Broad Street runners from Penn are racing with gyroscopes to study the Achilles tendon

Casey Humbyrd, an orthopedic surgeon at Penn Medicine, has never been particularly concerned about tracking stats when she goes for a run.

When people ask her how long it took her to run 10 miles, “I say it took me 10 miles,” she said, laughing.

But when Humbyrd and about two dozen other colleagues from Penn take off on the Broad Street Run this weekend, they’ll be collecting much more data than your typical runner: They’ll be racing with gyroscope sensors fitted to their ankles, for a wide-ranging research project on the Achilles tendon.

It’s a unique opportunity to study the Achilles to learn more about how this crucial tendon works. The sensors will collect data on the runners’ stride length, step count, impact on the ground, and other metrics that can help researchers understand more about how a healthy Achilles functions.

The Broad Street Run is a particularly good spot to gather data: Since runners pass through a number of electronic gates that track their performance, the researchers will also be able to use data from the course to compare to the information they collect from the sensors.

“We can correlate the sensor data with their real-world running performance,” said Josh Baxter, the director of Penn’s Human Motion Laboratory, who will analyze the data collected from Sunday’s run.

Both Baxter and Humbyrd, the chief of Penn’s Foot and Ankle Division, have been studying the Achilles tendon as part of the Penn Achilles Tendinopathy Center of Research Translation, a research center launched with an $8 million federal grant last year.

The Achilles tendon, the biggest in the body, connects calf muscles to heel muscles and is crucial for walking and running.

“It’s part of what makes us human — walking on two legs instead of four. Without the Achilles, that doesn’t happen the same way,” Humbyrd said. “And it’s the only tendon named after a Greek demigod. They knew, even [thousands of years ago], that if you took out someone’s Achilles, they were done.”

Because of its importance in movement, the Achilles also undergoes a lot of wear and tear.

“When you take a step down the street, you might be loading the Achilles tendon with two to three times your body weight. On a run, it might be four to five times your body weight,” Baxter said. “It’s a tissue that’s exposed to lots of loads all the time, and when those loads become damaging and you become injured, it limits your ability to function and have a normal, healthy life.”

But doctors who treat Achilles injuries often see patients only after the injury has occurred. That makes it harder to determine how their tendon wore down, and what strategies might have prevented it.

“We want to catch people when they have pain, but not so debilitating that they need surgery right away,” Baxter said. “Our lab is really focused on trying to identify the early signs of tendon pain and dysfunction, and activities that individuals use that lead them to worse pain.”

In the last year, researchers at Penn’s Achilles Center have analyzed the Achilles on the cellular level — using discarded tissue from tendon surgeries — and studied how to improve physical therapy for people with tendon injuries. They’ve worked to better understand how a healthy Achilles affects movement and use that knowledge to treat — and prevent — tendon injuries.

“The Achilles is the most important part of how your foot communicates with the ground, and I suspect that there are things that people are doing when they move that make them more or less prone to injury [on the Achilles],” Humbyrd said. “But trying to figure out how to optimize those components is really challenging.”

Collecting data from the gyroscope sensors is one way to figure that out, Baxter said. Though many everyday technologies now include gyroscopes — including your average smartphone — they’re imprecise ways to collect the kind of data the Achilles Center is looking for.

“If you’re holding your phone in your pocket, it tells you where your body is moving, but not really your foot or ankle. If you secure it close to the joint or tissue you care about tracking, it will give you a better predictable value,” Baxter said.

Next year, the center hopes to expand its efforts at the Broad Street Run, following more runners as they train for the course.

Humbyrd said she and the other Penn employees — nurses, doctors, researchers, and other staff — running on Sunday were excited to collect data for their colleagues. Still, Humbyrd is keeping her personal race goals simple.

“I want to finish,” she said, laughing, “and not rupture my Achilles.”