Exercise Physiology Flashcards

Which energy system is the PRIMARY source for a 400-meter sprint?

Answer: Glycolytic system

The 400-meter sprint (approximately 45–60 seconds) relies primarily on the glycolytic (anaerobic lactic) system.

During prolonged aerobic exercise, which fuel source becomes increasingly important as glycogen stores deplete?

Answer: Free fatty acids

As muscle glycogen decreases during prolonged exercise, free fatty acid oxidation progressively contributes more to energy production.

What is the approximate oxygen uptake at rest (1 MET) for the average adult?

Answer: 3.5 ml/kg/min

One MET equals approximately 3.5 ml/kg/min of oxygen consumption, the standard resting metabolic rate.

Which cardiac parameter is defined as the volume of blood ejected per heartbeat?

Answer: Stroke volume

Stroke volume is the amount of blood pumped by the left ventricle with each contraction.

The Fick equation states that VO2 = cardiac output × which variable?

Answer: Arteriovenous oxygen difference

The Fick principle expresses VO2 as the product of cardiac output and the a-vO2 difference (oxygen extracted by tissues).

During maximal aerobic exercise, which factor is most responsible for limiting VO2max in healthy, untrained individuals?

Answer: Maximal cardiac output

In healthy untrained individuals, maximal cardiac output (heart rate × stroke volume) is the primary limiting factor for VO2max.

What physiological change explains why trained endurance athletes have lower resting heart rates than untrained individuals?

Answer: Increased stroke volume (cardiac hypertrophy)

Endurance training causes cardiac hypertrophy and increased stroke volume, allowing the heart to maintain cardiac output at a lower heart rate.