Approximately one in ten Australians runs regularly, ranging from those who jog a couple of times a week to elite athletes.
Originally driven by pandemic gym closures, the new popularity of running continued to gain pace after the lockdowns were over, with participation in running clubs and events like Parkrun and marathons booming among all age groups.
However, the increase in participation has also led to a rising number of injuries: about half of all runners are likely to sustain a running-related injury in any given year.
Previous studies have indicated the runners whose feet hit the ground hardest, considered high-impact runners, may have an increased risk of lower leg injuries, such as plantar fasciitis and stress fractures, but identifying them without the use of expensive equipment has proved difficult.
Gold standard methods rely on expensive treadmills with built-in force plates that are inaccessible to most runners.
In previous studies, the Macquarie researchers have shown that small accelerometers worn on the ankle can be used as a surrogate measure of impact during treadmill running.
Flexible testing options for coaches and clinicians
For the team’s latest study, published in the Scandinavian Journal of Medicine and Science in Sport, they developed a simple formula for coaches and clinicians to use to identify high-impact runners, regardless of their running speed.
First author of the new paper, Dr Eoin Doyle says previous impact studies have required participants to all run at the same pace.
“The usual speed in these trials is faster than the average pace distance runners prefer,” he says.
“The key difference in our study was that everyone ran at their own preferred speed.
First author of the new paper, Dr Eoin Doyle says previous impact studies have required participants to all run at the same pace.
“The usual speed in these trials is faster than the average pace distance runners prefer,” he says.
“The key difference in our study was that everyone ran at their own preferred speed.
“Running at their own pace, 21 per cent of our runners were classified as high impact, but at the faster pace, that would have nearly doubled to 39 per cent.
“It shows that if someone is running faster during testing than they usually do on the street or the track, then you could be overestimating their real risk of injury.”
Facilitating low impact running
Their study was one of the largest of its kind with 171 runners included. The runners were evenly split between male and female, and represented a range of ages, builds and experience levels. Most were running an average of 40km a week.
Having a large cohort with a wide range of characteristics, the team was able to investigate which factors might influence running impact magnitude, such as sex, age, weight, body mass and experience.
Surprisingly, none of these factors affected how heavily a runner hit the ground.
We are looking at whether we can also identify high-impact runners using commercially-available activity trackers worn on other parts of the body, like the wrist and chest, or clipped to running shoes.
Senior author Dr Joel Fuller says one interesting finding came from the 3D imaging they included in the study, with a clear relationship between impact and the angle of the ankle when the foot hit the ground.
“The people who were in the low impact group were landing more towards the ball of their foot,” he says.
However, instructing people to switch from landing on their heel to the ball of their foot is unlikely to be the solution to reducing injury risk.
“Several research groups have shown that getting a runner who naturally lands on their heel to instead land on the ball of their foot can easily overload the calf complex and forefoot bones.
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“We believe a more appropriate approach is possible by using the accelerometers to provide audible feedback to runners and help them find a suitable low impact running style that works for them.
“This often involves subtle and individual-specific technique adjustments rather than asking the ankle to do it all.
“Out pilot studies suggest this can be achieved in as little as eight sessions, potentially reducing the risk of subsequent lower leg injury.”
Developing affordable options
While clinicians and coaches now have access to the high-impact detection formula developed by the Macquarie research team, research-grade accelerometer equipment is still required.
This leaves most runners with no option but to be on the alert for warning signs associated with high impact, such as loud slaps when their feet hit the pavement or their running shoes wearing down quickly.
Innovation: Dr Eoin Doyle, left, and co-author Dr Joel Fuller, right, are developing ways to measure injury risk in runners using common, commercially available fitness devices.
The team’s next step is to investigate how they can achieve similar results to those they saw in the lab using more affordable devices.
“Currently, we are looking at whether we can also identify high-impact runners using commercially-available activity trackers worn on other parts of the body, like the wrist and chest, or clipped to running shoes,” Dr Fuller says.
“This would open up the possibility of using devices already worn by most runners in conjunction with a smartphone app to give each runner easy access to an impact magnitude rating.”
Runners interested in taking part in future studies are invited to contact the research team by emailing run@mq.edu.au
Dr Joel Fuller is a senior lecturer in the Macquarie University Department of Health Sciences, a researcher at the Macquarie University Performance and Expertise Research Centre, and a qualified physiotherapist and sports scientist.
Dr Eoin Doyle is a lecturer in the Macquarie University Department of Health Sciences, a researcher at the Macquarie University Performance and Expertise Research Centre, and a qualified physiotherapist and exercise physiologist.
