Deer hunting could be a dangerous endeavor for men with heart disease or risk factors for it, research findings suggest.

In a study of 25 middle-aged male deer hunters, researchers found that the activities inherent to hunting - like walking over rough terrain, shooting an animal and dragging its carcass - sent the men’s heart rates up significantly.

In some cases, this led to potentially dangerous heart-rhythm disturbances, or diminished oxygen supply to the heart.

Of the 25 hunters, 17 had established coronary heart disease, while the rest had risk factors such as being overweight, smoking or having high blood pressure or cholesterol.

The findings suggest that for men like these, hunting could boost the risk of heart attack or cardiac arrest.

Susan Haapaniemi and colleagues at William Beaumont Hospital in Royal Oaks, Michigan, report the findings in the American Journal of Cardiology.

For the study, the researchers outfitted each man with a portable monitor that continuously recorded his heart’s electrical activity during a day of deer hunting. For comparison, the men also had their hearts monitored as they exercised on a treadmill on a separate day.

In general, the researchers found, deer hunting put the men’s hearts under more strain than the treadmill did. Ten men exceeded the maximum heart rate they logged on the treadmill, and several showed potentially dangerous heart responses to hunting that they did not show during the treadmill test.

Three men had signs of impeded blood flow to the heart during hunting, but not on the treadmill. Similarly, three of the men with heart disease had heart-rhythm abnormalities while hunting that did not show up on the treadmill test.

The combination of physical exertion, adrenaline rush and the stress of rough terrain and cold weather may explain the “excessive cardiac demands” seen with hunting, according to Haapaniemi’s team.

What’s more, they point out, most of the men in the study were taking part in an exercise program to treat their heart disease, or were regularly physically active. Hunting could be an even greater strain on the heart in men who are usually sedentary, the researchers note.

SOURCE: American Journal of Cardiology, July 15, 2007.