When a leg artery becomes blocked, it leads to poorer circulation and other difficulties in a sufferer's leg. A recent study shows that a walking-based exercise program can mean the difference between an improved ability to walk and a decline in that ability for those with a leg artery blockage.

While some people with PAD experience leg pain, most do not.

As people age, their arteries tend to accumulate plaque, which reduces blood flow. If you've ever seen the deposits on an old water pipe that's being replaced, you have an idea of what can build up inside an artery over time. When this occurs in the legs, it's known as lower extremity peripheral artery disease or PAD.

PAD is estimated to affect one out of every 16 adults over the age of 40. The reason this is only an estimate is because PAD often goes undiagnosed. While some people with PAD experience leg pain, most do not. It can be diagnosed by measuring the difference in blood pressure between an ankle and an arm, but this isn't always done in the absence of pain. With or without pain, PAD decreases the abilities of a sufferer's legs.

While walking is a standard recommendation for those with PAD, previous studies of PAD have been on patients with leg pain. A recent study at Northwestern University tested the effects of a walking program on 156 patients, both with and without leg pain, who had been diagnosed with PAD. After six months, those who followed the exercise program were able to walk an additional 69 feet during a six-minute corridor walk.

Sixty-nine feet may not sound like a great deal of improvement, but when you consider that those who didn't exercise saw a 49 foot decrease in their six-minute walk distance, walking exercises meant the difference between improvement and deterioration. This improvement was also reflected in a questionnaire the subjects filled out which evaluated their quality of life.

The recommended program is a 40-minute walk, three times a week for six months. While the walking can be done either on a treadmill or outdoors, study lead author Mary M. McDermott, a professor of medicine at Northwestern University's Feinberg School of Medicine, says it's best done with a trainer. "You need a trainer, because if you start to get symptoms, you can stop and then start again until you have done the 40 minutes."

While the exercises were done on a treadmill, walking ability was tested by a corridor walk. Treadmill performance is susceptible to a learning curve. And obviously, everyday walking is more likely to occur on the ground than on a treadmill.

The study also tested the effects of leg resistance (strength) training. Participants who did such training for six months showed no change in their six-minute walk distance. They did show improvement in other areas, including walking endurance on a treadmill and their quality of life evaluation. But strength training was not as beneficial overall as walking exercise was.

The study was published in the January 14, 2009 issue of the Journal of the American Medical Association (JAMA).