If you've ever sat in one place for a long period of time and then stood quickly, you know the feeling - light-headedness, a tingling in the lower limbs and a heaviness in the legs and feet.

Airline pilots have to contend with this condition all the time. So do people who've had paralyzing spinal cord injuries, strokes, or even hip or knee replacement surgery.

It's what happens when blood pools in the lower extremities. In essence, it is a static collection of blood in parts of the lower body that become immobile for extended periods of time because of gravity or inactivity.

In the short term, the condition, known as deep venous thrombosis, is little more than an annoyance, like having your foot fall asleep. But if the condition persists for a few hours or more, it can lead to detrimental side effects, including the possibility of deep venous thrombosis pulmonary embolism, which can create a potentially fatal blood clot.

Dr. Pouran D. Faghri has been working with a technology that may offer sufferers a shocking new way to avoid the condition. Literally.

Faghri, a medical doctor and associate professor and head of the Department of Health Promotion and Allied Health Sciences, has been using a variety of electrical stimulation systems to the muscles of a variety of patients who suffer from deep venous thrombosis. The results have been encouraging.

"It has worked well in patients who have spinal cord injuries and who have had partial paralysis from a stroke," she says. "I have also finished a recent study that looked at how the system could help patients who were having prolonged surgery such as hip or knee replacement surgery. That was also quite successful."

The system Faghri uses is known as a Functional Electrical Stimulation (FES) unit. The unit includes small electrodes which are placed on the patient's calf and quadricep muscles. Electrical current runs through the electrodes and into the muscle fibers periodically, stimulating the muscle and causing a natural firing of muscle fibers.

"This produces 60 percent of the muscle activation that a healthy person would normally receive from voluntary contraction of their muscles," Faghri says. "This is enough to move the large amount of venous blood back to the heart and keep the tissue fresh."

More than a massage
The FES system is a vast improvement over traditional sequential compression technology, which did little more than massage the muscles. "The other systems don't really move the blood well, especially within the muscle fibers," Faghri says. "And they don't produce some of the other secondary effects, either."

These secondary effects include a toning of the muscles in stroke and spinal cord patients. Along with reducing the potential of pulmonary embolism, this toning can reduce or eliminate ulcers that often develop on the skin covering immobile body parts. In stroke patients with hemiplegia, the toning and increased blood flow from the FES system also can reduce pain that often accompanies their paralysis.

"Stroke patients have limbs that become immobile as a result of their condition," Faghri says. "Their muscles experience dystrophy and there is nothing to support the bones around the joints, especially around the shoulder. Because of this, when we try to move them, they experience severe pain. FES can lessen this pain, especially if it is used early on in their condition."

Because the system is less cumbersome than sequential compression systems, it gives surgeons more flexibility in the operating room. Faghri hopes to refine the FES system to have more general applications.

"I would like to create something that can be easily used by people such as pilots who are on long flights, or passengers on airplanes, or other people who are sedentary," she says. "It can be something as simple as a pair of socks that stimulate the calves or feet periodically."

For those who cringe at the thought of tiny electric shocks going off in their socks, don't worry.

"It is painless," Faghri says. "There is a sensation that lets you know it's working, but it is not painful at all. Most of our subjects actually liked the sensation."

Faghri is testing FES technology at New Britain Hospital for Special Care. She also is planning to use this system to exercise people with spinal cord injuries.

FES will allow people with little or no voluntary leg movement to actively pedal a stationary leg cycle ergometer with the power of their own muscles. This will produce a significant return of venous blood from the lower extremities back to the heart. As a result, more blood will pump out of the heart to the exercising muscles.

The benefits to people with spinal cord injuries will include increased muscle mass, strength and endurance, a relaxation of muscle spasms, improved circulation, and an increase in their range of motion.

"I hope to be able to expand the applications of this technology during the next few years," Faghri says. "It is very exciting because I know it has the potential to provide help to many, many people."