Exercise Science & Application Flashcards

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

Answer: Glycolytic system

The glycolytic system dominates efforts lasting roughly 30–120 seconds, such as a 400-meter sprint.

The sliding filament theory describes how muscle contraction occurs when:

Answer: Myosin heads pull actin filaments toward the M-line

Cross-bridges form when myosin heads attach to actin and pull actin toward the center of the sarcomere (M-line), shortening the muscle.

Which of the following BEST describes the Fick equation for oxygen consumption?

Answer: VO2 = HR × SV × (a-vO2 difference)

The Fick equation states VO2 = cardiac output (HR × SV) multiplied by the arteriovenous oxygen difference.

A client's respiratory exchange ratio (RER) is 0.85. This MOST likely indicates they are primarily using:

Answer: An equal mix of carbohydrate and fat

An RER of 0.85 falls between the pure-fat value (~0.70) and pure-carbohydrate value (1.00), indicating a mixed substrate blend.

Which muscle action occurs when the biceps brachii lengthens while producing force during the lowering phase of a curl?

Answer: Eccentric

Eccentric contractions occur when a muscle produces force while lengthening, as when controlling the lowering of a weight.

During high-intensity exercise, lactate threshold is BEST defined as the exercise intensity at which:

Answer: Blood lactate begins to accumulate faster than it can be cleared

Lactate threshold marks the point where lactate production exceeds clearance, causing blood lactate to rise exponentially.

Type II muscle fibers differ from Type I fibers in that they have:

Answer: Higher myosin ATPase activity and faster contraction speed

Type II (fast-twitch) fibers have higher myosin ATPase activity, enabling faster cross-bridge cycling and rapid force production.