How Exercise Makes the Heart Stronger

For you, physical activity might be a means to lose weight, or even to improve your mood, but the truth is it does so much more. Exercising your body exercises your heart.

“Your heart muscle itself doesn’t get stronger,” says Nieca Goldberg, MD, medical director of the Joan H. Tisch Center for Women's Health at NYU Langone Medical Center, “but the physiology around it improves the function of the heart by making it more efficient and your blood vessels more flexible.” In addition, the greater flexibility of the blood vessels make them more resistant to the buildup of plaque—a known contributor to heart disease.

“During exercise your heart rate and blood pressure increase to deliver blood to your exercising muscles, and your blood vessels respond by enlarging to supply blood flow to your exercising muscles.” Over time your baseline heart rate slows down because of this “training effect,” Dr. Goldberg explains. “Exercise lowers heart rate and blood pressure, which enables you to exercise longer before you get tired because your heart is working more efficiently.” Each heart beat delivers a greater volume of blood to your exercising muscles so your heart doesn’t have to work as hard.

The blood pressure effect may last even when you’re not working out. Regular exercise helps keep arteries elastic (flexible), says Victoria Shin, MD, cardiologist with Torrance Memorial Medical Center, Torrance, CA. “This, in turn, ensures good blood flow and normal blood pressure.” Exercise can lower your systolic blood pressure (the top number in a blood pressure reading) by an average of 4 to 9 mm of mercury (mm Hg), Shin adds, which is as effective as some blood pressure medications.

For some people with high blood pressure, exercise alone is enough to reduce the need for medication, Shin adds. "If your blood pressure is already well controlled—less than 120/80 mm Hg—exercise can help prevent it from rising as you age, as the arteries naturally get stiffer." This is not a one and done deal, however. Keeping your blood pressure low requires regular exercise. “It takes about one to three months for regular exercise to have an impact on your blood pressure,” says Shin. “The benefits last only as long as you continue to exercise.”

Exercise may also make the heart’s 24/7 job easier by helping lower cholesterol, or the fats found in blood. The exact way exercise does this is unclear, but experts believe it enhances muscles' ability to utilize fats, as opposed to glycogen (aka stored carbohydrate), thus reducing circulating cholesterol, says Shin.

“Exercise has also been shown to increase levels of enzymes that clear bad cholesterol from the blood.” Specifically, exercise has been linked to a consistent increase in HDL (good cholesterol) with moderate decreases in triglycerides and LDL (bad cholesterol).

This could be why the American Heart Association recommends that adults perform moderately intense exercise for a minimum of 30 minutes a day at least 5 days a week, for a total of 150 minutes per week. And it isn’t like you only need to run to satisfy this recommendation and get heart health benefits; various types of aerobic exercise help your heart in different ways.