Physical activity - 24/7 benefits
If you've heard it once, you've heard it a million times: physical activity is good for your heart. OK, so let us tell you something that maybe you don't know. Namely: how does physical activity improve heart health? Why do you need to be active for 30 minutes a day, most days of the week? How does physical activity affect cholesterol and lower blood pressure? True, the heart is a muscle that requires regular exercise, but that's just scratching the surface.
To truly understand how the body responds to activity, we need to go much deeper – right down to our cells and what happens to them when we move. When we are active, a lot of changes happen physically and chemically in our bodies, says Dr. Jim Rush, a Waterloo, Ont.-based Heart and Stroke Foundation researcher.
One of those important changes is an increase in blood flow. When we are active, our bodies require more oxygen and the heart must pump more blood to get that oxygen to every cell. That increased demand for blood creates a powerful impact, says Dr. Paula Harvey, a Toronto-based Heart and Stroke Foundation researcher. "Cells respond to the increased blood flow by signaling the body to produce more of a compound called nitric oxide."
Give cholesterol the slip
Nitric oxide, says Harvey, is a critical component in heart health because it helps prevent substances such as LDL (the bad cholesterol) from sticking to walls of the coronary arteries and forming plaque. Plaque build-up narrows the arteries and makes them stiffer – a condition known as atherosclerosis. Also, if plaque ruptures or breaks, a blood clot usually forms. The blood clot can block blood flow and result in a heart attack or stroke.
Bust high blood pressure
Nitric oxide also keeps cells on artery walls from becoming inflamed and increases their elasticity, allowing blood to flow more freely, a valuable tool in the fight to lower blood pressure. "Picture a straw opening up into the width of a garden hose," says Dr. Rush. "That's what happens when we are physically active for 30 minutes a day. Now imagine how much better blood flows when the passageway is more open." Even better, it takes hours for a garden hose to revert to a straw, and that means blood-pressure reduction that is sustained almost all day.
In fact, says Dr. Rush, most of the healthy changes in our bodies resulting from activity last a long time. The experts' best guess: up to 24 hours. "It's like taking a medication—the drug works for hours after you've swallowed the pill." That's why it's important to be physically active every day – so that you can keep your heart as healthy as possible. "People don't need to become marathon runners," says Dr. Harvey, who is physically active 60 minutes most days. "Even walking will make a huge difference and the payoff is tremendous."
Last reviewed April 2007.
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