Applications of Physics in
Physical Therapy

Electrical stimulation units use an electrical current to simulate the same electrical impulses that are activated during normal exercise. By passively activating the muscle, the body responds in much the same way as during normal exercise. By placing a pair of electrodes on the target muscle or muscle group, the unit can send electrical impulses through the skin to underlying nerves, stimulating the contraction and relaxation of the muscle in a rhythm similar to daily exercise. Electrical Stimulation can be used for two primary functions; strength training and muscle tone or pain control.

E-stim can be used for muscle training or pain control by placing electrodes on the target muscle area.

The EMS (Electrical Muscle Stimulation) unit is used for muscle training. By simulating active exercise, muscles utilize glycogen, fat, and other stored nutrients during contractions. Through continuous use of the EMS, the tetanic muscle stimulation will result in muscle tone, strength, and improve contour.  This method would be most often found in the field of sports medicine and rehabilitation.

EMS can be used to maintain muscle strength during a period of immobilization by passively activating muscle activity.

The TENS unit is used for pain management and control. This is the most common practice found in physical therapy. The TENS unit provides pain relief by sending small electrical impulses through electrodes placed on the skin to underlying nerve fibers. TENS is believed to work by two different mechanisms. First, electrical stimulation of the nerve fibers can block a pain signal from being carried to the brain. If the signal is blocked, pain is not perceived. Secondly, the body has its own mechanism for suppressing pain. It does this by releasing natural chemicals called endorphins in the brain which act as analgesics. TENS may activate this mechanism. By effectively managing pain without drugs, TENS allows many people with chronic pain conditions to resume daily activity.

Related Physical Concepts:

• Circuits
• Electrical Fields
• Wave Properties