Answer to Question 1
Cardiorespiratory conditioning occurs as aerobic workouts improve heart and lung function. Cardiac output increases, thus enhancing oxygen delivery. The heart becomes stronger, and each beat pumps more blood. Because the heart pumps more blood with each beat, fewer beats are necessary, and the resting heart rate slows down. The average resting pulse rate for adults is around 70 beats per minute, but people who achieve cardiorespiratory conditioning may have resting pulse rates of 50 or even lower. The muscles that work the lungs also become stronger, so breathing becomes more efficient. Circulation through the arteries and veins improves. Blood moves easily, and blood pressure falls. In short, cardiorespiratory conditioning increases cardiac output and oxygen delivery, increases blood volume per heart beat (stroke volume), slows resting pulse rate, increases breathing efficiency, improves circulation, and reduces blood pressure.
Cardiorespiratory endurance reflects the health of the heart and circulatory system, on which all other body systems depend. To improve your cardiorespiratory endurance, activities must be sustained for 20 minutes or longer and use most of the large muscle groups of the body (legs, buttocks, and abdomen). The level of training must be intense enough to elevate your heart rate. A person's own perceived effort is usually a reliable indicator of the intensity of an activity. In general, workouts should be at an intensity that raises your heart rate but still leaves you able to talk comfortably. For those who are more competitive and want to work to their limits on some days, a treadmill test can reveal the maximum heart rate. Workouts are safe at up to 85 percent of that rate.
One of the benefits of cardiorespiratory training is that fit muscles use oxygen efficiently, reducing the heart's workload. An added bonus is that muscles that use oxygen efficiently can burn fat longera plus for body composition and weight control.
Answer to Question 2
a