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Delivering Insights, Not Data – How to convert IMU data into actionable rowing insights with New South Wales Institute of Sport’s Damien O’Meara

By December 16, 2021 Article, Customer Win

Damien O’Meara is a biomechanist at the New South Wales Institute of Sport (NSWIS). He works with a variety of Olympic and Paralympic sports, most notably men’s and women’s rowing. A big part of Damien’s role is to build systems that allow other members of the support team to effectively answer complex questions. This in turn helps coaches make more informed decisions. 

Damien considers his role as ‘delivering insights, not data’, and there is a lot of work mixed with a bit of creativity that goes on in the background to deliver those insights. For example, one way he delivered novel insights to the rowing team was through the integration of various inertial sensors placed around the boat.

“Deliver insights, not data”

“For me, being a sports biomechanist is descriptive, it’s not usually prescriptive. Biomechanists are usually the ones who are measuring motion and I believe that the main element of biomechanics is really about understanding movement patterns.”

“Over the years I’ve worked with many different sports. I’ve used IMUs to look at diving and rotation in the air with gyroscopes, propulsion in track cycling where they throw themselves down the track among other sporting movements. I set up systems and workflows to go from sensors, to analysis and processing and then giving feedback and reports.”

“It’s about that time series analysis that sensor data can provide and organizing the sensor’s raw data into that story of how the body moves. The IMeasureU units that are synchronized and waterproof allow you to combine multiple units to capture multiple body segments to really get an understanding of movement patterns”

Getting benchmark data for the rehabilitation process

The rowing coaches were interested in understanding how each athlete moved through the stroke so any inefficiencies could be identified and worked on.

“In rowing, yes you’ve got to be strong to pull the oar but you need to repeat that around about 260 times to do a 2k race. The effectiveness of the movement pattern is what determines how good that rower is. You’ve got this triple extension driving on the foot stretcher, triple extension horizontally to hold on to the oar.”
“The sequence shown below is of two rowers in a men’s pair. Down the bottom, we’ve got the speed of the trunk in blue, the legs in red, and the arms in green. And each individual has their individual pattern which relates to how strong they are, what their hip strength is, their core strength, the power in the legs, the power in the back and all of that physical competency flows into their pattern.”

Previously, video analysis and more lateral GPS units with in-built IMU’s would have been the main way to collect this sort of data for biomechanists like Damien. However, the use of inertial sensors makes this a lot more time-efficient and increases accuracy.

“Video analysis could be used to look at each cycle by plotting the digitized points but that is very time consuming and lacks accuracy. By combining inertial sensors with gate force and angle measurements we can measure force on the gate and the angle of each body segment, then we can also analyze the boat itself. All these elements help to give us an idea of the performance.”

“We’ve had the Mini Max devices from Catapult on in rowing which were developed at the AIS originally in Canberra in Australia. But these aren’t waterproof as we have found out a few times.”

Providing coaches with more than ‘boat acceleration’

Boat acceleration is a metric that rowing coaches are used to receiving. However, with the inertial sensor system that Damien has put in place, deeper data can be collected, offering greater insight for coaches.

“Boat acceleration is a metric that coaches know very well and it’s been developed over a long time. But with the IMU you can replace that too. As you can see here we can use the four sensors that are synchronized; boat, seat, thorax and handle. The beauty of the IMU units being synchronized and also waterproof is that it’s perfect for this job, being able to activate them from an iphone inside the coaches office. That workflow is absolutely perfect in this environment as most equipment just doesn’t work or causes an issue being a large distance away.”

Having multiple sensors working together to create a picture of the full movement of the athlete and the boat is key to Damien’s work. 

“The seat represents the leg drive which is why it’s so important to have a sensor attached to it. We can get the boat acceleration and you’ve got your rower doing their thing all combined together. If I was doing a more pure biomechanical assessment, I might actually want the inertial characteristics of each body segment which would allow me to get really granular data. But because we’re looking at sequencing, I’m actually looking at the relative acceleration so I’m subtracting the seat sensor from the boat to get leg drive. The difference between the two is really what we’re after here.”

“Likewise, subtracting the thorax from the feet gives us the effect of the trunk. If you think about the trunk moving, it’s the relative acceleration of that thorax to the seat because the athlete is still sliding back and forth on the seat so that helps us isolate the actual trunk from what the seat or the legs are doing. We’ve got all these moving parts but the IMU’s allow us to piece all that together.”

Deterministic model

Making technical changes to a rowing stroke by using IMUs

Damien has multiple examples of how this data can help inform coaches of technique that needs correcting to optimize the stroke.

“One specific example was an athlete who was opening up the trunk too early and having this data where they can see the legs, trunk and arms it’s clear where they’re getting out of sync”.

A second example was very similar but where an athlete was pulling on the oar too early and therefore not fully driving the legs before the upper body kicked in. The coaches talk about the athletes having to hang, so extending your legs and not pulling right away. Effectively ‘hanging’. They’ll actually say ‘don’t pull the oar, push the foot stretcher’. So rowing isn’t about pulling it’s about pushing and these cues are all connected to the mechanics that the sensors can help provide objective insight on.”

A biomechanist’s role is to ‘deliver insights, not data’. Through his work with the men’s rowing team, Damien has successfully delivered those crucial insights with the help of inertial sensors and IMeasureU. Identifying energy leaks through detailed analysis of movement has given the rowing coaches opportunity to improve technique based on objective numbers, complementing their coaching eye.

Learn more

This case study builds on concepts we’ve explored in-depth at IMeasureU. Follow the links below to learn more –

Practical Examples of Using IMU-Step to Modify Outcomes: Asymmetry and Impact Load in the Real World – a webinar with Andrew Gray

Understanding External Biomechanical Load During ACLR Rehabilitation – A webinar with Mark Armitage

Set Up for Success with Inertial Data – A Case Study with the Wests Tigers

Have an injured athlete? Get in touch with us and ask about a free demo of IMU Step to see how we can help your return to play.

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