Biofeedback: Controlling Your Body

Biofeedback is based on the premise that we all have the innate potential to control our bodily functions through focus of the mind. Biofeedback has been shown to be effective at enabling people to gain a degree of awareness and control over their bodies in situations where it was not previously though possible, such as stroke victims suffering paralysis.
Using an array of special machines to record and feed back information about muscle movements and skin temperature, it is possible to learn to control processes which we normally take for granted such as heart rate and blood pressure. It is beneficial for general health to be able to control these processes under stress. The machines "feed back" the efforts until eventually you begin recognize and control facets of the stress response by yourself.
Here's a run down on the different types of biofeedback systems:
Electromyogram
The electromyogram (EMG) is a machine used to measure levels of tension in the muscles. Two electrodes are placed over whichever muscles are to be monitored. The sensors are usually placed on the forehead, jaw muscle and shoulder muscles. The EMG is often used in the rehabilitation of stroke victims. The EMG can detect electrical impulses even in paralysed limbs.Most often EMG methods are used to help patients learn how to relax and control their body's responses to stress. As the electrodes pick up muscle tension, the EMG emits a sound signal or shows a coloured light, this enables the patient to become aware of muscle activity and to learn what it feels like, so ultimately it can be controlled without the use of the EMG.