What Are Force Plates and How Are They Used in Rehabilitation?

Rehabilitation teams use many different tools and assessments to help determine when people are ready to return to sport or daily activities. One type of advanced technology gaining traction in rehabilitation is force plates.

Long used in sports performance training, the use of force plates is becoming more ingrained into physical therapy.

Force plates measure how a person interacts with the ground. They capture ground reaction forces and convert those forces into objective metrics that help quantify movement quality, strength, power, balance, and symmetry. These measurements can help rehab teams:

• Structure rehab programs.
• Track progress over time.
• Determine when a person is ready to return to sport or activity.

Some UPMC Rehabilitation Institute locations are already using the technology.

"The most important part of this technology, along with any others that we use, is that it integrates into our clinical care environment, so that we're using it to make decisions," says Keelan Enseki, PT, physical therapist, UPMC Rehabilitation Institute – UPMC Rooney Sports Complex.

"We're not replacing our eyes, so to speak, and we're definitely not replacing the rationale," he says. "It gives us information, but the most important part of that is what you do with this information. It's just another tool in our toolbox."

Learn more about force plates and how they work in rehabilitation.

What Are Force Plates?

Force plates (or force platforms) are devices that measure the force that people produce against the ground while doing an activity. They have sensors that detect a person's effect against the ground.

"To boil it down to something fairly simple, they are mechanical load cells," Keelan says. "And what they measure is how you interact with the ground."

The force plates collect real-time data as someone performs an activity, such as jumping, squatting, or doing a sit-to-stand exercise. They display a curve of the force change during the activity.

What Do Force Plates Measure?

In general, force plates measure ground reaction force, or the force you exert against the ground. But there are many different metrics that they can shed light on, including:

• Center of pressure (important for balance).
• Jump height.
• Left-right performance symmetry.
• Rate-of-force production.
• Strength.

The same metrics don't necessarily apply to every person, Keelan adds. For example, metrics that measure explosive athletic ability are more important for elite athletes trying to return to sport than for people returning to normal everyday function. So, rehabilitation teams look at different metrics for different people.

"You do have such a large, almost an infinite number, of variables available to you," Keelan says. "We have to, as clinicians, pick out those variables that are most applicable and important to the goals and match that."

Why Are Force Plates Useful in Rehabilitation?

Not every rehabilitation center has force plates, but their use is growing. They can complement the hands-on skills of rehab teams by providing real-time data on someone's progress.

"When we have them available, it gives us additional detail that may be very beneficial to the rehabilitation," Keelan says.

To gather that detail, rehabilitation teams can have someone recovering from an injury perform tasks on force plates. The force plates can capture precise data to complement a robust clinical evaluation, Keelan says.

“These are metrics that we often cannot see with the bare eye clinically," he says.

As an example, he cites a sit-to-stand exercise often used in physical therapy.

"You can look at force distribution from the left to the right," he says. "Are they favoring one side versus the other? Are they less stable on one side? How quickly do they produce force?

"The force plates may give us information that we just don't see visually."

Another example is a standing exercise for someone with balance issues. They can step onto the force plate with one or both legs.

"We can look at their center of pressure and how that is distributed, how it varies throughout the task, and can they hold balance?" Keelan says.

"In the past, we would just say, 'OK, can they balance for X amount of seconds or in certain positions?' Those are great tests; they're validated. Now this will kind of give us a little more idea of not only can they do it, but what is the quality?"

The force plates are also useful because they provide real-time data. Rehab teams can quickly see the data and address any problems.

"It might help us fine-tune our treatment to be more effective," Keelan says.

How Do Force Plates Factor into Return-to-Play?

Whether you're an athlete wanting to get back to competition or you're trying to return to normal routines, force plates can help.

Keelan says that you can use force plates throughout the entire rehabilitation process.

Depending on a person's injury and abilities, rehab teams can have them perform different tasks on force plates. They can analyze the data to determine the patient's progress. That data can help them determine whether the person is ready to move to the next step of their recovery or needs more work.

"If they're doing great or there are no notable issues, that tells us maybe they're ready to progress towards more sport-specific activities in the rehabilitation environment, or at least go back to training," Keelan says. “But if we pick up certain characteristics that could be related to an increased risk of injury or being not ready to return, then it allows us to recalibrate the rehabilitation."

Rehab teams can measure performance compared to prior data and even to other similar patient groups. This information can help give them a sense of a person's progress and their readiness to return to activity.

But while force plate data can be an important variable for return-to-sport, it's not the only variable. Care teams look at many additional factors, from a person's comfort to their range of motion.

"By itself, force plates will neither preclude or absolutely clear somebody," Keelan says. "But really, there's not a single test that would absolutely do that, either. It's part of what we call a return-to-sport battery."

Keelan says that force plates can continue to provide a valuable role in rehabilitation. But they're there to complement the expertise of therapy teams, not replace them.

"We think it's a great tool, but we never replace anything with it," he says. "We just think of it as adding on and giving us the better ability to care for patients."