Development of a biomechanical analysis process for use within a sports club

Biomechanical analysis is a typically time consuming process, often restricting its use in a professional sporting environment.

However, over the past three years I have developed methods to increase the speed at which an abundance of quality data can be exported, in a way that is both player and coach friendly. These methods are tailored around making biomechanics an accessible tool for coaches and medical to aid their work.

I present an outline of these methods to show how they may be used within a professional sports club.

The analysis is performed over four steps:

- Reflective markers are placed on the athlete

- Movements are captured using Vicon Nexus

- Movements are labelled in Vicon Nexus and exported to Visual 3D

- Variables of interest are calculated and exported as a report in Visual 3D

This process can be repeated periodically to adjust movement and technique, using quantitative data to confirm and support coaching points.

The reflective markers placed on the athlete will dictate which segments can be modelled and which variables can be analysed. The images below show a full body marker set up, allowing a multitude of variables to be analysed, and is good for whole body movements.

If a full body marker set up isn’t required however, a more focused marker set can be used, of just the lower extremities, or just the upper extremities for example. Which model is required, can be decided upon between the coach and the biomechanist. Less markers will require less time to prepare the athlete, so using the right marker set-up is crucial for saving time.

Once a marker model has been created, the trials can be recorded. By using a processing script (on the right), these trials can be automatically labelled and exported into V3D for analysis.

Once imported into Visual3D, a script can be performed to calculate whichever variables are of interest and export the data as a report. The script details the processes to be performed automatically, and if created properly, will output all the results of interest and export them as a easy to read report within seconds.

A multitude of variables can be examined, a list of which you can see below. The following images show how they can be used in practice, and how extra processes can be performed to ease their interpretation.

This image shows analysis of sprinting technique. The graphs display ankle, knee and hip angles in the plane sagittal plane, respectively. Also shown on the graphs are markers of when the left foot and right foot contact the ground.

These events can be used to identify the value of variables at a certain point in the movement. For example, the graphs on the right show the position of the foot compared to the pelvis. From these graphs we can see that when the foot contacts the ground, the foot is positioned in front of the pelvis, rather than underneath, as proper sprint technique dictates.

More complex variables such as joint moments can be examined if the lab has access to force platforms. The graphs shown beneath detail the right knee joint moments in all three planes. The Y and Z planes may display if a participant creates particularly high abduction and rotation moments which may be indicative of potential for ACL injury

Unlike conventional 2D analysis, joint angles can be looked at in three planes and the movement can be replayed as a skeletal model. Using events we can look at joint angles and segment positions at particular points of interest in the movement. This can be a good tool for analysing technique.

This can be a particularly good tool when teaching new technique such as the knuckleball free kick. We can look at the linearity of the movement as well as other key coaching points such as a deceleration of the shank, and position of knee over the ankle, upon contact.

The image below shows an example report, showing differences between jumping from a standing and walking start. The reports can also be programmed to highlight key points in the movements, and export metric data such as peak angles and velocities.

These reports can also be used to compare performance to an elite template. For example, through having separate lines on the graphs for the elite player and the youth player being tested (like shown below), you would be able to easily see how there techniques differed, and which areas needed to be altered.

This process, when set up correctly can take less than 2 minutes from movement capture to report output, and therefore could be done repeatedly to alter technique.

It can also be used to look at movement patterns, and longitudinally could be used to identify potentially injurious movements and characteristics.

It may also be used to monitor players movement patterns pre-injury (at the start of the season) and during the recovery phase post-injury. Ensuring that players are moving correctly before allowing back to play.

Thank you for reading

Joe [email protected]