New exercise Knee extension: "A really useful addition!"

The most important movements of the knee joint are bending (flexion) and straightening (extension). Straightening the knee, or extending it, is a common exercise for the geriatric patient to train the strength and mobility of the lower extremities. To provoke full knee extension, we added a new game to the SilverFit 3D: “crossing ants”. Why and how did we develop this game?

How it was before

For a while now, patients can use the SilverFit 3D to train their mobility and strength of the lower extremities. Several exercises are available to perform a tapping movement with the feet or make an extension with the knee. The ‘Picknick’ game is an example of this. In this game, bugs appear on a picknick plaid. By tapping the feet or extending the knee, the patient scares the bugs away from the plaid.

The Picknick game on the SilverFit 3D.

SilverFit users’ feedback

Earlier, it was not possible to perform a full knee extension in a SilverFit 3D game. While developing the new update for the 3D, we collected feedback of our users. A lot of our users indicated the need for a game that stimulates the performance of a full knee extension. We received this valuable feedback of physiotherapists, ergo therapists, fitness specialists, care takers, etc. by e-mail, phone, at meetings and trainings. We appreciate this feedback and willingly process it in the development and improvement of our software.

Inventory of needs

Developing a new game starts at the inventory of possible therapeutic goals based on literature and clinical experiences of therapists. At SilverFit, we work in a team of (para-)medical experts, consisting of physio- and ergo therapists, speech language therapists and movement scientists. Concerning the development of the knee extension game, our geriatric physiotherapist researched the demands of this exercise. She examined questions like: For which patients do colleagues use this exercise? What is the evidence in scientific literature? How long do people train on average? What are the settings of this exercise?

A broad target group

Early in the research process, it showed that the knee extension movement mostly is used by physiotherapists with a great spectrum of geriatric patients. This entails for example persons who got a total knee protheses (TKP) or a total hip prothesis (THP), a patient who suffers from arthrosis, a patient who got a stroke, or a patient whose goal it is to maintain muscle strength. By doing a knee extension exercise, the patient trains muscle strength in the upper leg muscles (extensors) and the range of motion (ROM) and coordination of the knee joint. The exercise is important for maintaining independent functioning in daily life (walking, standing, sitting). For most geriatric patients, this is the most important goal of doing the exercise.

Static and dynamic knee extension

Our research showed that there are two options to perform the exercise: static and dynamic knee extension. In other words, extending the knee for a longer period of time or repeating the movement multiple times in a row. These are both important movements for strength training. We wanted to make it possible to perform both options of the exercise on the SilverFit 3D, and also give patients the option to perform this exercise bilateral (for both legs) and unilateral (for one of the legs).

A ‘design sprint’

A new project always starts with a design sprint. Here, a team consisting of a therapist, a game artist, a game designer and a programmer comes together for one or two weeks to work on a prototype. During the design sprint, we for example thought about visualisation: ‘does the player (e.a. the patient) plays the game from a bird perspective or a frontal perspective?’, ‘do we want to display a character?’ and ‘what is the most clear way to show the movement on the screen?’

From prototype to game

After making a prototype, our programmers and game artists get to work to develop the game. During this process, they visit a location every two weeks to test the game in real life with therapists and patients. Thanks to these test sessions, the game gets improved based on users’ feedback.

The knee extension game

The new knee extension game we made, is played as followed. On the screen, we see ants whose goal it is to collect pieces of fruit. However, a cliff separates the ants from the place where they gather the fruit. By extending one or two legs, the patient makes a boulder appear so the ants can cross over. For every piece of fruit that is gathered, the patient receives points.

During the test sessions, we tested how fast the ants had to walk, how clear the game’s feedback is to the patient, if and how the patients could cheat and which elements therapists would like to manually alter on the game’s settings. In one of the test sessions, it turned out that some patients wanted to keep their leg up in the dynamic version of the game. By adding a game element –  a big bug that steals the fruit (points) – the patient is challenged to bend the leg for the time the bug appears on screen, so they keep their high score of points.

The Ants Crossing game on the SilverFit 3D.


The game’s intensity can be manually altered for individual patients in the settings menu:

  1. One can choose to train bilateral or unilateral movements and to train the affected leg or the non-affected leg.
  2. When a patient is not able to fully extend the knee, one can choose the option ‘partial flexion’ (25 or 45 degrees flexion).
  3. One can choose to perform the exercise static or dynamic. For both options, a pause timer can be set.
  4. For the static option, one can decide how long the left and/or right leg has to be extended.

just as with our other games, one can decide on the time period of the game and safe these manual settings for each individual patient.

Finding errors

During the development of the game, and when the game is finished, our tester makes sure that no errors appear in the game. What happens when someone is playing while sitting on a very high or very low chair? Or when someone only has one leg? In all these cases, the exercise has to be adjusted. So called ‘bugs’ (errors) that appear during this test phase, are solved by a programmer

Risk evaluation

For every new game, an update of the risk evaluation is made by our quality officer. Are there any hazardous situations that could happen while performing the exercise? If so, what can we do to avoid these?

Almost done

The exercise game then is added to the advice menu by our medical expert team. They determine to which treatments this game belongs. With a new game, the user manual and training materials also are altered (in 10 different languages!).

Installation of the update

When the update is finished, it is distributed to our customers. When we receive feedback as stated in the quote below, it makes us very happy!:

"“I installed the update on the SilverFit 3D and it worked out just fine. The new exercise “crossing ants” is a great addition. I am using it quite often already. In rehabilitation, the extension strength of the knee has to be trained often and this exercise fits that goal perfectly.”   - Henk Hoeben, geriatric physiotherapist at Zorggroep Noorderboog, The Netherlands

The SilverFit 3D at your location

Would you like to know how the knee extension exercise game works for your patients? Do you have a question or would you like to know more about the (new) possibilities of the SilverFit 3D? We gladly demonstrate our products at your location, without obligation.  

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