Exercise Physiology Questions and Answers

Answer: A

The adaptive response is increasing intramuscular lipid use during exercise.

Endurance training increases the number and size of mitochondria and the activity of fat-oxidising enzymes in the trained muscles. As a result, the muscles burn more fat, including the triglyceride stored within the muscle fibres, at a given submaximal workload.

This spares carbohydrate, so muscle glycogen use during exercise falls rather than rises. Trained muscles also store more, not less, intramuscular lipid, and the change in liver glycogen content is not the characteristic adaptation the stem describes.

Answer: B

Statement (I) is false and (II) is true.

Expiration is the movement of air out of the lungs; the movement of air into the lungs is inspiration, so statement I is false.

At rest, expiration is passive: when the diaphragm and external intercostal muscles relax, the elastic recoil of the lungs and chest wall reduces the volume of the thorax and pushes air out. Only in exercise or forced breathing do the abdominal and internal intercostal muscles make expiration active. So statement II is true.

Answer: A

The actual exchange of gases in the lungs takes place in the alveoli.

The alveoli are tiny air sacs at the ends of the bronchioles, about 300 million of them, with walls only one cell thick and surrounded by capillaries. Oxygen diffuses from the alveolar air into the blood and carbon dioxide diffuses out, across a very large surface area.

The trachea, pharynx and primary bronchi are conducting airways that only carry air to and from the alveoli; their walls are too thick for gas exchange.

Answer: A

The key matches (1) with (ii), (2) with (iii) and (3) with (i), so the answer is 1-ii, 2-iii, 3-i.

The plank hold is a static hold in which the muscles stay tense and do not change length (an isometric contraction), which is the only list-II item that fits the 'passive' (non-moving) contraction. Pull-ups are an active, dynamic exercise in which the muscles shorten and lengthen against body weight. The treadmill is matched to the isokinetic item, the constant-speed type of work.

The other codes each break one of these ideas: 1-i, 2-iii, 3-ii puts the static plank hold against isokinetic work; 1-iii, 2-ii, 3-i calls the pull-up the passive item; and 1-ii, 2-i, 3-iii calls the pull-up isokinetic, although the speed of a pull-up changes freely.

Check on the key: the labels 'passive muscle contraction' and 'isokinetic' for these exercises are the key's own reading and could not be confirmed in a standard reference, but this is the only code that places the plank hold with the static contraction and the pull-up with the active one.

Answer: C

Supercompensation means adaptation to load.

A training load first causes fatigue and a temporary drop in performance capacity. During recovery the body not only restores its energy stores and repairs tissue, it overshoots its previous level; this rise above the starting point is supercompensation. If the next load comes at the right time, during this phase, performance improves progressively, which is the basis of planning training and recovery.

Fatigue is the first phase of the cycle, not the adaptation. 'Second wind' is the sudden relief felt during prolonged exercise, and oxygen debt is the extra oxygen consumed after exercise.

Answer: C

The key's answer is participating muscle receive efferent signals from the brain.

Catching is a motor action. The eyes and other senses send information about the approaching ball to the brain along afferent (sensory) pathways; the brain processes it, times the catch, and sends efferent (motor) signals to the muscles of the hand, which then close at the right moment. The grasp itself happens because the muscles receive those efferent commands.

Option D is wrong because afferent signals carry information to the brain, not instructions to the hand. Alpha brain waves and the parasympathetic nervous system have nothing to do with the timing of a grasp.

Answer: C

The connective tissue around each muscle fibre is the endomysium.

Skeletal muscle is wrapped in three layers of connective tissue. The endomysium surrounds each individual muscle fibre (cell). The perimysium wraps bundles of fibres, called fascicles, and the epimysium encloses the whole muscle and continues into the tendon.

Myofibrils are not connective tissue at all; they are the contractile threads inside each muscle fibre, made of actin and myosin filaments.

Answer: B

The phenomenon is the all or none law.

An individual muscle fibre, like a nerve fibre, either responds fully to a stimulus or not at all. Once the stimulus reaches the threshold, the fibre contracts to its maximum for the conditions, and a stronger stimulus does not make that single fibre contract harder.

A whole muscle can still produce graded force, because the nervous system varies the number of motor units recruited and the frequency of their firing. 'All or one', 'all law except one' and 'none law except one' are distortions of the name.

Answer: B

The point is called the anaerobic threshold.

As exercise intensity and oxygen consumption rise, there comes a point where the energy demand can no longer be met aerobically alone. Anaerobic glycolysis speeds up, lactate is produced faster than it can be removed, and blood lactate and ventilation rise sharply. That intensity is the anaerobic threshold, an important marker for endurance training.

The aerobic threshold is a lower intensity, where lactate first begins to rise above resting levels. The lactate threshold is closely related but named after the measurement rather than the process the question describes, and 'metabolic threshold' is not the standard term.

Answer: D

The muscles are the scalenes.

The anterior, middle and posterior scalene muscles run from the transverse processes of the cervical vertebrae down to the first and second ribs. When they contract they lift these ribs, helping to expand the upper chest during inspiration, especially in deep breathing.

The sternocleidomastoid is also an accessory muscle of inspiration, but it raises the sternum and clavicle rather than the first two ribs. The trapezius moves the shoulder girdle, and the back extensors straighten the spine.