an ACL, like a big surgery like that, do you sometimes see where maybe the ability to produce torque isn’t far off from the other side, but it’s just much slower that they get to that peak torque, right?
Lenny Macrina:
Yeah, definitely.
Mike Reinold:
And is that… I mean, What do you think that is? Is that a neuromuscular thing? Is that a self confidence thing? Is that pain? Is that…
Lenny Macrina:
I would say it’s probably more, hopefully it’s not pain at that point and it’s not a self-confidence thing. They want to be able to do it. It’s just they don’t have the nerve muscular firing to be able to get that. And I think that’s where we come in. So early on in the rehab process, I am constantly, and I’m talking six weeks out when we’re just starting to do squats, a deeper squat, I’m talking about them getting out of the bottom of the squat in the concentric component of it. I want them to think about moving a little faster than they think they should. I want the muscle to kind of get re-educated in that neuromuscular control.
Lenny Macrina:
I mean when we’re talking neuromuscular, we’re talking nerve to the muscle, right? It’s just how quickly is that contraction occurring and it’s delayed, It’s slower in an injured leg in an injured knee. And so I’m constantly trying to get them early on to think about a faster firing of the muscle as they’re coming out of the bottom of the squat, for example. And I think that’s going to get better carryover as we go through the months and months of rehab when we start testing them at 6, 7, 8 months out. That hopefully that earlier concept is carrying over and they can get a better… A faster rate of force, a peak force development.
Mike Reinold:
And to continue with product placements though. But just jumping in there, I mean, we use the Vald force plates as well and I think that’s been one of the things that’ve been excited most about using them as the biofeedback nature of actually allowing the patient to see the graph of their force output in especially side to side. And then you could actually say, “all right, on this next one, let’s get the slope of that curve a little bit more steep.” I mean that’s huge, right? Because a lot of this partly is neuromuscular, right? And they have that inability to do that, right? So super interesting. So strength coaches, I’d love to hear your thoughts on what we do on healthy people, but before we get to that, one question I have for you is this is oftentimes we say for example, not to say what’s the point, but to work on power, you have to have a baseline of strength, right?
Mike Reinold:
You have to have a baseline of strength to get a good power output, right? So if you’re weak, don’t go crazy working on power, right? And don’t misconstrue what I just said right there, but the concept is get a good base of strength before you work on power. Do we need to have that base of strength and that base of power before we start working on that speed of power development then. Is that a component you work in parallel or is that something that you think builds in that fashion? I don’t know who wants to tackle that question, Jonah maybe.
Jonah Mondloch:
Yeah, I can hop on that one. So a hundred percent, you’re right that you need a certain amount of force output before it’s worth working on rate of force development. Now if you look at power, all it really is a combination of force and velocity. So really power is going to be just an expression of your rate of force development. So you might have somebody who has high force output but low power and that’s probably somebody who has a lower rate of force development cause they’re not hitting that velocity component. So I do think before you start to train it is huge to make sure that you have good overall force production. And then from there can you produce force quickly is the next question, which you can see through power or through an actual rate of force development measure.
Mike Reinold:
I love that too. And sometimes you see on Instagram, you see people that are maybe a little early and you’re like, “man, they don’t look very strong, they don’t look very powerful.” And then someone’s working on how fast they can produce that power. Sometimes I’ve wondered, I’m like, “is that out of order a little bit,” but what do you think Dave?
Dave Tilley:
I just had a thought for Jonah. What’s the measurement of eccentric? What’s that deceleration one that we use, I forget the name off the top of head, but I feel like that one’s super important for what Lenny was talking about like braking force.
Jonah Mondloch:
Yeah so on a counter movement jump, we’ll look at eccentric deceleration rate of force development. So that’s when you’re throwing on the brakes during a counter movement jump. So at the very bottom as you’re loading, how quickly can you throw on the brakes? Which honestly leads into a really good point on all this is that the client or patient needs to know that speed is the component of the test. So if you do a counter movement jump and you just tell somebody to jump high, you probably don’t want to look at that eccentric rate of force development as a measure.
Jonah Mondloch:
They need to know that you want them to drop fast in their jump and then jump high for that to be a reliable measure. Same with the mid thigh pull. If you’re just telling them to pull as hard as they can, you’re not saying pull hard and fast, you’re not going to get good reliable outputs on the mid thigh pull, same on a knee extension. A client needs to know that speed is key, just like Lenny was talking about on his squats when he’s doing that with patients after an ACL.
Mike Reinold:
I think you added another variable there too Dave that, again, if you go out of order, you just wonder if you’re programming sub-optimally, but if you don’t have strength and you don’t have power, but then if you don’t have eccentric braking control, what’s the point on, I don’t know. I don’t want to say what’s the point. I mean that sounds misleading, but you know what I mean. If your focus is on rate of force development, but you can’t eccentrically brake the concentric movement to then produce force quickly, you’re focusing on the wrong things. You’re just doing the wrong things at the wrong time. So it’s not just strength and power, you could argue it’s even that eccentric control. That’s pretty good. All right, so what about our athletes? ‘Cause we haven’t really talked about that in terms of performance development. When do we start working on rate of force development with a healthy athlete trying to maximize their performance? Diwesh, what do you usually do?
Diwesh Poudyal:
So I would say that to a certain extent we work on it a little bit less or a little bit more on everyone. All right, So the younger athlete that’s not super strong yet doesn’t mean that we don’t work on anything that’s speed related or the speed component of that power equation. Like Jonah said, it’s again, just going to go back to what are they capable of doing and what do they need to maximize. So the older athlete that’s looking to chase a college scholarship, there we have a really good base of strength. There we have really good eccentric control. Well, we can probably focus on a ton of velocity work, including on our lifts. And then obviously from some of our jumping variations, making that a little bit more speed bias through some like assisted jumping or anything like that that can really start working the speed component of the power equation. But I would say that we work on some level of this with everyone, but maybe the older, stronger athletes just get a little bit more volume of it. Maybe they get a bit more advanced variations of it.
Mike Reinold:
And to give you credit for what you’re saying there, I think what you’re saying is that the people that have some, again, baseline strength and power, right? Can then start to work on making that more optimal. Right?
Diwesh Poudyal:
Exactly.
Mike Reinold:
And it’s interesting. So super interesting to do, how do we do this? I mean obviously, we have some of the technology, right? We have some of the velocity-based training equipment that you can use. We have some force platforms and dynamometers that measure strength because we value that. We think that was an important thing to invest in because we value that information and we value the biofeedback nature of it, right? But can you do this without that? Sure. I mean I think it… Like Jonah kind of alluded to it, just a lot of it goes into queuing with your exercise is easy. It’s like if you’re doing jumps with somebody, it’s not just about how high, maybe it’s about how high and how fast, right? For example.
Mike Reinold:
So there’s ways that you can probably do that without measuring, right? But if you have the technology and you have the devices that you can use to measure them even better, right? Awesome. So great question Bobby, appreciate that. Hopefully that’s a good help. I mean, this is a big topic obviously, right? So this is something that you can definitely look into a little bit more online. There’s tons of great resources and websites that talk about this stuff, but if you’re a physical therapist and you’re thinking about this, then you’re already in the right direction.
Mike Reinold:
I think that’s awesome because we wonder sometimes about these return to sport protocols and these return to sport outcomes that we’re seeing. I wonder if some of this isn’t necessarily that the person’s weak, but maybe they just don’t have the proper timing and force output like Lenny mentioned was really interesting. So anyway, appreciate it. Great question, Bobby. Head to mikereinold.com, click on that podcast link and you can keep asking us questions. And please, please head to Apple Podcast, Spotify rate review, subscribe. So you keep getting these episodes and we’ll keep answering them for you. Thanks again.
