Monday, January 2, 2017

Innovations in Movement - Blending Movement Science with Technology

Over the course of the last several years, we have talked a lot about movement and the correlation to injury risk and athletic performance. Based on these discussions, I think most would agree that assessing movement as a part of athletics is important.  But how do we do this in a meaningful and reliable fashion.  How do we do in a way that is valid and yet efficient enough that we can use it with a team of 18 volleyball players or 110 football players?  This is where we need to look at various technologies and then blend those with what we know from the movement sciences.  We will preface this series with the fact that I am not an IT specialist nor do I pretend to know all the ins/outs of technology.  However, I have used technology for >10 years to assess and treat movement dysfunction.  So although I am not an expert in this area, I have some proficiency with the use of in athletics and had exposure to everything that we will be discussing in this series.

Consider the above, in this series we are going to touch on several different aspects.

  1. Technologies to assess movement
  2. Technologies to treat movement
  3. Training technologies to train proper movement

During the course of this discussion, we will talk about various technologies, benefits of using and some of the challenges we experience with.  This is by no means a comprehensive list but is solely based on our experiences only.  So, lets begin by looking at technologies to assess movement.

Traditionally the ability to accurately assess movement was left to large expensive biomechanics labs.   Viacom systems (which is typically used in these labs) are the gold standard in movement assessment and in 3D movement capture.  However, Viacom systems are very expensive and require a lot of time to capture the data, interpret the data and to report it in a meaningful way that can be easily understood by the clinician and athlete.  In an efficient lab, it can take up to 3-4 hours for capturing the data on one player.  This does not include the additional 2-3 hours of data interpretation that must occur after for data reporting in a meaningful way to the consumer.  To be able to do that with an entire team of 18 players or 110, is just not feasible or cost effective.  All would agree this would provide extremely viable data we could use to develop more comprehensive programs, but in the end, the lack of efficiency and the cost make this an option for only a few.

The next level of interpretation would be the use of 3D systems.  One such system out there is the Myomotion system by Noraxon USA.   This system has all the bells and whistles and is truly a portable biomechanics lab.  This system has the ability to provide 3D motion, 2D video, EMG data and force plate data all at the same time.  This system uses 10-13 sensors that are attached to the athlete which then is Bluetoothed to the laptop that is capturing all the data.  


  1. Reliability - this system provides reliable and valid 3D data on the athlete in real time.  
  2. Data Analysis - there is no need for hours of data analysis to put this into a report.  All of the algorithms are run by the computer and this can be printed out instantaneously.  
  3. Portable - this system is portable so you can take this on the field, in the field house or in the athletic training room to do assessments.  
  4. Variability of movements - this system uses sensors to capture all the movements and does not rely on pre-programmed movements.  This allows the user to assess mechanics during a single leg squat and agility drills you create.
  1. Expense - this system is very expensive and runs ~>$25,000+ depending on the capabilities you are looking for.
  2. Data interpretation - although you get this in a report format, there is no interpretation of the data.  Unless you have experience looking at mass biomechanical data, interpreting what the data means and what you do about it is challenging and time consuming.
  3. Sensors - the sensors are cumbersome.  Since you have so many of them, putting them on takes ~20-30 min.  In addition, if you are doing true athletic testing where the athlete sweats, they move all over.  This makes the data that is captured unreliable.
  4. Time needed to test athlete - to perform a typical athletic assessment, this will take 40-60+ minutes per athlete.  This is considering that there is no dropping of the sensor signals and sensors don't move during testing and need re-positioning. 
Another 3D system on the market is DorsaVi USA.  This is an Australia company started by an Australian physiotherapist who saw the need for more reliable way to assess movement in patients and athletes.  DorsaVi uses an inertial measurement unit (IMU) with a magnetometer, gyrometer and accelerometer and provides lab quality data instantaneously.  These sensors capture motion, rotation and acceleration data within 3% of a Viacom system.  


  1. Reliability - this system provides reliable and valid 3D data on the athlete in real time.  
  2. Data Analysis & Reporting - there is no need for hours of data analysis to put this into a report.  All of the algorithms are run by the computer and this can be printed out instantaneously in a comprehensive report.  This provides valid interpretation of the data from which the clinician can easily interpret.
  3. Portable - this system is portable so you can take this on the field, in the field house or in the athletic training room to do assessments.  
  4. Efficiency - this system uses sensors to capture all the movements utilizing a pre-programmed sequence of movements.  This allows for efficient use with teams and requires ~15 min per athlete.
  5. Cost - this system is very well priced and is comparable to the cost of most 2D systems on the market.  
  1. Number of sensors - this system uses two sensors which helps in the efficiency but also limits capturing of movement associated with the pelvis during single limb movements.  Although this will be addressed with future upgrades, this a current limiting factor.
  2. Sensors - these can move and fall off during testing under athletic conditions.  DorsaVi has sleeves which help with this and aids in mitigating this challenge.
  3. Migration of accelerometer - with each rep, the accelerometer graph migrates upward.  Therefore this is reset with each rep but this adds an extra second to each rep.  Although this is one second, it is a variation from natural movement.
  4. Interference - this is really with any 3D system.  if there are strong magnetic fields close to where you are using the system (MRI), then this will create artifact and/or prevent capturing of data.
With the advent of gaming technology, there are several companies offering Xbox One related assessment tools.  Considering number of these companies coming out, this will focus on the use of the Xbox One for assessing human movement.  The Xbox One uses time of flight technology to assess human movement.  In most simplistic terms (and keeping in mind I am not a IT person), this type of system shoots light to the object being assessed and the amount of time that it takes for the reflection to bounce back to the sensor determines the distance from the camera.  From that, a 3D image can be obtained and movement captured.  


  1. Portable - this system is portable so you can take this on the field, in the field house or in the athletic training room to do assessments.  
  2. Efficiency - this system uses the camera (sensor) to capture all the movement so there is no sensor placement on the athlete at all.  Therefore this system is very efficient.
  3. Cost - this systems are very affordable (for the most part).  Although there is one system on the market for over $200,000, most are $1000 or less.  
  1. Reliability - the reliability of the data that is captured is questionable.  If you have ever played a game on one of these systems, we all have experienced where you swing an arm and the system did not capture the movement.  Same thing happens when you do this with human movement.
  2. Environmentally sensitive - these sensors are sensitive to environmental conditions.  If you are testing outside and it is hot, the system can overheat and burn out a sensor.  In one example we went through three sensors doing testing outdoors.  
  3. Light sensitive - these systems are also sensitive to light.  In outdoor very bright conditions it appears to interfere with the time of flight capabilities. 
  4. Artifact - these systems appear to have a lot of artifact in them.  This can be programmed out of the system to account for large variances but when this is done, the movement associated with that individual rep is a guess or based on algorithmic averages.  Most providers of this tech will not tell you this and you won't see it, but understand that is going on behind the scenes.
  5. Interpretation - most of these systems provide you with the data and require the evaluator to interpret the data.
Advances in 3D technology has come light years ahead in the last 4 years and we should see even more advances in the coming years.  Considering, this is a quick review of some of the current 3D technologies out there.  Next week, we will look at some of the 2D technologies out there.

Happy New Year to all.  Honored to have the opportunity to provide this blog and hope you find that what we provide in 2017 is better than 2016.

Dr. Nessler is a practicing physical therapist with over 17 years sports medicine clinical experience and a nationally recognized expert in the area of athletic movement assessment.  He is the developer of an athletic biomechanical analysis, is an author of a college textbook on this subject  and has performed >3000 athletic movement assessments.  He serves as the National Director of Sports Medicine Innovation for Select Medical, is Chairman of Medical Services for the International Obstacle Racing Federation and associate editor of the International Journal of Athletic Therapy and Training. 

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