ACE Exercise Physiology 3

Question 1

A client's resting heart rate decreases after 12 weeks of aerobic training. This is primarily due to:

Accepted Answer

Increased parasympathetic nervous system tone

Answer

Aerobic training enhances vagal (parasympathetic) tone, which slows the sinoatrial node and lowers resting heart rate, often called 'athlete's bradycardia.'

Question 2

Which type of muscle contraction produces the GREATEST amount of force?

Accepted Answer

Eccentric contraction

Answer

Eccentric (lengthening) contractions generate the greatest force because both active cross-bridge cycling and passive elastic elements (titin) resist the stretch.

Question 3

Which physiological variable best predicts aerobic exercise performance in trained athletes?

Accepted Answer

Lactate threshold as a percentage of VO2 max

Answer

While VO2 max sets the ceiling, the lactate threshold expressed as a percentage of VO2 max is a superior predictor of endurance performance because it reflects sustainable exercise intensity.

Question 4

What is the primary role of the enzyme creatine kinase (CK) during high-intensity exercise?

Accepted Answer

Catalyzes the transfer of a phosphate from phosphocreatine to ADP to regenerate ATP

Answer

Creatine kinase catalyzes the reaction PCr + ADP → Cr + ATP, rapidly regenerating ATP from the phosphocreatine store during short, high-intensity bursts of activity.

Question 5

Which of the following occurs in fast-twitch (Type II) muscle fibers compared to slow-twitch (Type I) fibers?

Accepted Answer

Faster myosin ATPase activity

Answer

Type II fibers have faster myosin ATPase, allowing rapid cross-bridge cycling and high force production, but they fatigue more quickly due to lower oxidative capacity.

ACE - Personal Trainer Exam Practice Test

ACE - Personal Trainer Exam Practice Test

ACE Exercise Physiology 3