A SYSTEM that creates a virtual body double of a person鈥檚 skeleton and muscles could help fitness fanatics or people trying to regain movement after an illness by showing them how well they are exercising.
The Human Body Model, developed by in Amsterdam, the Netherlands, uses a virtual double to show which muscles a person is using by highlighting them in green (see image). The force being generated is shown by the intensity of the colour. 鈥淚t allows you to see the muscle groups you are using in real time, and even the forces they are creating, which are usually invisible,鈥� says Motek鈥檚 founder Oshri Even-Zohar. The user鈥檚 on-screen output is not a direct measure of their muscle activity, but is based on existing models of the anatomy and physics of the human body and is intended as a tool to help the patient.
Users carry out exercises, such as running on a treadmill, while wearing a suit with 47 reflective markers placed in the positions of specific muscles. Infrared strobe lights, flashing several hundred times a second, help eight cameras to track the markers. The motion capture system was provided by UK firm . Sensors on the floor of the treadmill can also be used to measure the force applied to the ground by the user鈥檚 feet to give more information on their muscle output and the load on their joints.
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The final stage is to feed this information into computer models, which help create the detailed on-screen display of the user.
The software used to help create the double was trained by directly measuring the force generated by people鈥檚 muscles while recording their motion and the electrical activity of their muscles. This could only be done for some movements and forces, though, such as pushing against weights. 鈥淭here is no tool in medical science that allows you to measure all the muscle forces in motion,鈥� says Even-Zohar.
The system is being tested at in Tel Aviv, Israel, where it is helping people regain movement after a stroke. Researchers at the in Ohio are also using the system to study gait and locomotion in healthy, active people.
