NEW YORK (Reuters Life!) - Health and fitness experts agree that aerobic exercise, whether accomplished by treadmill, bicycle or sidewalk, is the workout way to take good care of your heart.
But they say increasing evidence shows weight, or resistance, training and flexibility also have their parts to play.
"As I tell my patients, it really is survival of the fittest," said Dr. Barry Franklin, director of cardiac rehabilitation and exercise laboratories at Beaumont Hospital in Royal Oak, Michigan and spokesperson for the American Heart Association.
"We have unequivocal data that people who are physically active have 50 percent lower incidence of cardiovascular disease than their sedentary counterparts," Franklin said. "The higher the fitness, the lower the mortality."
Franklin said escalating studies suggest complementing that treadmill time with resistance and flexibility training helps maintain muscle tone and burns additional calories.
Heart disease is the leading cause of death for both men and women, according to the Centers for Disease Control and Prevention. Every year about 785,000 Americans have a first heart attack.
Franklin said an effective cardio workout varies with the exerciser's age and level of fitness.
"Probably most of us, including myself as a researcher, overestimated the intensity we need to improve heart/lung fitness," he said. "We now recognize that between 40 to 50 percent of (a person's exercise capacity) is the threshold."
The method of calculating that capacity, called the theoretical maximum heart rate, has changed as well.
"The old formula (220 minus the age of the exerciser) was created many years ago, based on a 40-year-old male," explained Kerri O'Brien of Life Fitness, the equipment manufacturer.
In 2009 the American College of Sports Medicine suggested a new equation - 207 minus (.7 x age). O'Brien said what the updated formula loses in simplicity it makes up for in inclusivity.
"The new formula flattens out the slope, decreasing the intensity for kids, increasing it for seniors, and leaving the mid-range relatively unaffected," she explained, adding that the formula applies to those with a normal, healthy heart history.
"The heart is a muscle and you should use it," Franklin said, "but recognize it's fed by tiny coronary arteries about the size of cooked spaghetti that have the potential to clog with plaque and cholesterol due, to a large extent, to inappropriate lifestyle."
Exercise, he said, is a double edged sword that protects against, but can also trigger a cardio vascular event in people with known or hidden heart disease.
"We see that with older adults who shovel snow," he said.
The good news is that those who are least fit, the group researchers call the bottom 20 percent, stand to reap the greatest rewards from a fitness regime.
"It's not the person who's already doing 30 minutes who is going to do 35, but the person who was doing nothing and starts doing 10 or 15 minutes of regular walking who stands to gain the greatest benefit," Franklin said.
He believes that demanding minimum exercise guidelines can dishearten Americans too time-pressed to comply.
"I think we discourage the hell out of people," he said. "If a patient tells me they read a new study that they need 30 to 60 minutes of regular exercise, my answer is always the same: what are you doing now?"