Motion analysis: wearable sensors versus laboratory

In professional sports, motion analysis helps improve an athlete’s performance and avoid injury. The process is complex and therefore conducted in dedicated laboratories. At the virtual MEDICA MEDICINE + SPORTS CONFERENCE 2020, Prof. Stephan Odenwald explained how motion analysis could become more widely accessible in the future thanks to mobile, wearable sensors.

In this MEDICA-tradefair.com interview, he talks about wearable motion analysis for professional and amateur athletes and explains its advantages over testing in the laboratory.

Prof. Odenwald, you are researching wearable sensors for motion analysis. What types of systems are these?

Prof. Stephan Odenwald: Motion analysis draws a distinction between kinematics and kinetics. Kinematics means we measure the motion of an athlete in space and study the speed, velocity, and position of extremities. Kinetics focuses on understanding the cause of motions and the forces behind movements.

In the field of kinetics, we are developing a system with a sensor sole to measure the ground reaction forces generated by the foot-ground contact. Our field testing corresponds to force plate measurements done in a lab.

What is the added benefit of this system?

Odenwald: Motion analysis laboratories have limitations. Runners only get to run a short distance in a lab or run on a treadmill. The same applies to a cyclist. Yet this does not reflect real-life settings. That is why we aim to collect kinetic and kinematic data outside the laboratory setting using wearable, miniaturized measuring technology.

The advantage is that we create new analysis options, since we go beyond the limited number of captured movements in the lab. We would collect many individual or partial movements during athletic activities instead, which would facilitate a very different type of analysis.

The drawback is that the conditions are not as stable and controlled as in the laboratory setting, which means we also have to manage the effects of environmental factors.

Is this something that would benefit or hinder sports medicine?

Odenwald: For me, the advantages clearly outweigh the disadvantages. In most cases, it may not be necessary for us to calculate the absolute values of force or acceleration. It might be enough to simply get an idea of the scale, make before and after comparisons, or compare movement sequences over time.

You also have to remember that athletes who have access to motion analysis laboratories tend to be privileged. We can make wearable motion capture systems available on a larger scale. We can offer them to athletes who can use them during training or even in competition.

By the way, our task force is not the only entity that works on these types of systems. There are many parties who are currently interested in this subject. It is a big trend in both professional and amateur sports to integrate sensors into sports equipment to obtain objective information. It makes the athlete's performance transparent and affects the way an athlete trains, increases performance and prevents injuries. It also highlights the great potential of these systems since continuous performance monitoring is a tool for competitive athletes to optimize the recovery and regeneration process, allowing them to return safely and quickly to training and competition after an injury. But they also must be mindful and not run the risk of repetitive overload injuries.

Looking back, how do you rate the digital format of the Conference?

Odenwald: I definitely have a positive opinion of the event. Although you lack a feedback platform without direct interaction with the audience – and I admit that I still miss this aspect even after a year of digital education –, I was excited that the Conference could take place online. I also embraced the challenge of speaking to an audience at the intersection of sports and medicine. Other events often only focus on sports and performance and ignore the preventive medicine aspect. I have benefited greatly from the questions people asked after the lecture.