Preventing running injuries by managing load on muscles and bones

Every year 1 in 2 runners get injured

According to The Harvard University Gazette, 30-75% of runners get injured annually. The majority of running injuries (76%) occur in the ankle, knee (e.g. runner’s knee) and lower leg (e.g. shin splints).

Unfortunately, the injury itself is not the only problem. Also, performance can drop over time. If marathon runners recover from an injury (e.g. after 7 days of rest), their marathon time will likely increase by 5-8%. So instead of finishing in 03:45 (hh:mm), they will finish in around 04:00 hours.

According to recent literature, 1 main factor can be linked to the majority of injuries.

The importance of managing load on muscles and bones

Every time your foot hits the ground, there’s a certain amount of load (or stress) on your muscles and bones, which is necessary to keep you going. This load is different from your training load (e.g. your heart rate), which is much more related to performance. Science shows that most running injuries (80%) are caused when the load your bones and mucles experience becomes too much to handle. 

“80% of all running injuries are caused by too much load experienced by your muscles and bones.”

Overloading your body does (most likely) not occur within a single running session, but over a certain period of time and is related to many running injuries such as shin splints, (tibial) stress fractures and patellofemoral pain. 

Evidence-based advice on how to avoid injuries when running

Too much load turns out to be the most important cause for a lot of running injuries. To tackle this problem, runners need to have a better understanding about this load concept.

Until now, the amount of load runners experience was only measured in well-equiped and therefore expensive lab-settings. Recently, researchers found that there's no 'one-size-fits-all' solution (for example a 'correct' running style, running shoe or surface) to run injury-free. That's because the load runners experience is highly individual. 
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Recently, a spin-off from Ghent University called OnTracx, founded by 3 PhD's in running biomechanics and rehabilitation sciences, found a way to measure this load also outside lab settings based on smart biomechanical algorithms and sensor technology. This way, runners and healthcare professionals can apply this load concept to run injury-free or to optimize rehabilitation - both indoors and outdoors. The innovative sensor technology measures the impact forces (the ‘shock’ when your foot hits the surface) absorbed by your entire body during running, which is an important load metric.

This load (Force = mass * acceleration) is expressed in g-forces. The OnTracx sensor measures the load of every step you take, and provides feedback on the total (accumulated) load of an entire running session. By doing so, it automatically accounts for all factors that influence the load you experience, such as your running shoes, your running style and the surface you run on.

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How the OnTracx sensor can help you prevent (re-)injuries

1. See your real-time load, live when running to determine the right intervention to decrease the load of each foot strike.
2. Analyze the total (cumulative) running load of your entire run to plan your week to stay within your safe load progression zone.
3. Discover load trends over multiple weeks, necessary to avoid overloading & running-related injuries.

6 tips on how to manage load to avoid injuries when running

Load depends on several factors, which can differ per runner. While some runners may benefit from switching to more soft running surfaces like grass, others may see an increase in running load. That’s why - according to recent scientific findings - it’s so important to measure that load for every run. 

‍Here are 6 tips on how to manage running load to avoid running injuries:

1. Gradually increase total load
2. Listen to your body and track a pain score
3. Adjust your running speed
4. Find the ideal surface to run on
5. Finetune your running technique
6. Use comfortable running shoes

Let’s dive a little deeper into each tip and learn what scientists have to say about it.

‍"The influence of running surfaces on load can be very contra-intuitive." - dr. Kristof De Mey

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1. Avoid running injuries by gradually increasing total load

A well known method to prevent running injuries states that you should not increase training volume by more than 10% per week. Unfortunately, science shows that this 10% method does not prevent running injuries at all. It’s not even significantly safer than a standard training program that doesn’t use the 10% method.

When you increase training volume by 10% week-by-week, the load you experience could increase by 20% (or more) due to the way you run (your running style), the running shoes you wear, the surface you run on, and so on. This could explain why the 10% method does not prevent running injuries: load is the main cause for running injuries, not training volume.

‍"Two people running the same distance at exactly the same pace and on the same surface can experience up to 30% difference in the load on their body, because of subtle differences in for example running style. As such, running schemes based on volume don’t tell the entire story, and (injury-prone) runners should pay attention to their load profile." - dr. Senne Bonnaerens

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Researchers argue that it makes more sense to gradually increase load, instead of looking at volume only.

OnTracx does exactly this, in a very easy and straightforward way. It tracks your load (progression) and compares this week’s load to previous weeks, thereby promoting a steady progress and avoiding overloading.

The load profile shows both your increase in load (%) and your pain score. In the example below, the experienced load of the current week is >45% higher compared to previous weeks, indicating overloading and thus an increased risk of overuse injuries in the future. 

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2. Run injury free by listening to your body

Remember the last time you got injured? Did you continue running while you noticed discomfort long before? It’s easy to ignore signals from your body in the early stages of injury. But remember: preventing an injury is better than treating one.

Try to stay away from running injuries by entering a pain and comfort score after every workout. Rate your pain or discomfort on a scale of 0-10, and decrease running load when these subjective scores are trending in the wrong direction.*

*Always consult a running professional in case of perceived symptoms or complaints.
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3. Adjust your running speed to prevent getting hurt

The slower you run, the lower the load on your knee per stride. So if you aim to prevent knee injuries, you could decrease your running speed. But by how much?

The decrease in load when running 1 km/h slower, differs per individual. Literature shows that sensors like OnTracx can quantify the load, depending on running speed. This allows you to see your load in real-time, while adjusting your running speed.

Does your training program require you to run at high running speeds? No problem, but know that increasing speed can drastically increase the load. As long as you don't increase the total load of your session (or week) too much and you don't experience any pain, go ahead!

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4. Choose your running surface wisely

If you’re trying to prevent an injury, experiment with running on a softer surface.

Literature shows that some runners experience greater impact forces on concrete compared to synthetic track, grass or wood chip trail. However, some runners do not benefit from running on a softer surface. Or worse: they experience a higher load.

So before you turn straight to trail running, keep in mind that uneven terrain, slippery surfaces and elevation differences can impact load in a negative way.
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‍"OnTracx sensors sometimes reveal a hidden truth: some runners on woodchip trails unknowingly increase their load. While the soft surface seems gentler, it could subtly also alter running mechanics, potentially leading to higher loads. This adaptation—invisible to the naked eye—underscores the importance of precise measurement in understanding running biomechanics." - dr. Rud Derie

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Here’s how you can experiment with running surfaces, just like scientists do in their research

1. Wear an accelerometer that accurately measures running impact forces, like OnTracx.
2. Run on different surfaces, using the same running speed.
3. Analyze the effect of running surface on running load, using the post-run load map or the real-time data.
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5. Finetune your running technique to avoid running pain

Improving your running technique can prevent injuries and pain.Science looked at many aspects of running technique, like: running cadence, stride length, footstrike (forefoot vs midfoot vs heel) and vertical oscillation.

Some of these studies show trends on a group level, e.g. an increase in running cadence leads to a decrease in peak force. This can help to prevent running injuries. However, it also becomes clear that there is no 'one-size-fits-all' way to prevent running injuries by changing running technique.

In other words, avoiding running injuries via technique improvements requires an individual approach.Learn whether you are better off with an increase in cadence or a change in footstrike. Measure your load in real-time, while experimenting with your running technique. 

Again, OnTracx is here to help: Always adjust your running technique gradually, while keeping an eye on both your load and your pain scores (in the OnTracx app).

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6. Run with comfortable running shoes

While some shoes are made to be fast, others are meant to prevent injuries. Running shoes can directly impact your running style: ground contact time, footstrike, pronation and stability.

So far, science shows no clear reduction in injuries when comparing different types of running shoes. In other words: finding the right shoe for you, takes - again - an individual approach.

Moreover, the best running shoe to prevent injuries may also vary depending on the terrain (trail shoes vs track shoes vs road shoes etc.).

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‍"Just because a shoe is cushioned doesn't mean it's automatically reducing the load. We sometimes see in the data that a runner with a more cushioned shoe might experience higher load due to their running style, stride length, or even the specific design of the shoe. It's a reminder that shoe choice is a complex equation, and what works for one person may not work for another. Don't just focus on cushioning; consider how the shoe interacts with all other variables and ultimately influences the load you experience." - dr. Rud Derie

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OnTracx allows you to compare your running load between shoes. Simply place the OnTracx sensor on your shin and start running, using different running shoes. You can analyze the load real-time, or after your test run.

Summary: how to run without getting injured?

Most running injuries are very complex by nature. However, the key to prevention is becoming more and more clear: avoid accumulating a load that your body is not (yet) able to handle.

The challenge to pain free running is accurately measuring and tracking your personal load. That is because load goes far beyond mileage.

OnTracx helps you to track impact forces while running, just like scientists do - for every step you take during your run. It does so with a simple and affordable sensor that connects to the OnTracx app - while keeping it easy and straightforward.

Of course, this is only the start, and we're continuously working on improving the system based on the latest science and feedback from users. One thing is clear: this is the way to go. That said: please continue to work with your trusted running professional or (para)medical expert in combination with using tech as OnTracx.