A virtual "body double" system that could help fitness fanatics or people trying to regain movement after an illness has been developed.

Many people who have survived a stroke have the ability to be physically active but aren't, according to research published in the journal Stroke. More than half of the stroke survivors (58 percent) did not meet recommended physical activity levels. Physical activity and exercise is such a key method to reduce the risk of a second stroke. We really need to get the message out to these individuals, their families and health care workers that regular physical activity is an essential lifestyle modification for people who have had a stroke. Pioneered by Dutch researchers, the Human Body Model, developed by Motek Medical in Amsterdam, the Netherlands uses a virtual double to show which muscles a person is using by highlighting them in green, reports New Scientist.The force being generated is shown by the intensity of the colour.

Currently, the system is being tested at the Sheba Hospital in Tel Aviv, Israel. The user must don a suit which has 47 reflective markers pointing to specific muscles. They then undertake exercise such as running or walking on a treadmill or pushing weights while infrared lights and cameras are used to track the markers. Sensors on the floor are also used to measure the force applied to the ground by the user's feet. This information is then fed into a computer and the results projected onto a screen, the BBC reported. "It allows you to see the muscle groups you are using in real time, and even the forces they are creating, which are usually invisible," says Oshri Even-Zohar, who developed the system. But he conceded it could not show every muscle at work. "There is no tool in medical science that allows you to measure all the muscle forces in motion," the expert added.