Exercise Physiology Flashcards

Which energy system predominantly fuels a 400-meter sprint run?

Answer: Glycolytic (lactic acid) system

The 400-meter sprint (~45–60 seconds) relies primarily on fast glycolysis (lactic acid system) for ATP production.

During incremental exercise to exhaustion, blood lactate concentration begins to rise sharply at the lactate threshold because:

Answer: Lactate production exceeds clearance capacity

At the lactate threshold, fast-twitch fiber recruitment and accelerated glycolysis cause lactate production to exceed peripheral clearance.

Stroke volume typically reaches its plateau during upright cycle ergometry at approximately what percentage of VO2max?

Answer: 40–60%

Stroke volume plateaus at roughly 40–60% of VO2max during upright exercise, after which further cardiac output increases rely on heart rate.

The primary role of 2,3-bisphosphoglycerate (2,3-BPG) during prolonged exercise is to:

Answer: Facilitate oxygen release from hemoglobin to muscles

2,3-BPG binds to deoxyhemoglobin, reducing oxygen affinity and promoting O2 unloading in metabolically active tissues.

Which muscle fiber type has the highest oxidative capacity and fatigue resistance?

Answer: Type I

Type I (slow-twitch) fibers have the most mitochondria and oxidative enzymes, making them highly resistant to fatigue.

Excess post-exercise oxygen consumption (EPOC) is primarily attributed to which of the following?

Answer: Restoration of oxygen stores, removal of lactate, and elevated body temperature

EPOC reflects elevated metabolism needed to replenish oxygen stores, restore ATP-PCr, clear lactate, and return body temperature to baseline.

Which hormone primarily stimulates fat mobilization from adipose tissue during prolonged moderate-intensity exercise?

Answer: Epinephrine

Epinephrine activates hormone-sensitive lipase in adipocytes, dramatically increasing free fatty acid release during exercise.