Various research organizations suggest specific amounts of weekly physical activity for losing and managing weight and improving health. A study published in Medicine & Science in Sports & Exercise (2011; 43 [10], 1884–90) says that men who do at least 3 hours of vigorous-intensity exercise per week can reduce myocardial infarction (MI) risk by as much as 22%.

The study involved 1,239 men who participated in the Health Professionals Follow-Up Study from 1994 to 2004. During that time frame, 412 men suffered an MI incident. The scientists then compared these men with 827 others who did not experience heart problems.

“From detailed responses to a modified Paffenbarger physical activity questionnaire, we determined the association between average hours of vigorous-intensity activity (activities requiring METS ≥ 6) and MI risk,” reported the study authors. “[The] inverse association [we found] can be partially explained by the beneficial effects of physical activity on HDL-C, vitamin D, apolipoprotein B, and hemoglobin A1c. Although the inverse association attributable to these biomarkers is substantial, future research should explore benefits of exercise beyond these biomarkers of risk.”