I have two questions on the theoretical end of the spectrum, but I think we can get this to where we can talk about why strength training might be useful or interference. Good morning. Happy Munte. I have neuro coffee in hand and it is perfect. All right. Lots of things to do today. We're going to dig into a Q&A. It's going to be a combination of two questions. Try to make it useful. Some of this is going to be theoretical. So it might be interesting to some of you. And then the rest of you, you just turn it off. It's OK. I'm only expecting about five or six views on this one. So we're going to dig into some theoretical first. And this comes from Ryan. Ryan says, You said that the ability to expand and compress and expand again is a universal principle. Can you give a handful of examples in the human body outside of gait or shoulder and hip range motion? And also, can you name some examples in the natural world and the universe? I warned you. This is actually a fun question for me because I'd like to talk about some of this stuff. But Ryan, one of the things you have to recognize is that everything about you is a compression and expansion. So let's just look at your heart. And I think everybody has a representation in their head when they're looking at a heart beating. They understand that blood flows into the heart, it expands, it compresses, and then the blood flows out. And by the way, the heart doesn't pump it out. That's a different story. But everything inside of you is going to be based on compression expansion. So the peristalsis that moves the lunch through your gut is compression expansion. If we look at something local, like muscular contraction so if I concentrically oriented muscle there's actually a higher pressure within that muscle so the intramuscular pressure is higher as we reduce the concentric orientation we have a reduction in in pressure there as well so again we always have compression expansion taking place somewhere at some time. It all depends on where we're looking. We're also going to see this as global strategies. So every movement that you have is going to have some peak moment of force output, which will be representative of the compressive strategy to what degree is then dependent on what you're doing. You know, if you're drinking a glass of water, it's not going to be your maximum peak force that you could produce, but there is going to be a peak in that moment in time. If I'm doing a vertical job, it's a little bit easier to see that representation of that peak moment. So again, so every sporting movement is going to have this expansion to compression, to expansion representation.

If we're talking about a high jump, the moment that the high jumper plants his foot into the ground, there's going to be a peak resultant force, and then as he leaves the ground, he's going to re-expand. For a sprinter, it's the same thing upon hitting the ground: compression to expansion. If I'm throwing a baseball, there's a moment in time where everything squeezes tight. Time stops, and I produce this maximum output of force. It's just very, very brief, and so we don't see these things because our eyes can't stop time to recognize that. But we can measure these things with force plates and we can watch it on video. So Ryan, everything becomes this compression to expansion to compression. If we look at universal principles, we can get really theoretical here and say that spacetime has a very specific shape that looks like a light cone, because light behaves the same way, time behaves the same way, space, the influence of gravity, et cetera, all play into this sort of expansion, compression expansion. If you were theoretically near a black hole, you would probably recognize this shape as well. Again, this is all theoretical physics stuff, which is way above my pay grade, but it makes for a nice representation when we talk about our external rotation and internal rotation representations of how we move.

The byproduct of this though is I'm increasing compression which slows down time, so it increases the duration that I am in this internally rotated, force-producing position. So if by adding my ability to produce force requires that I increase the amount of time that I utilize that, I've now extended this period where I'm producing force, and I actually slowed down where I actually reduced my velocity where I needed velocity. I have now created interference. And so that's when force production can become detrimental. It just simply interferes with our ability to represent that one moment in time where I have this maximum peak force output that has to occur very briefly. So if I was a golfer and I extended the duration of the amount of force that I was trying to put out, I actually slowed down the club head because what I want is I want that peak to be recognized at a very, very brief moment in time that allows the highest possible force production. If I have to reduce the field of external rotation that I have available to me, which is representative of the amount of motion that I need to demonstrate ranges of motion or velocity, if I have to compress that to increase my force production, I have now again created an interference. So bilateral symmetrical exercises are well designed to increase my ability to produce a compressive strategy, which allows me to increase my peak forces at the right time. Hypertrophy is a byproduct of that. Hypertrophy by itself, again, to develop any significant amount of hypertrophy, there's going to be some compressive strategies associated, but it doesn't necessarily mean that it's interference. So again, the way that we figure this stuff out, Andrew, is that we train people. And so we actually have to do things and we determine what is the best course of action. And so we have to have some form of key performance indicator that is going to allow us to determine whether we're on the right path or not. So if I'm trying to improve someone's acceleration, so let's say that I'm measuring their acceleration through a 10 meter sprint from a standing start, I take them into the gym, I train them, I bring them back, and I retest that 10 meter sprint. And if that continues to improve, then my strategy in the weight room is good. And so if I'm using bilateral symmetrical activities to do that, great. But at some point in time, and maybe it happens and maybe it doesn't, at some point in time, it can become interference. The only way that you can tell whether this is going to happen is as you train them. And again, this is why we monitor key performance indicators.

So if I increase force production, if I reduce my external rotation field, but I don't need that range of motion to perform my activity, then again, I'm not creating interference. So all of these activities are great activities. We use them all the time. We have to buy bigger trap bars because we have people that can pull so much weight that we don't have enough room to put the weights on. And so again, these are not bad things. Bilateral symmetrical activities are very, very useful at certain times for certain people in certain circumstances. What you have to do is is you have to understand that this is always an N equals one experiment and we're talking about an individual here and then their response to training. So again, we've always got the expansion, compression expansion on the table as a representation of movement. We superimpose force production on top of that to determine what is going to be the best course of action under a specific context.

Most of the instabilities that we see from an ankle perspective, we're just going to use that as our example, tends to be subjective where they say, hey, it feels like it's going to give way in this position. Very rarely are we capable even separating out proprioceptive or somatosensory elements from the motor output. It is the same system. We're not going to really separate those. But clinically speaking, we're not going to be able to follow some of the guidelines that you'll see in some of the research where they actually use apparatus to determine whether we have an input problem or an output problem. It's going to be both under all circumstances. If you need a test of any kind, if you work in those clinical situations where you need a test, the Star Excursion Balance Test has some research behind it and has a little bit of crossover between some of the appropriate sub-development and the motor output element. If they are actually capable of separating those, there's some hop tests that might be useful as tests and retests again if you have to use those kind of things. Again, those are your comparisons. Now, let's talk about what we're dealing with, though, under these unstable ankle situations. Under most circumstances, we're actually dealing with an early propulsive representation of a foot. The way we know this is if you look at some of the research and they talk about the anticipatory position so that if somebody jumped off of a box and they demonstrate this anticipatory representation where the foot is actually landing or positioned towards an inverted position. So this would be our ER representation of the foot. And again, because we're going to be toes down, it's going to be our early representation. So we're actually looking at here is a foot that kind of looks like that. So I have the ER tibia. I have a foot that's biased towards ER or supination. Also in these same research studies, you're going to see a reduction in the amount of knee flexion on landing, and you'll see a loss of hip ER under many of these circumstances. And so what we're actually looking at is we have a foot that cannot internally rotate. So we're sort of stuck at the end of heel rocker. We want to have an ankle rocker under normal circumstances, but we have a foot that can't really do that. We still have to get force into the ground. So if the tibia is biased towards ER, that's going to keep me extended, but I need my internal rotation. So where am I going to get my internal rotation from? So then we have to grab our pelvis and we have to say, okay, well, I can't do it through the ankle. I can't do it through the knee. So what am I going to do?

So what I'm going to do is anteriorly orient my pelvis to get internal rotation and force into the ground. This helps drive the medial aspect of the ground to protect against another inversion sprain, but it results in a loss of external rotation. We must look at this systemically; it's not just an ankle problem. From a strategy, we will try to restore capabilities for middle propulsion. We also must impose rate and variability, because we move quickly through space. If we don't address these, we may not get the input information needed for protection at higher speeds. If you step on a pebble and quickly invert, you're more likely to resprain the ankle. For programming, since we're dealing with foot, knee, and hip positions, we'll first reduce that anterior orientation. An easy way is to place the foot on the wall in supine to capture foot and pelvic cues and reorient. This statically recaptures the pelvic position. Progressively, we'll stand the person up and do a cross-connect in an upright position for ground-up cues. This transitions into dynamic activity, like a single leg RDL with a landmine. Eventually, this becomes very dynamic or explosive, reinforcing yielding capabilities at higher speeds and teaching tissues to absorb and release energy. We'll use this process throughout the program. Next, we must translate the tibia over the foot to go through middle propulsion. We'll use split stance activities. Initially, we'll use a front foot elevation to reduce load on the affected side, allowing more effective tibial translation and capturing true internal rotation at the hip. This keeps the medial calcaneus and first metatarsal head on the ground to prevent external rotation and inversion sprains. From there, we progress the load by elevating the rear foot, still translating the tibia forward. Then we superimpose variability and rate using oscillatory impulses in that split stance to dynamically and explosively capture foot cues while maintaining internal rotation. We then play with directions, expanding the challenge by moving towards internal and external rotation while keeping those foot cues. This could include sled drags, more lateral lunge or split squat patterns, and cutting drills. We can also use elevation, like dynamic step-ups onto boxes to reduce ground contact forces, then build in change of direction. Eventually, we work on normal agility. We must adapt these for the individual; not everyone will need high-speed change of direction work like athletes.

Initially we're probably going to want to use a front foot elevated situation which is going to reduce the load on that affected side and allow us to translate that tibia a little bit more effectively, capture the true internal rotation through the hip that's going to allow us to keep the medial calcaneus in the ground and that first metatarsal head to prevent the ER-ing and that's going to result in our inversion sprains. From there we just progress loading and so what we can do is we can tip your backside up so we put a rear foot elevated here and again we've just increased the load but we're still translating that tibia forward and now we start to think about okay what else can I superimpose? I need some variability and I need some rate. And so here we might use some oscillatory impulses in that split stance to help us capture these foot cues dynamically and explosively and still hold on to our internal rotation. So again, we want to think about imposing these other elements of force as we progress through the program. Then we start to play with it with directions. So what we want to do is expand the challenge of moving towards internal and external rotation and again hanging on to those foot cues. First metatarsal head on the ground, medial calcaneus. So this could be something like a sled drag or we start to move our lunge patterns or split squat patterns more laterally. And then we start to work on maybe some cutting drills. We can use elevation. So we use our dynamic step ups onto boxes to reduce some of the ground contact forces. But then we can build in change of direction there. And eventually you just get somebody down on the ground and you work normal agility. Now, keep this in mind that we have to adapt these things for the humans. So not everybody's going to be doing the dynamic box work. Not everybody's going to need to work on their high speed change of direction like we would for some athletes. So let's adapt this program to those individuals.

I am. Thank you for asking. Thanks for doing all these Q and A's. You're welcome. He says, I've got a wide ISA client who presents with limited shoulder internal rotation on both sides, more on the right. He also has limited shoulder flexion but more on the left. So it's more limitation on the left. Any experiences right shoulder pain when bench pressing. His right elbow likes to tuck in more. All his hip measurements are limited as well. We love your thoughts and solutions on this. Okay Ben, you didn't give me a whole lot to work with but you gave me some really, really good clues that I think we've got enough information to help you out. So let's dig into this. First and foremost, let's describe what's actually going on while he's bench pressing. So you're talking about a position where the left arm seems to be away from his body and his right arm seems to be tucked in. And so what that representation actually is, is his ribcage and thorax are actually turning to the right. So when you have your hands fixed on a bar, that's going to secure the hands in pronation, which is going to put us towards internal rotation, which is where we got to be anyway for a bench press. But point being, if I've got limited shoulder flexion, the typical compensatory strategy for limited shoulder flexion, especially in the early range of shoulder flexion, which you would be exposed to in a bench press, is to turn away from it. So again, so he's actually turning his rib cage on the bench. And so this arm looks like it's far away, and this one looks like it's tucked in. Now, here's the problem with that. is because what you've actually done is you've actually turned the right shoulder towards greater internal rotation. So I need internal rotation for bench press. I need internal rotation for my compressive strategy, constant regrain rotation and propulsive activities, and then I need to move through a space that demands I have internal rotation. So we got a triple whammy there and so you got a ton of compression in that right shoulder under these circumstances. And so that may be why your client is experiencing right shoulder pain. This is actually a really cool little little competitor strategy and it's probably not that uncommon So, probably what I'll do, as soon as I get a little bit of time, Ben, I'm gonna go into the gym, I'll probably grab Eric and we'll go through how this is actually happening. So, if I don't do that soon, please send me a reminder. All right. So what's our solution here? Step number one, because you're dealing with a painful situation, you're going to have to clear this client for any structural issues. And so if you don't have the capacity to do that, I suggest you get them to somebody that can.

Let's rule out anything that may be important under these circumstances because whenever we're dealing with pain we've got to clear those structural issues. Number two, take a break from bench press. You basically got two options here. Either take the bench press away because it is problematic or you keep training the heck out of it as hard as you possibly can until it breaks and then you have to take a break from the bench press. Either way you're going to have to take a break. I suggest you do the first option there, much safer and much more caring for that client. In fact, what I would do then is I would remove all barbell exercises from his program at this point. You're basically fixing the extremities under any circumstance, whether we're talking about a squat, a deadlift, a row, or any kind of pressing, you're fixing the extremities in a position that are going to promote more internal rotation. From a rehab standpoint, again, if you don't do manual therapies yourself, you're probably going to want to find somebody that does. If this person has any level of hypertrophy or is actually a very, very strong human being, you're probably going to need some help getting this rib cage to move. So you got to get a dynamic, infrasternal angle. So that might require some manual therapy. We need sternal movement because if you're missing internal rotation, you don't have pump handle movement in the anterior thorax, so we need to recapture that. Clavicles are going to be limited in the ability to rotate. When you've got to get the ribs to move more effectively, you're going to have to decompress the scapula from the dorsal rostral space. So that's a manual technique, by the way. I have a video of that on YouTube. I also have one for the scapular elevation. So look at those two. And again, if you don't do manual therapies, get somebody that can apply those techniques. You may have to assist that that's good with their hands to help reduce some of the concentric orientation as well. Basically, you've got a guy that's really, really compressed and you're going to get a whole bunch of expansion here to restore his ability to move freely through space.

which is going to help start to reshape the thorax a little bit, get some of that anterior posterior expansion, and as you can move into a lower obliques type of an activity, which would be closer to what looks like a side plank variation, you'll start to get some pump handle activity from that. You can do supine cross-connect so they should be in a non-provocative position based on the upper extremity and then a sideline propulsive activity will also be helpful. Again, sidelines are a great way, especially for these wide people, to get some of that anterior posterior expansion because we're taking advantage of gravity. Once you can capture 90 degrees of shoulder reflection without pain, supine arm bars are now on the table. You can throw in a screwdriver on top of that to promote some internalized zone rotation and then you can eventually move to a prom propulsive activity, which is going to get you a ton of that posterior expansion and yielding strategy that your client is lacking. If you want to take you into the gym, we've got suitcase carries that are probably on the table right now. Eventually you can probably turn it into a rat carry so we can get some E.R. and I.R. out of that. Backward sled drags with two handles to promote the uniling strategy posteriorly so you get some expansion, you get some pump handle action. You're also going to get some hip mobility out of that as well. High rep tricep push downs with a band. Also it's going to keep you close to that transition between internal and external rotation and give you some of the yielding strategy posteriorly in that dorsal rostral space. Again, you're going to need that. So dumbbell curl variations. There's a bunch of videos on my YouTube channel for that that you can also use to help keep that dorsal rostral space expanded. The key element with any of the resistive activities that I've just mentioned is that you can breathe through it. The minute you have a breath holding strategy under any circumstance during these activities, you are promoting the limitation that you are trying to alleviate. So keep that in mind. So in a nutshell, what you guys, you guys, it's very, very compressed. They're using compensatory strategies during the activities in question. So in the bench press, maybe they're carrying them around, I don't know, but either way, when they're bench pressing, this is what they're using. So you have to reduce the compressive strategies and eliminate the interference through all of the activities that you're doing. So you might have to restructure some programming. Unilateral activities are going to be much more effective than bilateral symmetrical activities and take the barbell out of their hands.

If it doesn't, if you need more, go to askbillhartman at gmail.com and we will provide you another solution if you have another question. Everybody have a great Wednesday and I will see you. Oh, coaches, come to the Coffee and Coaches Conference Call tomorrow morning, 6 a.m. It's gonna be Thursday. It's Chips and Salsa Day tomorrow. Have a great day. Good morning. Happy Thursday. I have neuro coffee in hand and it is perfect. And I must say it's exceptional. The basic rules, the basic rules. You have to have ER to express motion. And then I need IR into the ground to produce the force. You will find a way to IR. It just doesn't necessarily make it terribly efficient every time. And if it alters especially with a high velocity, so arm speed on a professional baseball pitcher is somewhere between 7,000 and 9,000 degrees per second, okay? So to give you an idea of how fast that is, take your arm and swing it in a circle as fast as you can, and then do that 20 times in a second. That's how fast the arm is moving when they're throwing a baseball.

So Bill, real quick, just to summarize from my understanding for not only athletes, but if you're in general trying to increase force production for whether it be like golf or shot put or anything, the idea is you would like to create more external rotation for the ability to create force. However, if you don't have that capacity, you're not going to be able to.

Okay. External rotation came first. Embryologically speaking, it comes first. Evolutionarily speaking, it comes first. Internal rotation is force production into the ground. So back when you were a swimmer, you didn't need to produce force into the ground. External rotation provides you a space to move and to demonstrate velocity. You can't move quickly in internal rotation. It's not designed for it. External rotation, very, very fast. So for me to express force, I have to have enough external rotation to access the position of internal rotation. So ER comes first. I have to have a place to go. Then I have to be able to move into that place. And that's where I can superimpose the internal rotation on top of it. So do you work with golfers, Jordan?

No, I just for some reason golf came into mind as rotation loading.

Any kind of turning sport is going to be very, very similar in regards to the rules. So when the golfer takes the club into the top of a backswing, he is moving towards a position of external rotation. So he has to create a position of external rotation. So it's a space where he can access the shape of his body and external rotation. And then he turns into it. So the hip and the pelvis are oriented such that I have this whatever the maximum amount of external rotation that I have. And then the pelvis will turn towards that and that's the internal rotation. So both are always happening at the same time. That's why you hear me use the word bias because that tells me I have more of one than the other, okay? And so you have to have the extra rotation to be able to access the positions that you produce the most force in. If I narrow the extra rotation space, I've reduced my potential for internal rotation efficiency. Efficiency, doesn't mean I can't produce it. I'm just gonna find another way to do it. So what some people do when they don't have enough ER, which means that they narrow their IR, they dump their pelvis forward and that pushes into the ground. Perfect, there's my internal rotation. Because ultimately what internal rotation is, is a downward force. We just happened to create it by turning inward. Okay. So again, you just think about, think about the first amphibian that came out of the water and decided to walk on land. He's used to swimming like this, right? And then he gets up on land and there's gravity to deal with. And now he has to go, instead of going like this, he's got to go like that. He's got to turn in and push, right? Totally different. You know, if somebody's just a performance related, issue, right? It's not a pain related issue. It's not an injury kind of a thing. It's like, you just have to really well define what you want that outcome to be. Like what measure are you going to be chasing? And then you just, again, it's just a stepwise process. It's like every two weeks you're following a key performance indicator and you're going, okay, did this change? Yes. Okay. What was our, what was our test that we're using to tell us that we were on the right track in the first place? That's the process. It's not like you're gonna write this magical 12-week program and you're gonna go, everything's gonna be great by the end of 12 weeks. It's like, anybody ever written one of those? Never? Yeah, me either. No, I have, I mean. Well, you try, like you project. So there's nothing wrong with projecting outward, but if you're not following some sort of indicator that tells you that you're on track, it's like, you just wasted 12 weeks.

If you get to the end of 12 weeks and it didn't happen, guess what? Wrong program. And now what they do, and the reason that you have, like this is what I mean, I don't know, this is like an iPhone 4 or something like that, but there's like a gazillion iPhones now. It's like they just slowly reintroduce new technologies, right? And so, they create this minimum viable product of whatever it is that they're trying to develop, and then they just slowly improve it over time. That's what training is. So what we need to do is we need to write programs the same way that they write software. It's like, okay, how much improvement can you make in two weeks that accomplishes the goal? Did it work? Cool. Okay, we'll keep going in that direction. And then we see improvement. And then at some point in time, you're going to hit an impasse where it's not going to change. It's like, okay, there's where you make the next tweak in the program. So it's like this continuous improvement over time versus trying to project out, which you can't do for any human being on the planet. You can't project anything 12 weeks out. You have no idea.

Wait, I'm thinking too far ahead. I love that. Thank you. That's actually super helpful.

Yeah. But that's how you write a program. It's like the way that I write a program is like I have this general idea of where I wanna go and then I can only deal with the acute, right? Because I have no idea what the response is gonna be. So what if somebody has like a crappy night of sleep, they miss four meals, they had a fight with their significant other and then they come into the gym and it's a crappy day. And I had the hardest day of the month planned and they don't have the resources for it. It's like, I can't predict that. I can't predict that. So again, we're constantly adapting to the intention and the desired outcome and then the potential changes that are available to us. What resources do I have? Periodization manual. and you read the programs in there, those weren't pre-written programs. Those were executed programs that were successful. It doesn't mean that that's how you program, okay? It's just a representation of a program. Does that make sense? Everybody get that? Give me a thumbs up, yes?

So it's like the archetype of a standard Russian program essentially.

No, it's like, here's what we did over time and this is what worked. It's like you're seeing the historical information. It didn't actually exist. They wrote down what they did. They didn't plan the program and then execute it. They just said, what are you doing today? Okay, I'm going to write that down. And then they printed it and everybody goes, oh, this is what a program looks like. And so then they literally duplicate that program and they go, I don't know, we didn't get a very good outcome. When the reality is they weren't guided by principles. They were trying to follow the cookbook. But you're seeing historical information. It doesn't matter what you want to take away from that stuff is what guiding principles did they use to execute this, right? Rather than this is how you program. Because if I wrote a programming book, it would be a very short book. It would probably have like three statements. It would be like, what do you want to do? Do something. Did you do that? There you go.

is that the contralateral arm, so if we're looking at the left foot at max propulsion, the right arm is going to be pointing straight down towards the ground. This is important when we're talking about this contralateral versus ipsilateral influence. Because if we go to a suitcase carry and we start to look at how a suitcase carry works, what that suitcase carry is doing is it's actually holding the arm down at this max propulsion moment in regards to what the upper extremities are doing during walking. So now we have to say, 'What is this ipsilateral load or contralateral load depending on which foot we're looking at really influence this?' So if we're looking at the left foot with a right suitcase carry, we've got a right arm that's going to be held down in its max propulsive moment. And so what we're going to do is then we're going to actually enhance the contralateral max propulsion moment in the foot. And so what we're going to see is we're going to see an increase in the loading during max propulsion. And so we're going to have a very, very strong IR internal rotation force into the ground with the left foot with this right suitcase carry. So if you watch the video here you'll actually kind of see that there's a little bit of a limp that would be associated with this ipsilateral carry. This is obviously can be magnified; like the heavier the weight that you carry, you're going to see a much more bigger compensatory strategy here, but the thing that once you recognize is that this ipsilateral load does change things. So now if we look at this from an ipsilateral standpoint, and so I'm carrying the weight in the right arm, what I should see then is a reduction in this medial heel contact that we would associate with our max propulsive phase. And that's exactly what happens. And so what we have now is we have the right suitcase carry on the right side, inducing a lightening of this max propulsive force during the right foot contact. So this ER actually reduces the max pronation moment. This maintains extra rotation through the gate cycle. And so what we end up with is an enhancement of the posterior overcoming action on the right side with the right suitcase carry. Now, let's take this concept and let's move it to the split squat because we're going to see the exact same thing in the split squat. So if we look at this from a contralateral perspective, I've got weight in the right hand and what this is going to do is it's going to induce a little bit more of the internal rotation on the contralateral side. So my left leg lead is now going to be able to internally rotate easier. If we looked at this from the ipsilateral perspective, then so now I'm going to have a right foot forward split squat with a right side load. What I'm going to see is I'm going to see again the inducement of a little bit more of an ER bias. It's going to enhance my ability to create the overcoming action coming up out of the split squat. So again, all we have to do is we have to look at the concepts of normal walking and then how does this ipsilateral versus contralateral load influence. And so again, if we're looking at the contralateral, we're going to enhance our ability to produce either max pronation or internal rotation. And if we're looking at it from an ipsilateral standpoint, we're going to enhance the ability to ER or reduce that max propulsive phase as we're walking.

If we looked at this from the ipsilateral perspective then, so now I'm going to have a right foot forward split squat with a right side load. What I'm going to see is I'm going to see again the inducement of a little bit more of an ER bias. It's going to enhance my ability to create the overcoming action coming up out of the split squat. So again, all we have to do is we have to look at the concepts of normal walking and then how does this ipsilateral versus contralateral load influence. And so again, if we're looking at the contralateral, we're going to enhance our ability to produce either max P or internal rotation. And if we're looking at it from an ipsilateral standpoint, we're gonna enhance the ability to ER or reduce that max propulsive phase as we're walking. So Dan, I hope that helps a little bit. If you have any other questions, please send them to askbillhartmanatgmail.com, askbillhartmanatgmail.com, and I'll see you guys next week.