Doctors have known for years that exercise helps prevent heart attacks, and the reasons for this benefit are fairly well-understood. Exercise increases blood flow, strengthens the heart, improves the circulatory system, and reduces the likelihood of arterial blockage.
What hasn't been as well understood is the protection that exercise provides for individuals who suffer a heart attack. Recent research from Emory University School of Medicine may have discovered why this protection occurs.
The Research and Results
Researchers led by Dr. John Calvert, assistant professor of surgery and Dr. David Lefer, professor of surgery, used mice to investigate the effects of exercise on the heart. They found that when they provided mice with an exercise wheel for four weeks, three things were achieved: mice were protected from coronary heart blockage, mice that experienced heart attacks showed less damage and mice were protected in these ways a week after stopping their exercise program.
When Calvert and Lefer ran tests, they discovered that the mice's exercise increased endothelial nitric oxide synthase (eNOS), an enzyme that boosts nitric oxide. Nitric oxide is a short-lived gas produced in the body that can help dilate blood vessels and increase blood flow, factors that can increase survival during a heart attack. While the body can't store nitric oxide, it appears that nitric oxide can be stored as more stable chemicals, nitrite and nitrosothiols.
The boost in eNOS appears to enable the body to convert nitrite and nitrosothiols into nitric oxide in the event of an emergency, like a heart attack. The mice that exercised regularly had increased levels of all four of these chemicals in the heart and blood tissue. The mice also maintained an increase in heart protection four weeks after they stopped exercising, the same point at which these chemical levels returned to baseline.
While this study was only performed on mice, you can assume that similar protection occurs in humans. More research needs to be done, but there's no reason to wait for definitive research to start an exercise program.
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Laura Williams writes about exercise and fitness for Exercise.com through her regular column "Exercise Science". She is currently completing her master's in Exercise Science.