Cardiac Output “So you want to be a marathoner?”

Do you have the blood for it?

“Q” In The Untrained Person In the average person, a 5-L cardiac output is usually sustained with a heart rate of approximately 70 beats a minute. In the average person, a 5-L cardiac output is usually sustained with a heart rate of approximately 70 beats a minute. Stroke volume and cardiac output for women usually average approximately 25% below the values for men. Stroke volume and cardiac output for women usually average approximately 25% below the values for men. This “gender difference” is essentially due to the smaller body size of the average women. This “gender difference” is essentially due to the smaller body size of the average women. Stroke volume is about 70ml at rest. Stroke volume is about 70ml at rest.

“Q” In The Endurance Athlete Endurance training causes the sinus node in the heart to come under greater control from the parasympathetic nervous system. Endurance training causes the sinus node in the heart to come under greater control from the parasympathetic nervous system. At the same time there is probably a reduction in the sympathetic activity. At the same time there is probably a reduction in the sympathetic activity. When the heart slows due to the parasympathetic influence, this is called “vagal” tone. When the heart slows due to the parasympathetic influence, this is called “vagal” tone. Stroke volume may be 100ml at rest for the athlete. Stroke volume may be 100ml at rest for the athlete.

Heart Rate During Exercise The large stroke volume of an endurance athlete is accompanied by a heart rate reduction during submaximal exercise. The large stroke volume of an endurance athlete is accompanied by a heart rate reduction during submaximal exercise.

Distribution of Cardiac Output At rest: approximately 1/5 of blood flow is directed toward muscle tissue. At rest: approximately 1/5 of blood flow is directed toward muscle tissue. The majority of blood is directed to the digestive tract,liver,spleen,brain and kidneys. The majority of blood is directed to the digestive tract,liver,spleen,brain and kidneys. During exercise: the major portion of the cardiac output is diverted to working muscles. During exercise: the major portion of the cardiac output is diverted to working muscles. Some tissues can handle a temporary reduction in blood during heavy exercise. Some tissues can handle a temporary reduction in blood during heavy exercise. Example:blood flow to skin increases with light/medium exercise but decreases with heavy exercise. Example:blood flow to skin increases with light/medium exercise but decreases with heavy exercise.

Blood Flow to the Heart and Brain Some tissues cannot compromise their blood flow. Some tissues cannot compromise their blood flow. The myocardium uses about 75% of the oxygen flowing through the coronary vessels at rest. The myocardium uses about 75% of the oxygen flowing through the coronary vessels at rest. A large increase in heart rate during exercise, is accompanied by an increase in coronary circulation. A large increase in heart rate during exercise, is accompanied by an increase in coronary circulation. This increase is up to 1 liter of blood per minute. This increase is up to 1 liter of blood per minute. Cerebral blood flow is also increased by up 30% compared to resting conditions. Cerebral blood flow is also increased by up 30% compared to resting conditions.

Extraction of Oxygen: A-V 02 Difference At rest: about 75% of the blood’s original oxygen load is still bound to hemoglobin after it makes the complete tour through the body. At rest: about 75% of the blood’s original oxygen load is still bound to hemoglobin after it makes the complete tour through the body. After training: up to 85% of the oxygen is removed from the hemoglobin during exercise. After training: up to 85% of the oxygen is removed from the hemoglobin during exercise. But only in the specific muscle fibers used during exercise. But only in the specific muscle fibers used during exercise. This is due to increased capillaries, mitochondria and aerobic enzymes. This is due to increased capillaries, mitochondria and aerobic enzymes.

Cardiovascular Adjustments to Upper Body Exercise Maximal oxygen uptake during exercise with the arms is generally 20-30% lower than exercise with the legs. Maximal oxygen uptake during exercise with the arms is generally 20-30% lower than exercise with the legs. Maximal heart rate is also much lower with arm work. Maximal heart rate is also much lower with arm work. What is the reason ? What is the reason ? Relatively smaller muscle mass involved. Relatively smaller muscle mass involved.

The Athlete’s Heart Cardiac hypertrophy results from individual myofibrils thickening and from an increased number of myofibrils. Cardiac hypertrophy results from individual myofibrils thickening and from an increased number of myofibrils. This is viewed as a fundamental adaptation to an increased work load. This is viewed as a fundamental adaptation to an increased work load. In endurance athletes the heart may be up to 25% larger. In endurance athletes the heart may be up to 25% larger. Not sure if this is genetic endowment or training induced or both. Not sure if this is genetic endowment or training induced or both.

Shot Putter vs Runner “Isometric” athletes like wrestler, lifters have larger muscle mass, especially the intraventricular septum. “Isometric” athletes like wrestler, lifters have larger muscle mass, especially the intraventricular septum. Lifters heart may weigh 330grams and have left ventricular volume of 110ml. Lifters heart may weigh 330grams and have left ventricular volume of 110ml. Runners heart may weigh 308 grams and have left ventricular volume of 180ml. Runners heart may weigh 308 grams and have left ventricular volume of 180ml. Non-athletic heart weighs 211 grams and has left ventricular volume of 101ml. Non-athletic heart weighs 211 grams and has left ventricular volume of 101ml.