Changing the game – how inertial motion capture sensors (IMUs) are improving sports performance analysis and athlete recovery

Motion capture is well-established as an essential tool, not only for biomechanics research, but also for sports injury rehabilitation, training and sports performance at all levels. Indeed, the importance of motion capture and other tracking systems to sports science is confirmed by the growing numbers of associations and governing bodies seeking to standardise and classify the various sports performance analysis technologies available to players, coaches and teams.

For example, earlier this year, FIFA, one of the world’s most powerful governing bodies in sport, announced a new global standard for Electronic Performance and Tracking Systems (EPTS). As part of its Quality Programme, the new FIFA standard not only sets the highest bar possible for technology vendors, it also helps club and national teams navigate the sports performance analysis market, giving guidance to users on best practice in data capture, output and use.

This is a major milestone. For such a sports body to take this step truly underlines the importance of technology in maximising athletes’ performance, minimising risk of injury and optimising return to play.

The science doesn’t stand still, however. The question is very much what comes next.

The rise of inertial data

Although FIFA has taken a lead on this issue, the fact is the need to understand sports performance analysis and improve tailored care for athletes is a major priority for every sport. It’s why we’re seeing motion capture used more and more widely for athlete recovery and in the world of sports performance. The use of wearable technology such as IMUs (which we’ll explain later) spans almost all sports – from football to swimming, tennis to golf, athletics to basketball, as well as baseball, cricket, long jump, and weightlifting.

This increasing adoption also comes at a time when the research and development of motion capture technology for performance analysis is accelerating. Traditionally, motion capture has meant ‘optical’ camera-based systems – with markers used on the body to track the position and motion of joints and limbs. Now, with the enhanced specification and miniaturisation of sensors, as well as lower costs, the sports performance analysis field is seeing the rise of ‘inertial’ motion capture technology (also called Inertial Measurement Units or IMUs).

As opposed to athlete GPS systems, IMUs use accelerometers to capture more data on joint impacts, limb movement and limb loads. With more lightweight, easy-to-use, flexible, and reliable wearable IMU sensors hitting the market each day, it is possible to access new insights and analysis into athlete performance and athlete recovery.

Indeed, the capabilities of some of the high-end devices are remarkable. Of particular interest is the breakthrough in exceeding previous IMU accelerometer threshold limits – enabling field-based inertial measurement of impacts and loads up to 200g. By capturing the highest speed and highest impact sporting movements, researchers and coaches are able to quantify and gain a better understanding of key movements such as cutting, deceleration, landing, and sprinting with the latest generation of IMUs – assisting sports performance analysis and athlete recovery. Of particular note is that, unlike athlete GPS systems, these inertial sensors are able to measure the forces on the limbs.

The power of integration

Reducing guesswork and risk, the availability of more data is enabling the sector to set clearer goals and create uniquely personalised training regimes for athletes.

However, while optical and inertial capture technologies can be used as standalone systems for focussed applications, the future lies in how combined inertial and optical motion capture will help deepen our understanding of the performance assessment and rehabilitation of athletes.

By fusing optical and inertial technologies – echoing the relationship with Vicon and IMeasureU – it is possible to make the whole greater than the sum of its parts and reap huge analytic benefits. While optical technology has traditionally been limited to the lab, inertial technology takes motion capture technology out to the field. Take our latest IMU, Blue Trident, with its inertial data athlete performance can be analysed in real-time during a training session in tandem with Capture.U, our app-based solution. Plus, we’ve seen our customers integrating the most accurate, real-life data from “in the wild” into the lab for further study to bring a new depth to their biomechanics research.

Alternatively, it is possible to capture both inertial and optical data simultaneously in the lab. This gives analysts and coaches the most comprehensive picture. However, the real prize is for users who combine Vicon’s optical and Blue Trident inertial technologies in the field – and this is where we are seeing some of the most exciting research today.

The integration of the live inertial data feeds from Blue Trident with video outputs from the camera systems is potentially a game changer for those working with athletes in the field. While the numbers are important for sports scientists, for the athlete and the coach having the immediacy of the data alongside the video feed can be incredibly powerful in tailoring training sessions and honing techniques.

Of course, at the heart of these developments is increasing the ability of coaches and athletes to have rapid access to tracking results. This is particularly the case in high-performance rehabilitation settings. Being able to relate data to performance and symptoms, allowing confirmation or modification of subsequent load, will give coaches far more control to optimise every training session.

Real-time feedback must become the new normal as human-sensor technology continues to evolve. As such, the combination of optical and inertial technologies will contribute to the performance improvement of athletes and increase their availability for games – ultimately improving teams’ sporting and commercial performance.

Making data work for athletes

Although we are still in the early days of understanding how these two motion capture technologies will work together, progress is likely to be rapid. There is an increasing demand on footballers to push the limits of performance and remain injury-free and, as such, there is a huge incentive to have better data with which to make assessments and plan training regimens. And so too, when it comes to running gait analysis, there is huge potential to positively impact and speed athlete recovery with data obtained from IMUs.

However, for all the technological development, we cannot lose sight of the most important people in this equation – the athletes. While researchers are looking for more and more data to deepen their understanding of human movement, we must ensure that this data and the technology delivers benefits to the athletes – particularly when it comes to rehabilitation and athlete recovery.

The athletes themselves – who, after all, are doing all the hard work – must have confidence that they are making progress and that their sessions and drills are being performed at the right rate to aid a good recovery, or further improve their performance. It is crucial that we get buy-in from the player themselves, their coach, and physiotherapist. Looking at running alone, this is truly one of the disciplines most effective by mental attitude, so it’s important not to underestimate the role of the athlete in ensuring a running gait analysis is fully effective. It truly is a collaborative effort when you’re looking to integrate IMU data into your athlete recovery programmes and training regimens.

Teamwork, right from the start of talented athletes’ careers, is the key to future success. And technology vendors need to see themselves as part of that team. The improvements that are coming down the line – in terms of wearable IMU sensors and in terms of the real-time availability of visual and numerical data – are not just an academic exercise. Unlike the sports in which they compete, athlete recovery is no game. And this is where IMUs, even more so than athlete GPS, can focus on giving teams and athletes a much better understanding of the human body’s movement and how to diagnose and repair it.