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2. 2 Your Heart, Lungs, and Circulation The word aerobic means “with oxygen.” Aerobic activities Continuous activity that requires large amounts of oxygen. Term to Know Done regularly, aerobic activity strengthens the heart and the lungs.

3. 3 Your Circulatory System To understand how aerobic activities work, you need to have some knowledge of the circulatory system, also called the cardiovascular system. Circulatory system Consists of the heart, blood, and blood vessels. Term to Know This system is responsible for circulating blood throughout the body.

4. 4 Your Circulatory System When at rest, the heart beats an average of 72 times per minute. Stroke volume The amount of blood pumped per beat of the heart. Term to Know Your heart rate and stroke volume increase during strenuous physical activity.

5. 5 Your Circulatory System The oxygen that your blood carries is introduced into your body by means of your respiratory system. Respiratory system The body system that exchanges gases between your body and the environment. Term to Know

6. 6 Your Circulatory System The principal organ of your respiratory system is your lungs. Your lungs exchange oxygen and carbon dioxide through the process of respiration.

7. 7 Your Circulatory System Unlike the heart, the lungs are not a muscle. Diaphragm A muscle found between the chest cavity and abdomen. Term to Know Rather, they get their power from the diaphragm, the intercostal muscles around the ribs, and the abdominal muscles in the lower stomach area.

8. 8 Your Circulatory System Benefits of Aerobic Activity Strengthens the body Increases stroke volume Lowers your resting heart rate Conditions the muscles used in breathing Results in more effective delivery of oxygen

9. 9 Your Circulatory System One long-term result of regular physical activity is cardiorespiratory endurance. Cardiorespiratory endurance The ability of the body to work continuously for extended periods of time. Term to Know

10. 10 Aerobic vs. Anaerobic Physical Activities Aerobic activity must occur over a sustained period of time; anaerobic activity works differently. Anaerobic activity Activity that requires high levels of energy and is done for only a few seconds or minutes at a high level of intensity. Term to Know

11. 11 Aerobic vs. Anaerobic Physical Activities Anaerobic means “without oxygen.” The energy produced in anaerobic activities does not depend on oxygen.

12. 12 Aerobic vs. Anaerobic Physical Activities Participation in anaerobic activities leads to anaerobic fitness. anaerobic fitness Higher levels of muscular strength, muscular endurance, and flexibility. Term to Know

13. 13 Aerobic vs. Anaerobic Physical Activities Anaerobic activities require large amounts of energy, a requirement that your body cannot meet for very long. This is because your heart cannot supply enough oxygen-rich blood to your tissues and organs to meet the high demand.

14. 14 Aerobic vs. Anaerobic Physical Activities When you can meet your energy needs by supplying large amounts of oxygen to your body, you are working primarily in an aerobic mode. If you cannot meet the oxygen demands of a high-intensity physical activity, your body is more conditioned to working anaerobically.

15. 15 Aerobic vs. Anaerobic Physical Activities Interval training can allow you to work aerobically and anaerobically in the same workout. Interval training A program in which high-intensity physical activities alternate with low- intensity recovery bouts for several minutes at a time. Term to Know