Foundations of Exercise Science Flashcards

Which muscle fiber type has the highest oxidative capacity and is most resistant to fatigue?

Answer: Type I

Type I (slow-twitch) fibers have the highest mitochondrial density and oxidative enzyme activity, making them highly fatigue-resistant.

The sliding filament theory of muscle contraction states that sarcomere shortening occurs because:

Answer: Actin slides toward the center while myosin filaments remain stationary

In the sliding filament theory, thin actin filaments are pulled toward the M-line (center of the sarcomere) by myosin cross-bridges; neither filament changes length.

During maximal aerobic exercise, which cardiovascular adaptation most significantly increases cardiac output?

Answer: Both increased heart rate and stroke volume

Maximal cardiac output is achieved through simultaneous increases in both heart rate and stroke volume, with heart rate contributing more at very high intensities.

The Fick equation for oxygen consumption (VO2) is expressed as:

Answer: VO2 = HR × SV × (CaO2 − CvO2)

The Fick equation states VO2 = Cardiac Output × arteriovenous oxygen difference (a-vO2 diff), where cardiac output = HR × SV.

Which metabolic pathway is the PRIMARY energy source during a 400-meter sprint?

Answer: Glycolytic (lactic acid) system

A 400-meter sprint lasting ~45–60 seconds relies predominantly on anaerobic glycolysis, which produces ATP rapidly but also generates lactate.

Which hormone is primarily responsible for the acute regulation of blood glucose during prolonged aerobic exercise?

Answer: Glucagon

Glucagon rises during prolonged exercise to stimulate hepatic glycogenolysis and gluconeogenesis, maintaining blood glucose levels.

The respiratory exchange ratio (RER) value of 0.70 at rest indicates the body is primarily oxidizing:

Answer: Fats

An RER of 0.70 reflects fat oxidation, since fat metabolism produces 7 CO2 molecules for every 10 O2 consumed (CO2/O2 = 0.70).