How Does Exercise Affect Your Heart?

Cardiovascular exercise involves the use of large muscles in a repetitive fashion, activating muscle fibers programmed for endurance and utilizing a heart rate range anywhere from 40 to 85 percent of your maximum heart rate. Think: running, jogging, swimming, biking, or spinning.

How does cardiovascular exercise affect your heart?

When performing cardio, blood flow is directed toward working muscles and away from areas that aren't doing much (such as your arms during running, or the digestive tract). There is increased blood flow, and blood volume returning to the heart.

As the heart registers a larger blood volume, over time the left ventricle adapts and enlarges. This larger cavity can hold more blood, and ejects more blood per beat, even at rest.

Over time, with chronic cardio training, our resting heart rate drops because each beat delivers a bigger burst of blood, and fewer beats are needed. This takes work off your heart and is why cardio exercise is recommended for heart health.

However, cardiovascular exercise can also produce stress. If we get into over-training, we may hit a point where we are drowning in cortisol. This eventually leads to immune-suppression and fat gain around the abdomen and face.

People who spend a significant part of their day in stress, who have poor digestion or other sources of physiological stress, should not further their stress levels by overtraining. Always think of your goals, moderate your exercise if necessary, and work to reduce your stress levels.

How does strength training exercise affect your heart?

Strength training exercise works the heart in a completely different way. At any given moment, certain muscles are contracting and relying predominantly on type two muscle fibers, which are responsible for giving us a great looking body and making us stronger.

As the muscles contract—say the arm muscles during a bicep curl—they press and close the blood vessels that flow through them. This leads to increased blood pressure in the rest of the body and the heart has to fight against a stronger force to push blood out.

The heart adapts to this by increasing the thickness of the left ventricle wall. This thickness derived from chronic weight training is healthy, whereas the thickness from chronic high blood pressure is not.

What's the difference? The healthy heart only has to work under pressure for two to three hours of strength training per week, whereas the heart with high blood pressure has to work 24 hours a day, seven days a week. The second heart may exhaust, whereas the healthy heart becomes stronger with a lower resting heart rate.

Exercise also stimulates the production of new blood vessels. As we make more blood vessels, there are more places for blood to flow, which results in more efficient circulation. Cardiovascular exercise increases the number of new blood vessels while resistance training increases the size of those blood vessels.

Stick to a smart, well-designed exercise program and pay special attention to your diet. Practice healthy eating and stress-reduction techniques. Exercise can naturally lower blood pressure to normal limits when combined with stress reduction and an effective dietary approach.

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Erica Robinson is a student at the Canadian College of Naturopathic Medicine.


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