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Question 1Exercise Sciences (scientific foundations)

A maximal-effort sprint lasting approximately 6 seconds relies predominantly on which energy system?

  1. Oxidative phosphorylation
  2. ATP-PC system Correct answer.
  3. Aerobic glycolysis
  4. Fast glycolysis

Explanation

Maximal efforts of roughly 6 seconds or less are powered mainly by stored ATP and phosphocreatine, which resynthesize ATP at the fastest rate of any system. The contribution of glycolysis and oxidative metabolism grows as the effort lengthens, but neither can match the phosphagen system's rate of ATP supply.

Question 2Exercise Sciences (scientific foundations)

Compared with Type I fibers, Type IIx fibers are characterized by which of the following?

  1. Higher myosin ATPase and glycolytic enzyme activity Correct answer.
  2. Slower contraction velocity and greater fatigue resistance
  3. Greater capillary density and higher mitochondrial volume
  4. Lower peak force per unit of cross-sectional area

Explanation

Type IIx fibers are fast-twitch, glycolytic fibers with high myosin ATPase activity and abundant glycolytic enzymes, supporting rapid and powerful contractions. Their oxidative capacity and fatigue resistance are low relative to Type I fibers.

Question 3Exercise Sciences (scientific foundations)

Which muscle group is the primary agonist for knee extension?

  1. Tibialis anterior muscle
  2. Quadriceps femoris Correct answer.
  3. Hamstrings
  4. Gastrocnemius

Explanation

The quadriceps femoris crosses the anterior knee and extends the tibia at the knee joint, making it the prime mover for knee extension. The other muscles listed act primarily at the hip, ankle, or opposite side of the knee.

Question 4Exercise Sciences (scientific foundations)

Stroke volume is best defined as which of the following?

  1. Blood ejected by the heart in one minute
  2. Volume of blood remaining after contraction
  3. The fraction of end-diastolic volume ejected
  4. Blood ejected by the left ventricle per beat Correct answer.

Explanation

Stroke volume is the quantity of blood ejected by one ventricle during a single contraction. Cardiac output is the product of stroke volume and heart rate, and ejection fraction expresses stroke volume as a percentage of end-diastolic volume.

Question 5Exercise Sciences (scientific foundations)

Torque is calculated as the product of force and which of the following?

  1. Angular velocity
  2. Linear momentum
  3. Moment arm Correct answer.
  4. Moment of inertia

Explanation

Torque is the rotational effect of a force and equals force multiplied by the perpendicular distance from the axis of rotation to the force's line of action, called the moment arm. Changing joint angle alters the moment arm and therefore the torque produced by the same muscle force.

Question 6Exercise Sciences (scientific foundations)

Which hormone is released from the posterior pituitary gland and increases water reabsorption by the kidneys?

  1. Atrial natriuretic peptide
  2. Aldosterone
  3. Cortisol
  4. Antidiuretic hormone Correct answer.

Explanation

Antidiuretic hormone, also called vasopressin, is released from the posterior pituitary and increases water reabsorption in the kidney collecting ducts, reducing urine output. Its secretion rises when plasma osmolality increases or blood volume falls.

Question 7Exercise Sciences (scientific foundations)

Which neurotransmitter is released at the neuromuscular junction to depolarize the muscle fiber?

  1. Dopamine
  2. Norepinephrine
  3. GABA
  4. Acetylcholine Correct answer.

Explanation

The alpha motor neuron releases acetylcholine into the synaptic cleft, where it binds nicotinic receptors on the motor end plate and triggers the end-plate potential that leads to muscle contraction. Acetylcholinesterase then breaks down the transmitter to terminate the signal.

Question 8Exercise Sciences (scientific foundations)

Which macronutrient provides the most energy per gram?

  1. Alcohol
  2. Fat Correct answer.
  3. Carbohydrate
  4. Protein

Explanation

Fat yields approximately 9 kcal per gram, whereas carbohydrate and protein each yield about 4 kcal per gram and alcohol yields about 7 kcal per gram. Fat's high energy density reflects its highly reduced, anhydrous chemical structure.

Question 9Exercise Sciences (scientific foundations)

In addition to ATP, the glycolysis of one glucose molecule yields which of the following?

  1. Two FADH2 molecules
  2. Two acetyl-CoA molecules
  3. One molecule of glucose-6-phosphate
  4. Two NADH molecules Correct answer.

Explanation

Glycolysis consumes two ATP and produces four ATP, two NADH, and two pyruvate molecules per glucose, giving a net gain of two ATP. The NADH carries electrons to the mitochondria for use in oxidative phosphorylation.

Question 10Exercise Sciences (scientific foundations)

Which enzyme catalyzes the rate-limiting step of the Krebs cycle?

  1. Hexokinase
  2. Creatine kinase
  3. Phosphofructokinase (PFK)
  4. Isocitrate dehydrogenase Correct answer.

Explanation

Isocitrate dehydrogenase catalyzes the rate-limiting step of the Krebs cycle and is regulated by the energy charge of the cell, being inhibited by ATP and NADH and activated by ADP. This control helps match oxidative flux to cellular energy demand.

Question 11Exercise Sciences (scientific foundations)

According to the sliding filament theory, which region of the sarcomere shortens during a concentric contraction?

  1. The actin filaments themselves
  2. The A band only
  3. The myosin filaments
  4. The H zone and the I band Correct answer.

Explanation

During a concentric contraction, actin filaments are pulled toward the center of the sarcomere, narrowing the H zone and shortening the I band. The thick filaments do not change length, so the A band remains constant.

Question 12Exercise Sciences (scientific foundations)

Which proprioceptor detects the magnitude and rate of change in muscle length?

  1. Golgi tendon organ
  2. Muscle spindle Correct answer.
  3. Ruffini ending
  4. Pacinian corpuscle

Explanation

Muscle spindles lie parallel to the extrafusal fibers and signal both the amount and the speed of stretch, producing the stretch reflex. Their sensitivity is adjusted by gamma motor neuron activity during movement.

Question 13Exercise Sciences (scientific foundations)

Which equation states that oxygen consumption equals cardiac output multiplied by the arterial-venous oxygen difference?

  1. The Henderson-Hasselbalch equation
  2. The Bohr equation
  3. The Fick equation Correct answer.
  4. The Frank-Starling equation

Explanation

The Fick equation expresses oxygen uptake as the product of cardiac output and the arterial-venous oxygen difference, so an increase in either factor raises whole-body oxygen consumption. It is commonly used to explain how central and peripheral adaptations both raise VO2max.

Question 14Exercise Sciences (scientific foundations)

Active tension produced by a muscle is greatest at which length?

  1. When shortened to 70% of resting length
  2. When stretched to 130% of resting length
  3. Force is independent of muscle length
  4. At resting length Correct answer.

Explanation

At resting length, thick and thin filament overlap is near optimal, allowing the greatest number of cross-bridges to form and therefore the greatest active tension. Stretching reduces overlap, and shortening causes filament interference and reduced overlap.

Question 15Exercise Sciences (scientific foundations)

Which hormonal change occurs during prolonged moderate-intensity aerobic exercise?

  1. A decrease in plasma cortisol
  2. An increase in plasma insulin
  3. A decrease in plasma glucagon
  4. A decrease in plasma insulin Correct answer.

Explanation

Plasma insulin falls during prolonged aerobic exercise while glucagon, cortisol, growth hormone, and catecholamines rise. This shift favors mobilization of glucose and free fatty acids to fuel working muscle.

Question 16Exercise Sciences (scientific foundations)

Which of the following is a typical chronic adaptation to aerobic endurance training?

  1. Increased resting heart rate
  2. Higher stroke volume at submaximal workloads Correct answer.
  3. Increased mitochondrial volume
  4. Decreased capillary density in trained muscle

Explanation

Endurance training increases plasma volume, left ventricular cavity size, and myocardial contractility, all of which raise stroke volume so that a given submaximal cardiac output is achieved at a lower heart rate. Capillary density and mitochondrial volume also increase with training.

Question 17Exercise Sciences (scientific foundations)

The lactate threshold is best defined as the exercise intensity at which which of the following occurs?

  1. Muscle glycogen becomes fully depleted
  2. Maximal oxygen uptake is achieved
  3. Ventilation begins to decrease
  4. Lactate accumulates above resting levels Correct answer.

Explanation

The lactate threshold is the intensity at which blood lactate begins to rise systematically above resting concentrations, reflecting lactate appearance exceeding clearance. It is used to anchor training intensities and to predict endurance performance.

Question 18Exercise Sciences (scientific foundations)

Which muscle is a primary hip extensor?

  1. Rectus femoris
  2. Gluteus maximus Correct answer.
  3. Iliopsoas
  4. Sartorius

Explanation

The gluteus maximus is the largest and strongest hip extensor and is heavily active during rising from a squat or accelerating up a hill. The hamstrings also contribute to hip extension.

Question 19Exercise Sciences (scientific foundations)

The stretch-shortening cycle enhances force production primarily through which mechanism?

  1. Greater overlap of actin and myosin filaments
  2. Storage and recoil of elastic energy Correct answer.
  3. Slower cross-bridge cycling
  4. Increased intramuscular temperature

Explanation

A rapid eccentric phase stores elastic energy in tendons and the series elastic component and stimulates the stretch reflex, so the subsequent concentric phase produces more force and power. This underlies the improved performance seen in movements such as a countermovement jump.

Question 20Exercise Sciences (scientific foundations)

The synthesis of glucose from non-carbohydrate precursors such as amino acids and glycerol is called which of the following?

  1. Gluconeogenesis Correct answer.
  2. Glycolysis
  3. Lipolysis
  4. Glycogenolysis

Explanation

Gluconeogenesis is the formation of new glucose from non-carbohydrate precursors such as amino acids, glycerol, and lactate, occurring mainly in the liver and to a lesser extent in the kidney. It helps maintain blood glucose during prolonged exercise and fasting.

Question 21Exercise Sciences (scientific foundations)

According to the Henneman size principle, motor units are recruited in which order as force requirements increase?

  1. From largest to smallest
  2. In a random order
  3. All at once, regardless of force
  4. From smallest to largest Correct answer.

Explanation

The size principle holds that motor units are activated in order of increasing size, so small, low-threshold units dominated by Type I fibers are recruited first and larger, higher-threshold units are added as force demand rises. This orderly recruitment allows smooth gradation of force.

Question 22Exercise Sciences (scientific foundations)

During intense exercise, increased PCO2, hydrogen ion concentration, and temperature cause which change in the oxyhemoglobin dissociation curve?

  1. No shift, because only 2,3-BPG alters the curve
  2. A leftward shift, increasing hemoglobin's affinity for oxygen
  3. A rightward shift, decreasing hemoglobin's affinity for oxygen Correct answer.
  4. A rightward shift, increasing hemoglobin's affinity for oxygen

Explanation

Elevated carbon dioxide, hydrogen ions, and temperature shift the oxyhemoglobin dissociation curve to the right, a phenomenon known as the Bohr effect. A rightward shift lowers hemoglobin's affinity for oxygen, so more oxygen is unloaded where metabolism is highest.

Question 23Exercise Sciences (scientific foundations)

According to the force-velocity relationship for concentric actions, what happens to force as shortening velocity increases?

  1. Force increases
  2. Force decreases Correct answer.
  3. Force remains constant
  4. Force rises and then plateaus

Explanation

For concentric actions, force and shortening velocity are inversely related: as velocity increases, fewer cross-bridges remain attached at any moment, so the force the muscle can produce declines. Force is greatest during isometric and eccentric actions, where shortening velocity is zero or negative.

Question 24Exercise Sciences (scientific foundations)

In the cross-bridge cycle, ATP binding to the myosin head is required for which step?

  1. Calcium binding to troponin
  2. Formation of the actin-myosin bond
  3. Detachment of myosin from actin Correct answer.
  4. Exposure of actin binding sites

Explanation

After the power stroke, ATP binds to the myosin head and is hydrolyzed, which detaches myosin from actin and re-cocks the head for the next cycle. Without ATP, cross-bridges remain attached, which is the basis of rigor.

Question 25Exercise Sciences (scientific foundations)

Which neural adaptation most contributes to strength gains during the first few weeks of a resistance training program?

  1. Increased capillary density
  2. Enhanced motor unit recruitment Correct answer.
  3. Muscle fiber hypertrophy
  4. Increased mitochondrial enzyme activity

Explanation

Early strength gains exceed what muscle growth alone would predict and are attributed largely to neural factors, including greater motor unit recruitment, higher firing rates, and improved intermuscular coordination. Measurable hypertrophy generally requires several weeks of training.

Question 26Exercise Sciences (scientific foundations)

Which energy system is the primary source of ATP during a maximal-effort sprint lasting about 6 seconds?

  1. Anaerobic glycolysis
  2. Fat oxidation
  3. Aerobic metabolism
  4. Phosphagen system Correct answer.

Explanation

The phosphagen system uses stored creatine phosphate to rapidly regenerate ATP for very brief, maximal efforts. Its capacity is small, so it predominates only during the first several seconds of intense activity.

Question 27Exercise Sciences (scientific foundations)

Which organelle releases calcium ions to initiate skeletal muscle contraction?

  1. Mitochondrion
  2. Golgi apparatus
  3. Sarcoplasmic reticulum Correct answer.
  4. Nucleus

Explanation

The sarcoplasmic reticulum stores calcium and releases it when an action potential travels along the muscle fiber. The released calcium binds troponin and allows cross-bridge cycling to begin.

Question 28Exercise Sciences (scientific foundations)

The functional contractile unit of a skeletal muscle fiber is the

  1. Sarcomere Correct answer.
  2. Myofilament
  3. Myofibril
  4. Fascicle

Explanation

A sarcomere is the segment between two Z lines and contains the actin and myosin filaments that generate tension. It is repeated along the length of each myofibril.

Question 29Exercise Sciences (scientific foundations)

Which vessel carries deoxygenated blood from the right ventricle to the lungs?

  1. Coronary artery
  2. Aorta
  3. Pulmonary vein
  4. Pulmonary artery Correct answer.

Explanation

The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs for gas exchange. This is an exception to the usual rule that arteries carry oxygenated blood.

Question 30Exercise Sciences (scientific foundations)

Which hormone promotes glycogen breakdown in the liver and raises blood glucose?

  1. Aldosterone
  2. Glucagon Correct answer.
  3. Calcitonin
  4. Insulin

Explanation

Glucagon is released from pancreatic alpha cells and stimulates hepatic glycogenolysis and gluconeogenesis, increasing blood glucose. It acts largely opposite to insulin.

Question 31Exercise Sciences (scientific foundations)

Which vitamin is required for intestinal calcium absorption?

  1. Vitamin D Correct answer.
  2. Vitamin A
  3. Vitamin C
  4. Vitamin K

Explanation

Vitamin D supports calcium absorption by increasing calcium transport proteins in the intestine. Adequate vitamin D is therefore important for bone health and normal calcium regulation.

Question 32Exercise Sciences (scientific foundations)

Resting skeletal muscle uses which fuel as its primary energy source?

  1. Blood glucose
  2. Muscle glycogen
  3. Ketone bodies
  4. Fatty acids Correct answer.

Explanation

At rest, skeletal muscle relies mainly on fatty acid oxidation because oxygen is plentiful and energy demand is low. Carbohydrate use increases as exercise intensity rises.

Question 33Exercise Sciences (scientific foundations)

Which structure initiates the electrical impulse for the heart?

  1. Purkinje fibers
  2. Sinoatrial node Correct answer.
  3. Atrioventricular node
  4. Bundle of His

Explanation

The sinoatrial node has the highest rate of spontaneous depolarization and normally sets the heart's rhythm. Its impulse spreads through the atria and then to the atrioventricular node.

Question 34Exercise Sciences (scientific foundations)

During a 400-meter sprint, which energy system supplies the greatest proportion of ATP?

  1. Anaerobic glycolysis Correct answer.
  2. Phosphagen system
  3. Fat oxidation
  4. Aerobic oxidation

Explanation

A 400-meter sprint typically lasts long enough that anaerobic glycolysis becomes the dominant ATP source. The phosphagen system contributes early, but its stored creatine phosphate is depleted quickly.

Question 35Exercise Sciences (scientific foundations)

A swimmer hyperventilates before a race, reducing arterial PCO2. This change produces which condition?

  1. Respiratory alkalosis Correct answer.
  2. Metabolic acidosis
  3. Metabolic alkalosis
  4. Respiratory acidosis

Explanation

Hyperventilation lowers arterial carbon dioxide, which reduces hydrogen ion concentration and raises blood pH. This primary respiratory change is therefore respiratory alkalosis.

Question 36Exercise Sciences (scientific foundations)

During exercise in a hot environment, which combination of responses increases heat loss?

  1. Cutaneous vasodilation and shivering
  2. Cutaneous vasoconstriction and sweating
  3. Cutaneous vasoconstriction and shivering
  4. Cutaneous vasodilation and sweating Correct answer.

Explanation

Cutaneous vasodilation increases skin blood flow to deliver heat to the surface, and sweating adds evaporative cooling. Together these responses promote heat dissipation during exercise in the heat.

Question 37Exercise Sciences (scientific foundations)

For the same muscle, which action can produce the greatest force?

  1. Concentric at fast velocity
  2. Isometric at short length
  3. Concentric at slow velocity
  4. Eccentric Correct answer.

Explanation

Eccentric actions can generate greater force than concentric or isometric actions because cross-bridges are forcibly detached while resisting lengthening. The series elastic component also contributes to eccentric force production.

Question 38Exercise Sciences (scientific foundations)

Which cardiovascular adaptation most increases VO2max after several months of aerobic endurance training?

  1. Decreased plasma volume
  2. Increased stroke volume Correct answer.
  3. Lowered maximal cardiac output
  4. Reduced capillary density

Explanation

Aerobic training enlarges plasma volume and ventricular filling, increasing stroke volume and maximal cardiac output. This is a major reason VO2max rises with endurance training.

Question 39Exercise Sciences (scientific foundations)

Performing the Valsalva maneuver during a heavy squat primarily causes which acute response?

  1. Decreased blood pressure
  2. Increased intrathoracic pressure Correct answer.
  3. Decreased intrathoracic pressure
  4. Increased venous return to the heart

Explanation

The Valsalva maneuver involves forceful exhalation against a closed glottis, which raises intrathoracic pressure. This can stabilize the trunk but also impedes venous return and acutely alters blood pressure.

Question 40Exercise Sciences (scientific foundations)

Which muscle action occurs when a muscle lengthens while producing force?

  1. Concentric
  2. Eccentric Correct answer.
  3. Isokinetic
  4. Isometric

Explanation

An eccentric action occurs when external resistance exceeds the force produced by the muscle, so the muscle lengthens while active. This action is common when lowering a load under control.

Question 41Exercise Sciences (scientific foundations)

Which characteristic most distinguishes Type I from Type II muscle fibers?

  1. Greater peak force production
  2. Larger cross-sectional area
  3. Greater resistance to fatigue Correct answer.
  4. Higher myosin ATPase activity

Explanation

Type I fibers have high oxidative capacity, dense capillary supply, and many mitochondria, making them highly fatigue resistant. Type II fibers generally produce force more quickly but fatigue sooner.

Question 42Exercise Sciences (scientific foundations)

Which factor shifts the oxyhemoglobin dissociation curve to the right?

  1. Increased hemoglobin affinity
  2. Decreased hydrogen ion concentration
  3. Increased 2,3-diphosphoglycerate Correct answer.
  4. Decreased temperature

Explanation

Increased 2,3-diphosphoglycerate reduces hemoglobin's affinity for oxygen and shifts the curve right. A rightward shift enhances oxygen unloading to active tissues.

Question 43Exercise Sciences (scientific foundations)

During prolonged submaximal exercise, fatigue is most closely associated with depletion of which fuel?

  1. Muscle glycogen Correct answer.
  2. Blood fatty acids
  3. Intramuscular triglycerides
  4. Liver glycogen

Explanation

Muscle glycogen becomes progressively depleted during prolonged submaximal exercise, and low glycogen is strongly linked to fatigue. Carbohydrate ingestion can help delay this decline.

Question 44Exercise Sciences (scientific foundations)

Which movement occurs primarily in the sagittal plane?

  1. Shoulder abduction
  2. Elbow flexion Correct answer.
  3. Wrist radial deviation
  4. Hip circumduction

Explanation

Elbow flexion occurs in the sagittal plane, which divides the body into left and right portions. Sagittal-plane movements include flexion and extension.

Question 45Exercise Sciences (scientific foundations)

After aerobic training, which change at a given submaximal intensity is typical?

  1. Lower heart rate Correct answer.
  2. Higher heart rate
  3. Higher blood lactate
  4. Lower stroke volume

Explanation

Aerobic training increases stroke volume and oxidative capacity, so a given submaximal workload requires a lower heart rate. Blood lactate at that workload also typically falls.

Question 46Exercise Sciences (scientific foundations)

Aerobic training lowers blood lactate concentration at a fixed submaximal workload primarily because of which adaptation?

  1. Lowered oxidative enzyme activity
  2. Increased mitochondrial density and lactate oxidation Correct answer.
  3. Decreased capillary density
  4. Reduced muscle blood flow

Explanation

Endurance training increases mitochondrial density and oxidative enzyme activity, improving lactate clearance and oxidation. This allows a given submaximal workload to be performed with less lactate accumulation.

Question 47Exercise Sciences (scientific foundations)

Which factor best explains the greater force produced during an eccentric action compared with a concentric action?

  1. Less tension is stored in the series elastic component
  2. Muscle spindles are inhibited
  3. More motor units are always recruited
  4. Cross-bridges are forcibly detached while resisting lengthening Correct answer.

Explanation

During eccentric actions, activated cross-bridges resist lengthening and are forcibly detached, allowing high tension per cross-bridge. Elastic energy storage and use also contribute to the greater force output.

Question 48Exercise Sciences (scientific foundations)

Which condition increases the affinity of hemoglobin for oxygen?

  1. Decreased hydrogen ion concentration Correct answer.
  2. Increased temperature
  3. Increased 2,3-diphosphoglycerate
  4. Increased PCO2

Explanation

A decrease in hydrogen ion concentration raises pH and shifts the oxyhemoglobin dissociation curve left. A leftward shift means hemoglobin binds oxygen more tightly and unloads less oxygen to tissues.

Question 49Exercise Sciences (scientific foundations)

During steady-state exercise, which change in substrate utilization occurs as exercise duration increases from 30 to 120 minutes at the same intensity?

  1. Decreased reliance on fat oxidation
  2. No change in substrate use
  3. Increased reliance on fat oxidation Correct answer.
  4. Increased reliance on muscle glycogen

Explanation

As exercise duration increases, muscle glycogen declines and fat oxidation contributes a progressively larger share of ATP production. Hormonal changes such as rising catecholamines and falling insulin support lipolysis and fat use.

Question 50Exercise Sciences (scientific foundations)

Which factor most directly determines the rate of oxygen diffusion from alveolar air into pulmonary capillary blood?

  1. Hemoglobin concentration in blood
  2. Cardiac output
  3. Ventilation rate
  4. Partial pressure gradient for oxygen Correct answer.

Explanation

Diffusion follows Fick's law, so the partial pressure gradient between alveolar air and capillary blood is the direct driving force for oxygen movement. Other factors such as surface area and membrane thickness also affect diffusion.