What are the two general categories of muscle fibers?

• Fast twitch and slow twitch

• Fast-twitch and slow-twitch

• White and red

• Aerobic and anaerobic

What determines the oxidative capacity of a muscle fiber?

• Amount of actin

• Number of mitochondria, capillaries, and myoglobin

• Glycogen stores

• Rate of cross-bridge cycling

Which type of muscle fiber is more efficient in producing ATP aerobically?

• Type IIa

• Type IIx

• Type I

• Fast-twitch fibers

What property allows Type IIx fibers to generate high force rapidly?

• High capillary density

• High ATPase activity

• Low myoglobin content

• High mitochondrial density

What is the primary energy source for muscle activity lasting less than 10 seconds?

• Glycogen stores

• Lactic acid system

• Aerobic metabolism

• Phosphocreatine system

What is the role of myoglobin in muscle fibers?

• Facilitates glycolysis

• Transports calcium

• Stores oxygen in muscle cells

• Provides structural support

Which phase of muscle contraction involves the release of calcium from the sarcoplasmic reticulum?

• Relaxation phase

• Latent period

• Contraction phase

• Fatigue phase

Which type of muscle fiber is primarily recruited for long-term endurance performance?

• Type IIa

• Type I

• Type IIx

• Fast-twitch fibers

What process occurs when a single action potential triggers a muscle contraction?

• Tetanus

• Twitch

• Summation

• Isometric contraction

What is specific tension in muscle fibers?

• Force produced per motor unit

• Force produced per cross-sectional area

• Total contractile strength

• Degree of fatigue