I want to thank Michael and Brett. I had no idea what Scott's presentation would be, but you'll see in a minute that his presentation really leads well into my presentation. I'm going to talk to you right now about motion capture in sports. I want to say I have two disclosures. I'm a paid advisor for Major League Baseball, and I'm also a paid advisor for Dari Motion, which is one of the motion capture companies. Now why do we do motion capture in sports? Really two reasons. One is to maximize the performance, whether how fast you throw or run or whatever. But as a sports medicine group, we're probably more interested in the second reason, which is really to minimize the stress, the forces, the torques, and hopefully minimize the risk of injury. Motion capture in sports, really before 1970, motion capture in sports really wasn't captured. It was just the coach, who was usually a former player, would watch the athletes and then give feedback to them. But in the 1970s, technology came out, which was high-speed film. You see this camera with high-speed film. I saw some of these. They were really noisy. The film spun around, and you collected it, and then you could bring it back to the lab and digitize it over here, meaning get the film developed, bring it back, throw it up on a screen, and you say, here's the elbow, here's the shoulder, etc., and then you could get the stick figure. This was right before I got into this, and this was not good because you'd make the film, and then the next day you see you recorded it, it was too dark, or you didn't do it right. But a real big breakthrough happened in the 80s when we switched from film to video, because you could make the video, and then you could see a minute later whether you got a good thing or whether you have to do it again. This is actually what's called a NAC system. It was the first system I used in the 80s at the Olympic Training Center, high-speed video, and you could, again, capture the data and see it right away. The other breakthrough that happened in the 1980s is that the math got better, and they did what's called direct linear transformation, meaning you could... We're all three-dimensional people, but cameras just see one viewpoint, and so the math arrived where we could have multiple cameras and get a three-dimensional description of our motion, which was really a breakthrough. But it was still manual digitizing. You make the video, and you go, here's the elbow, here's the shoulder. Then the company started coming out with automatic digitizing. You can see my lab in the 1980s. We put these big silver dots on the person, and the computer and the video can track and get the three-dimensional motion. That was what we used. Then in the 1990s, we were just doing our business with biomechanics and buying this expensive equipment that was so-so, but the movie industries and entertainment, they started pumping a lot of money into the technology, and we as biomechanists and scientists got better equipment because Hollywood was pumping a lot of money into making better motion capture. That's the background, but where are we today? That's really what we're talking about. Where is motion capture today and in the future? It's really a revolution, what's happening now. That's not hyperbole. I'm going to show you in a second. This is really what's happening. The technology is amazing, what's happening now. The other thing that's important is not just that the technology is advancing, but people want it. The athletes, the teams, they grew up with technology, and they want it as a competitive advantage. There's a real desire for it and the technology, and I'm going to show you that it really is a revolution. I'm going to talk about something that I know well about, which is baseball. This is how many scientific publications there have been in baseball biomechanics over the years. Since we started at ASMI in the 80s, you can see it went from about one or two a year to about 40 a year. That's pretty good. There was the science of biomechanics of baseball. Look what's happened in the last 20 years. It's not been 20 or 30 publications per year. It's more like 160 or 180 scientific studies per year. This is happening, biomechanics in sports. Like I said, I'm at ASMI, but because in baseball in particular, there's so much biomechanics, we formed the American Baseball Biomechanics Society last year. This is a society very specific for baseball to provide valuable information about biomechanics to players and coaches and teams, and also to set the standards. Just in the last year or so, that's the website. You can join it if you want. You don't have to be a biomechanist. We have some team doctors who are members, but we have 240 people. We have corporate sponsors. A lot of those companies are the motion capture companies that we were talking about today. Anyway, motion capture today, still the gold standard is the optical motion capture system. Here's a picture of our lab in Birmingham about three hours from here. You see the little silver dots on the person and capturing the motion capture. What's happened though recently is it's not limited to the lab anymore. You could take the lab out to the field, and the cameras, essentially the sunlight doesn't mess up the cameras anymore, and you could see the reflection of the reflective markers as you see here. The other thing that's happening is the optical motion capture. Again, here's a picture of kind of a naked guy in my lab with his tight pants and little silver dots on his shoulder and elbow. This is still the gold standard, but now there's markerless. You could see if he's pitching here. You could just get rid of the markers, put his clothes on, and capture full body motion capture. You see his stick figure, and he doesn't have any markers on his body. The other thing that markerless motion capture is allowing us to do is most of the sports games I watch, people aren't wearing silver little dots on their body. We can now capture three-dimensional biomechanical data from in competition. That's really been a breakthrough. There are full systems, multi-camera systems in some stadiums and ballparks. You may have heard about some of this stuff. I want to talk about this. There are a lot of biomechanics systems where people have a cell phone, and they say, our system, you could just do this, and it gets the full three-dimensional motion. I want to talk a little about that, about what it does and doesn't do in a second. I also want to talk about inertial measurement units. This is the only part that really overlaps with Scott's here, because this is a wearable sensor, IMU, inertial measurement unit. The big one in baseball is this modus sleeve, which Scott put up that name, but also there is full-body systems like Xsense where you have these IMUs, these sensors on your body. Then there's electromagnetic just for completion, which is these sensors are actually putting out an electromagnetic active signal, but honestly, this one isn't as popular right now. It kind of lost the battle of technologies. I want to point out a few take-home messages here. One of them is that the camera systems, they are measuring position. They are taking pictures of the athletes at different times. They measure position and angles directly, and then velocities and accelerations, they'll report it, but keep in mind they don't measure it directly. They're seeing how fast the position changes by taking the derivative in the math, but it's pretty good calculation, and they certainly don't measure forces directly. They do some math, force equals mass times acceleration, and make some calculations based upon the positions. These IMUs, these wearable sensors, they don't measure position. They measure motion, like in your cell phone, when you jiggle it, it's measuring angular velocities and linear accelerations, and then they do mathematical integration to get positions, and again, forces are indirectly calculated, so just keep in mind that that's what those things do. I want to leave you with some insights I have, hopefully, to share with you. When you're considering as a sports medicine physician or other, whether you're a clinic or your team is going to buy a motion capture system, consider what kind of digitization. Is it a manual or automatic? Does someone have to process the data or not? Consider if it's two-dimensional or three-dimensional, and in the year 2021, I would hope you're getting three-dimensional. Consider the capture rate. Honestly, if it's at your clinic and you want to study your patients sitting and stepping out of chairs, maybe 30 hertz is good enough, but if you're going to get people running and flipping and things like that, you need the faster frames capture rate. You have to consider the accuracy of these systems as well. What do these systems tell you? They tell you the kinematics or the motions. They also tell you the forces or the kinetics. And then, kind of piggybacking on the last presentation, we get some data and we're trying to make something of it, and honestly, some of these systems give you so much data. Every pitch of every game or every run in is just an overload amount of data, so you need to figure out who's going to collect this stuff, and that might be, you might have to hire a biomechanist for some kind of equipment, and some others, you might have a video guy or gal, or a clinician, a physical therapist, trainer, it depends what kind of system, and then once you get it, who's going to interpret it or use it? Do you have to have a biomechanist, or can a clinician, a physician interpret it, or a coach or an athlete? So here's the last table I'm leaving you with here. Let's compare these systems. The multi-camera system with the markers, multi-camera system without the markers, the single camera kind of like the cell phone thing, the IMU wearable ones and the electromagnetic, the multi-camera systems are more expensive. You have to buy more cameras, higher speed, the computer has to be smarter, they're more expensive. The single camera is pretty cheap, it's usually your cell phone or maybe you buy some software. The IMUs are pretty cheap as well. Some of these systems, you had to buy the equipment and or you have to pay an annual or a monthly fee, so that's how some of them are operating where you have upfront costs but then you're paying per month because they're storing all the data on the cloud, so you have to consider the cost there. The accuracy, I'm telling you, the last 20 years or so, these cameras with the reflective markers, they are good, they're very accurate, they're essentially the gold standard. There's a lot of controversy and a lot of work being done at our place and others about how accurate or not the multi-camera systems are without the markers. I hope they're really accurate and honestly, so far, I'm pretty pleased. They still need some more proof but they seem to be pretty good. The single camera, it's a little more promise than delivery right now and so if you are going to get a single camera system, that really should consider, that's not going to tell you someone bent their knee 37 degrees or something like that. That's going to say something like they leaned to the left or they bent their left knee more than their right knee. It's really not accurate enough at this point but that will be good when it gets there and also the wearable sensors, sometimes they're pretty good but they still need some more work. Mobility, the single camera system, you're good to go. The inertial measurement unit, good to go but the multi-camera systems, it's more of a process. As far as who could collect the data and use it, again, the multi-camera marker systems, you really need a biomechanist to get the medial epicondyle and the different bony landmarks you need to put it on. As you can see, things get easier. The single camera ones are easier. Even an orthopedic surgeon could do it, a doctor could do it, a coach could do it, anyone. There's a trade-off there and I think I'm out of time and thank you for your time.

motion capture

sports

performance

injury prevention

advancements