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MOTI for measuring balance

The R&D team just returned back from the lab where they were investigating whether MOTI could be used to measure balance. In the session, they evaluated the postural sway during two tasks, standing with the feet together with the eyes open and then the same with the eyes closed. What they wanted to investigate was whether the postural sway could be measured with MOTI when compared with an advanced balance platform (force plate). The results are very promising to say the least.

The figures below demonstrate how the subject applied forces in the force platform (commonly named as ground reaction force in research) to maintain balance (figures 1 & 2) and body acceleration measured simultaneously with MOTI (figures 3 & 4). In research, both forces and body accelerations are used as proxy for balance performance. What is interesting to note is that when the eyes are closed, the postural sway increases, indicating a poorer balance performance compared with open eyes. This increase can be seen on figures 2 (force platform) and 3 (MOTI).

Figure 1 Ground reaction forces measured with the force platform with the eyes open

Figure 2 Ground reactions forces measured with the force platform with the eyes closed

Figure 3 Body acceleration measured with MOTI with the eyes open

Figure 4 Body acceleration measured with MOTI with the eyes closed

Figure 5 Raw data for estimation of body sway. Here both conditions (eyes open and closed) for both devices (force platform and MOTI) are shown together.

What is postural sway and why does it matter?

Postural sway is a result of the nervous system constantly monitoring and re-adjusting the body’s position in space. You can try it out yourself. Stand up, put your feet together and find a fixed spot on the wall in front of you. Fix your eyes on the spot and then stand as still as you can for 10 seconds……....Are you done? What you probably felt was that the body was not completely still but rocked a bit backwards and forwards and/or from side-to-side. Now let’s try this: Repeat the task but now do it with your eyes closed……We hope you did not fall. What you probably noticed was that when the eyes were closed, your body swayed more than before. This is because our sight has an important role in telling our nervous system where our body is in space. When these information are removed, the nervous system needs to rely on our other senses e.g. from the inner ear, muscles and joints.

Postural sway is pretty much the technical term for balance. Balance is something healthcare professionals frequently need to evaluate in their clinical work, but this is often done with standardized clinical assessment methods which are highly dependent on the subjective evaluation of the clinician.

When and where is it important to measure balance?

Evaluating postural sway is an important feature to evaluate in cases where balance is considered part of the clinical problem. For example, poor balance related with an increased risk of falling amongst the elderly; a problem that can result in serious injuries and negative consequences on the quality of life. Balance training is frequently used to reduce the risk of falls but currently, it is difficult to evaluate the effect of treatment objectively. The findings from the R&D team (figures 1 – 4) indicate that MOTI can be a very useful tool for such purposes.

MOTI measures the acceleration of the body during quiet standing whereas the force platform measures the dispersion of weight on the platform (ground reaction force, measured in Newtons). Even though the units are different, they tell the same story i.e. when you close your eyes the balance becomes poorer. This is identified by the force platform but also MOTI. The R&D team is currently evaluating how MOTI performs in a larger group of individuals and comparing it to the gold-standard. We look forwards to presenting the results from this work soon, since our preliminary results are very promising. Finally, in Figure 5, it is easier to visualize that the data from MOTI (red lines) shows similar trends compared with the force platform data (blue lines) at the same conditions. This is a crucial step for a reliable estimation of body sway in the future.

Future perspectives on balance measurements

The guys at research and development are currently investigating the possibilities of evaluating more dynamic aspects of balance. Such measurements are highly important in e.g. sporting populations where injuries to ligaments and joints unfortunately occur frequently. We look forwards to presenting the preliminary findings. Make sure you like MOTI on Instagram and Facebook to get notified when we have more news.

Want to know more about MOTI and what it can do? Contact us and we would be happy to have a chat!

MOTI Research and development team

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