The problem with T-rex arms in VR rehab

One of the main challenges we are trying to solve at the moment is that people don’t stretch their arms enough while using VR.

Why is this important?

When people stretch their arms they are increasing the amount of force on the shoulder ie. more resistance in the exercise.

But more importantly when people stretch their arms they are getting more correct anatomical movement and thus a higher quality of therapeutic treatment.

Anatomical movement is critical for rehabilitation because you need to use the entire range of motion to regain full range of motion after injury.

In VR people will move the way that’s most economic and most games don’t facilitate stretched arms or anatomical movement most of the time. And when you are using VR to train you don’t have a physical therapist to correct you.


Developers need to add inducements to get the patient to reach and do correct anatomical movement.

But you cant get the patient to reach in an uncontrolled manner. That would leave them open to damage and possible reinjury.

Also you need some way to control compensatory movements.

So first of all you need something to keep the patient looking straight.

In one of our activities we have an anchor in the middle of the patients line of sight. Activities will not start without the patient holding their head in the right position and they cannot complete the activity without looking straight at it.

Now that we’ve got the head fixed we need to get the patient to move their arm in an anatomically correct way. In our case we are working with correct abduction.

One way we are working with this is to present the patient with a cone next to a representation of their position to guide the movement. If the patients strays from this cone they get an error in the measurement and are asked to repeat the process .

They are now induced to move correctly.

Another way to make sure that the patient is moving correctly is to place a vive tracker on the elbow. This will make sure that the upper arm is moved and it will not matter if the elbow is flexed.

This however takes a lot of programming and most developers are not there yet.

There are a host of ways you could do this and this is just a few.

What are your ideas to get people to move correctly?

Written by:

Jesper Aggergaard

Physical therapist

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