The activities that best improve these systems are the ones that get your heart and lungs working harder - at a steady rate for at least 20 minutes. Activities like cross-country skiing, running, skating, cycling, rowing, brisk walking and swimming, all get the heart, lungs and blood vessels working to deliver the needed oxygen to the working muscles. The most important improvement is to the heart muscle, which becomes stronger and, therefore, is able to pump more blood with each heartbeat. The amount of oxygen your body can deliver to the active muscles is called your aerobic capacity, which has a direct effect on your body's energy activity you enjoy and keep at it for a minimum of 20 minutes on a daily basis. Your heart will thank you for it.
Life is like riding a bicycle.
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