How to reduce the risk of running injuries – a step in the right direction

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An estimated 50 million people in Europe regularly go for a run, including almost 20% of the Belgian population. While most might not be running marathons at an Olympic pace, the chance of getting injured can feel inevitable to any runner. This fear is justified, as around half of all runners experience at least one injury annually. But what’s driving this unsettling statistic, and how can runners potentially reduce the likelihood of a dreaded injury spell?

Risk factors for running injuries include personal aspects such as age, weight, or previous injuries and training-related factors like distance or frequency, with more than three-quarters of running-related injuries resulting from overloading. “Most running injuries are actually overuse injuries, which means that they occur when the cumulative load, the total load over time, becomes too much,” explains Senne Bonnaerens, Ph.D. running biomechanics and co-founder and CEO of OnTracx, a spin-off company from Ghent University developing wearable load-sensing technology. “It’s not that you get injured instantly, but after weeks of running. Because that load continues to increase, it becomes too much, and then you get injured.”

What is load when running?

Mechanical load is a general term referring to the forces on your body, and when running, there are two main load parameters. The first parameter is the impact that occurs the moment your foot hits the ground. The resulting shock mainly goes through your bones and can lead to stress fractures and plantar fasciitis, says Bonnaerens. The second parameter is called the maximal load. This refers to when your foot is flat on the ground, carrying your entire body weight upon the knee flexing, followed by pushing up to continue the stride. This maximal load parameter is more related to injuries such as Achilles tendinitis, patellofemoral complaints, and knee arthritis. Each of these parameters has the potential to lead to different injuries, and together they cause “about 70 to 80% of overuse injuries,” indicates Bonnaerens.

But, as Bonnaerens highlights, what’s right for you in terms of load might not be right for your running partner. “It’s very individual, and it depends on how you react to your running shoes, to your surface, to running faster or slower, changing your running style, and so on… There’s not one running style, not one running shoe, not one surface that fits for everyone. That doesn’t exist for injury prevention.”

There’s not one running style, not one running shoe, not one surface that fits for everyone.” – Senne Bonnaerens, Ph.D. running biomechanics and co-founder and CEO of OnTracx

So, what can we do about load?

Good load management when running is increasingly viewed as one of the most important tools in the injury prevention toolbox when it comes to overuse injuries in running.

But how can we measure load?

Previous efforts to quantify load in runners relied on controlled and expensive laboratory testing with advanced camera equipment and force-detecting plates. This is clearly challenging to translate to real-world settings and is out of reach for most runners and healthcare professionals, such as physiotherapists, who might wish to monitor load as part of injury rehabilitation.

Thanks to an increasing variety of wearable technologies, like smartwatches, runners can routinely monitor metrics, including distance, heart rate, and estimated calories burned. But, for now, other innovative wearable technologies focus largely on performance or provide information on how you run in terms of asymmetry and stability but don’t focus on load. For instance, Stryd is a sensor that attaches to shoelaces to measure running power, ground time, and vertical oscillation, allowing users to balance training, recovery, and performance. Similarly, another Belgian spin-off company called Runeasi provides real-world running gait analysis via a waistband sensor focusing on physiotherapy applications and return-to-run rehabilitation. In contrast, the wearable sensors and algorithms that Bonnaerens and colleagues have taken over four years to optimize with lab-based and real-world experiments, focus specifically on quantifying load for every step, even outside of the treadmill lab setting.

With OnTracx, Bonnaerens and colleagues use a sensor the size of a two-euro coin attached approximately 10 centimeters above the inner ankle, combined with advanced algorithms that analyze over 20,000 data points per minute, to accurately measure the peak acceleration the moment a runner’s foot hits the ground. This acceleration measurement is used as a proxy for mechanical load.

“The latest scientific findings show that peak acceleration is really important in injury prevention,” highlights Bonnaerens. This acceleration data translates to a load score provided to the runner via a smartphone application for continual, real-time load monitoring. Combined with a pain score, this load data provides users with robust biofeedback that indicates the possible risk of future injury. “When you see that your load increases 20 to 30% week after week, it doesn’t mean that you will get injured right then. But the risk or the chance of you getting an injury is higher in the future,” explains Bonnaerens.

While their work continues to also quantify maximal load, the hope is that both impact score and maximal load can be incorporated in the future to provide comprehensive biofeedback that the user can act upon in a data-driven way.

The return-to-run rehab reality

These data-driven insights aim to help runners remain in the safe zone without overloading. Healthcare professionals like physiotherapists would also benefit from accurate load measurements for later-stage return-to-run rehabilitation. The load experienced when performing rehabilitation exercises, such as squats, calf raises, etc., is substantially lower than that experienced when running just one step. Similarly, running on a bouncy treadmill dampens the load compared to running outside, where the load is substantially more. This makes reinjury common since the patient feels good during physiotherapy but might get back to running too early.

Bonnaerens explains the possible process: “In subsequent running sessions, the runner can go a little bit longer than before if there is no pain. That’s the way we can steadily increase the load over time. If the runner feels pain, it means that the exercise is too much. You have to start over or have to delay the return-to-run process.”

This is an active area of research, largely driven by user feedback from healthcare professionals, where the need for objective, personalized approaches to load management is crucial. Physiotherapists or coaches need the tools to create a unique profile for each person. In the future, Bonnaerens envisages using wearables to measure load specifically for different areas, such as the Achilles tendon or the patellar tendon: “Perhaps in the future, we will put a sensor on each leg to look at the load measure that matters for there and make a personal solution for every runner.”

“Perhaps in the future, we will put a sensor on each leg to look at the load measure that matters for there and make a personal solution for every runner.” – Senne Bonnaerens, Ph.D. running biomechanics and co-founder and CEO of OnTracx

A helping hand from the Benelux Life Sciences ecosystem

OnTracx is a spin-off company from Ghent University, with support from the imec.istart, VLAIO, BlueHealth Innovation Fund, and Victoris. It is clear that being a part of the Benelux life sciences / health-tech ecosystem was fundamental to getting companies like OnTracx up and running. “I think the life science ecosystem is actually amazing because entrepreneurs help each other. You get connected really easily,” indicates Bonnaerens.