People can learn to control involuntary body functions such as heart rate or skin temperature using ''
biofeedback'' machines that electronically monitor pulse rate, brain waves, skin sweat, and other physical responses. Scientific research supports
biofeedback's role in teaching people to relax muscles and so relieve
headaches or persistant back pain, for example, or to control pelvic floor muscles to prevent incontinence. Many doctors believe
biofeedback is set to become widely available in the future.