Risks of heart attack increases as one advances in age but a new study suggests that older adults can reduce their risks and even improve their cardiac health by maintaining or even increasing the level of their physical activities.

In a new study published in the in the journal Circulation May 5, researchers followed nearly 1,000 adults who were parts of the community-based Cardiovascular Health Study. The participants, who were 71 years old on average at the start of the study, wore a heart monitor 24 hours daily for a period of five years, during which their heart rate variability, or the time interval between heartbeats, was recorded.

Study author Luisa Soares-Miranda from the Harvard School of Public Health in Boston explained that cardiac health and the nervous system, which regulates the heart, influence the small changes in heart rate variability. Early anomalies in the system therefore manifest as changes in heart rate variability which predicts the likelihood of future heart attacks and even death.

The researchers observed that the subjects who walked farther and faster over the study period had better heart rate variability than the subjects who reduced their pace and their walking distance showing that exercise can contribute to improved heart health and reduce risks of heart problems.

 "Greater total leisure-time activity, as well as walking alone, were prospectively associated with more favorable and specific indices of autonomic function in older adults," the researchers wrote. "Our results suggest potential mechanisms that might contribute to lower cardiovascular mortality with habitual PA later in life."

The researchers also found that older adults who engage in the highest levels of physical activity had about 11 percent reduced risks of heart attack or cardiac death than those with the lowest level of physical activity.

"Any physical activity is better than none, but maintaining or increasing your activity has added heart benefits as you age," Soares-Miranda told Newsday. "So if you feel comfortable with your usual physical activity, do not slow down as you get older - try to walk an extra block or walk at a faster pace."

The Centers for Disease Control and Prevention (CDC) says that about 720,000 individuals in the United States have a heart attack every year. More than 500,000 of these cases are first heart attacks. Heart disease is responsible for about one in four deaths in the U.S. per year.