A well-trained, 20-year-old track star is in excellent health and has often run

Question

A well-trained, 20-year-old track star is in excellent health and has often run a mile in under 4 minutes. As a part of a large group study of young athleates engaged in endurance sports, he enters the exercise laboratoy for evaluation of his physical condition during treadmill excercise. In antixipation of a race, the runners sympathetic nervous system is activated, tramsits command, and adrenaline hormones are released from the adrenal gland. This results in cardiac drift, more forceful myocardial contractility, increased cardiac output, peripheral increase in blood volume, and increase in blood pressure. Also there would be an initial increase in heart rate. As the treadmill is speeded up, what happens to the heart rate, peripheral resistance, skin blood flow, cardiac output and blood flow distribution? What happens to stroke volume and pressure? Heart rate continues to ______, until the rate reaches a plateau of about ______ beats per minute at maximum effort. Peripheral resistance ______ because of relaxation of ______ in active muscle and skin (as body ______ rises). Skin blood flow ______ which aids in heat ______. Blood flow to inactive muscle, ______ and gastrointestinal tract is ______. The primary form of heat dissipation is ______. In the trained athlete, ______ volume is large at rest and ______ furter with exercise, whereas in the untrained individual, stroke volume shows little ______ and ______ increases greatly. The actual cause of the ______ in cardiac output is the decrease in peripheral ______. Mean arterial blood _____ increases slightly, as does pulse pressure (i.e., ______ pressure increase a little more than ______ does pressure). Cardiac output is also supported by increased venous ______ cavilitated in part my muscle compression of the leg veins with one-way valves.

Explanation / Answer

1.Increases
2.180 beats/min
3.Decreases
4.Arterioles
5.Temperature
6.Increases
7.Loss
8.Kidney
9.Reduced
10.Increase
11.Stroke volume
12.Increases
13.Change
14.Heartbeat
15.Increases
16.Peripheral Resistance
17.Blood pressure
18.Systolic pressure
19.Diastolic pressure
20.Blood

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