How Is the Cardiovascular System Affected by Exercise?
Exercise has immediate and long-term effects on the cardiovascular system. While all types of exercise provide health and fitness benefits, strength training and stretching have a minimal impact on the cardiovascular system. Aptly called cardio exercise, activities such as walking, running, biking and swimming activate the heart and lungs; when done routinely, they create enduring changes in your physiology.
Energy Demands of Cardio Exercise
When you exert the large, powerful muscles in your lower body for more than a few minutes, you create energy demands that increase your heart rate and respiration. During cardio, you repeatedly contract and relax your gluteal, hamstring and quadriceps muscles. You quickly deplete the 30 seconds' worth of fuel, a molecule called ATP, your muscles have on hand. Your muscles resort to glucose in your blood and a sugar, glycogen, stored in your muscles for raw material to make more ATP. Within a few minutes, your blood glucose levels start to dip, causing your pancreas to release a hormone, glucagon. Delivered through your bloodstream to tissues throughout your body, glucagon triggers the release of glycogen stored in your liver and triglycerides, or fat, stored in fat cells under your skin and in your abdomen.
Immediate Effects of Cardio
As your muscles burn fuel to power movement, nerves in your arteries detect a rise in carbon dioxide, a waste product produced by energy metabolism. This triggers your brain to increase your heart and respiration rate. Your lungs inhale more deeply to get oxygen needed for burning carbohydrates, and you exhale more strongly to expel the carbon dioxide. Meanwhile, your heart rate increases to deliver fuel and oxygen to your muscles and to transport carbon dioxide, lactic acid and other waste products away. To handle the increased blood flow, your arteries, veins and capillaries dilate.
When you do moderately intense cardio for 30 to 60 minutes a day at least three or four times a week, you give your lower body muscles a workout and you also improve your cardiovascular and respiratory fitness. You strengthen the cardiac muscle that surrounds your heart. The walls of your heart become thicker and stronger, and you pump a greater volume of blood with each stroke. Consequently, your resting heart rate decreases. You develop more red blood cells, improving your ability to transport oxygen to your muscles. The capillaries that surround the alveoli in your lungs get wider and develop more branches, improving your capacity to exchange carbon dioxide and oxygen in your lungs. Improvements in circulation and oxygen delivery reduce the amount of lactic acid that accumulates during exercise. Because of the increased blood volume pumped through the cardiovascular system during cardio exercise, the walls of your arteries improve in elasticity.
Improvements in cardiovascular fitness contribute directly to several long-term health benefits, including a reduction in risk of coronary artery disease, according to "Postgraduate Medicine." Other health benefits include a lower risk for obesity, diabetes, gallbladder disease and certain types of cancer, reports ABC News.
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