"We found that exercise can act as a medical therapy to improve both sexual function and overall quality of life in these patients," says Romualdo Belardinelli, M.D., director of the Lancisi Heart Institute in Ancona, Italy.

Many heart failure patients take prescription drugs containing nitrates. Individuals taking these medicines are warned to avoid drugs such as Viagra, a prescription drug used to treat erectile dysfunction, because of a potentially lethal interaction between the two.

"Patients who exercise instead of taking drugs to address sexual dysfunction avoid the problem of interaction with the nitrate medicine that many heart failure patients take," Belardinelli says. "In fact, more than half the patients in our study were taking nitrates, and we saw no side effects whatsoever."

Nitrates, combined with Viagra, can cause very low blood pressure and cardiocirculatory shock.

The study indicates that patients who cycled had increased sexual activity and better overall quality of life, which can be traced to better cardiovascular function. Improvements measured in the brachial artery (the artery that runs from the shoulder to the elbow) indicate that blood vessels in other parts of the body also benefited from the exercise, Belardinelli says. He says they do not know whether other types of exercise would have the same effect as cycling.

The study is the first to examine the relationship between chronic heart failure and sexual dysfunction and to show that exercise training can significantly improve a male patient's ability to perform sexually.

Researchers studied 59 men in their mid-to-late 50s, all of whom had stable chronic heart failure caused by ischemic heart disease. This condition can cause blood vessel damage that impedes the flow of blood to the penis and impairs the ability to produce an erection. None of the study subjects had prostate disease, another frequent cause of sexual dysfunction.

One group of 30 patients exercised on calibrated and electronically braked stationary bikes in a hospital-based, supervised program, while a second group of 29 heart patients did not exercise. The first group exercised at 60 percent of their peak oxygen uptake three times a week for eight weeks. Each session lasted about an hour, with the first 15 minutes devoted to stretching and calisthenics exercise, followed by 40 minutes of cycling at the target intensity. Heart rate and blood pressure were checked before, during and after cycling.

At the start of the study and at eight weeks, all participants underwent exercise testing and researchers measured vasomotor responses (dilation and contraction) in their brachial artery. Vasomotor responses were assessed by flow-mediated dilation, which is the reaction of the blood vessel to changes in blood flow. These responses are an indication of a person's endothelial function. The endothelium is the inner lining of a blood vessel that controls dilation and contraction of the vessel.

Researchers quantified quality of life and sexual improvement using questionnaires completed by patients and their partners. Quality of life (QOL) was measured by responses to the Minnesota Living with Heart Failure questionnaire. Sexual improvement was assessed by Sexual Activity Profile (SAP) questionnaires that covered three areas: relationship with partner, quality of erection and personal wellness.

"We found significant improvement in both SAP and QOL among patients who were cycling," Belardinelli says.

After eight weeks, peak oxygen uptake in the cycling group had improved 18 percent and flow-mediated dilation improved 76.4 percent (from 2.29 percent to 4.04 percent). Along with these changes, researchers saw a 76.8 percent increase in SAP scores among participants (from 3.49 to 6.17), and a 97.2 percent increase in their partners' scores (from 2.47 to 4.87). Quality of life improvements were also noted.

There was no change in the group who did not exercise.

"It appears that exercise improves endothelial function in all major blood vessels," Belardinelli says. "This benefit may explain, at least in part, the improvements in quality of life and sexual activity profile."

These are preliminary results in a small group of men, he says. In the future, the researchers will see if this effect can be found in a larger study population.