For years now, research findings have indicated that an inactive lifestyle can lead to heart problems.  More recently, study data has highlighted the ill effects of overtraining.   Where on the spectrum of intensity is it best to exercise for protection against heart disease?

During last month's annual scientific conference of the American Heart Association, which is sponsored by the Council on Epidemiology and Prevention and the Council on Nutrition, Physical Activity and Metabolism, researchers presented findings that vigorous-intensity exercise is associated with a slightly greater protective effect against cardiovascular disease when compared to physical activities performed at a moderate-intensity.  The investigation was part of the on-going Health Professionals Follow-Up Study (HPFS) initiated in 1986 with the purpose of determining the relationship between health-related behaviors and the incidence of disease in men.  To determine the role of vigorous exercise in preventing cardiovascular disease, researchers examined data collected on 43, 646 men, ages 40-75 years, enrolled in HPFS from 1986-2006.

Beginning in 1986, the subjects' leisure-time physical activities were assessed every two years through a series of questions in regards to mode of physical activity performed and time spent per week exercising.  The investigators calculated the cumulative average of hours spent per week engaged in all types of vigorous activity (6+ METs - e.g., biking at a speed of approximately 10 miles per hour) and adjusted for all other activities that were less than 6 METS.  After controlling for age, risk factors associated with cardiovascular disease, and other activities performed, researchers found that men who engaged in 6.5 to 7.9 hours of vigorous physical activity per week had a lower risk for the development of cardiovascular disease than men who did not engage in any vigorous exercise.  They also noted that this protective effect was slightly attenuated in men who engaged in more than 7.9 hours of vigorous-intensity exercise per week.

The researchers caution, however, that this does not mean that previously sedentary individuals have to engage in vigorous-intensity exercise in order to get health benefits.  But, it does provide some insight for individuals who already engage in moderate-intensity exercise that if they increase their intensity, they will experience greater protective effects against cardiovascular disease.

Note:  Before beginning an exercise program or increasing the intensity level of a current routine, a physician's approval should be obtained, especially for older adults and those at risk for or who currently have chronic health conditions.

Resources:
Heartwire, "Vigorous Physical Activity Modestly More Protective Than Moderate Activity," O'Riordan, M.

Abstracts from the 2010 Joint Conference - Nutrition, Physical Activity and Metabolism and 50th Cardiovascular Disease Epidemiology and Prevention: "Physical Activity and Incident Cardiovascular Disease: Investigation of the Effect of High Amounts of Vigorous-Intensity Activity," Chomistek, A.K.