That's the suggestion of a new study that says the more vigorous your workout, the better it is for your heart.
The research was conducted at Belfast University in Northern Ireland, where doctors found men who worked their body the hardest saw the most significant reduction in premature cardiac death, compared to those who exercised less vigorously.
However, American doctors take exception with the conclusion, noting that, while more exercise may be better, lesser amounts have value as well.
"While this study emphasizes the benefits of heavy exercise over lighter activity, it does not prove that lighter exercise has no value," says New York University cardiologist Dr. Dan Fisher, who did not participate in the research. "And we should not take this finding to mean that only heavy exercise is good for the heart."
Fisher says any level of activity is better than no activity, with many studies illustrating that moderate workouts done on a regular basis have important heart-healthy benefits -- a tenet also endorsed by the American Heart Association and others.
Asked to comment on the research, cardiologist Dr. Jeffrey Borer says any value in this study must be seen in the "bigger picture," with an overall message that any exercise is good for the heart.
"The inference you would draw from this is that exercise is a good thing because it does reduce the risk of cardiac events and cardiac death, and that the benefits seem to be related to the intensity rather than the duration of exercise," says Borer, chief of the Division of Cardiovascular Pathophysiology at New York-Presbyterian Hospital.
However, says Borer, it's not possible to draw conclusions concerning the benefits of lesser exercise -- or to infer that less exercise isn't worthwhile.
"This is an epidemiological study that looks only at statistics, plus there is no control group, so the amount of information that we can gather from this particular study is somewhat limited," Borer says.
The study was just published online by the British Medical Journal specialty publication Heart.
The 10-year project initially involved some 2,500 men, aged 45 to 59 years old, with no evidence of heart disease. The participants, all living in Cardiphilly, Wales, answered a questionnaire detailing their medical history, usual level of leisure and work-time physical activity, and information on lifestyle factors, including diet and smoking.
Their levels of activity were then classified into the following three categories: light (walking, bowling, sailing); moderate (golf, digging, dancing); heavy (climbing stairs, swimming, jogging).
The final study group was whittled down to slightly more than 2,000 men, who were examined at regular intervals over the 10-year period. During that time, researchers documented 252 deaths, with 193 men succumbing to heart disease or stroke. Among those who died of cardiac-related ailments, researchers found those who participated in the most aggressive physical activity lived the longest, while those who performed less vigorous activity died sooner.
While the level of activity mattered, ironically, the total number of calories expended while exercising did not. The study found that men who regularly expended energy equal to nine minutes of jogging or seven minutes of stair climbing -- roughly 54kcal -- lived longer than those who walked or did ballroom dancing for 90 minutes, expending some 343kcal. (A kcal -- or "kilocalorie" -- is the amount of heat required to raise the temperature of 1 kilogram of water by 1 degree Celsius).
Still, doctors reviewing the research say people shouldn't take the study findings to mean that lower levels of exercise aren't beneficial to the heart.
"Although this study demonstrates you might get more benefits from heavy exercise, any level of activity has important health benefits, including reducing cholesterol, blood sugar and blood pressure levels, all of which benefit the heart," says Fisher.
He also cautions against engaging in heavy or strenuous exercise without proper conditioning.
"The message you don't want to take away from this study is that you should jump from a sedentary lifestyle into heavy exercise. This won't help your heart and it might even cause you harm," says Fisher.
Instead, Fisher and Borer say, get your doctor's advice on the best exercises for your fitness level and gradually expand your workout regimen as your strength increases.