2024 IB DP Sports, Exercise and Health Science 模擬試題連答案詳解

During sub-maximal aerobic exercise, stroke volume increases rapidly during the initial stages of exercise and plateaus at approximately 40–60% of \(VO_2\) max in untrained individuals. Heart rate, however, increases linearly with exercise intensity and workload until maximal levels are approached.

Award [1] for the correct option (b). No partial marks are awarded for multiple-choice questions.

An isometric contraction occurs when the muscle develops tension but does not change length, and the joint angle remains constant. Holding a static handstand involves isometric contraction of the triceps brachii to keep the elbows locked in extension against gravity.

Award [1] for the correct option (c).

High glycaemic index (GI) foods cause a rapid rise in blood glucose levels. Consuming high-GI foods immediately post-exercise is highly effective because it rapidly stimulates insulin secretion, enhancing the rate of glycogen resynthesis in depleted muscle tissues.

Award [1] for the correct option (b).

Bandwidth feedback is a technique where feedback is only provided when the performer's error falls outside a pre-defined range or 'bandwidth' of acceptable performance. If the performance is within this range, no feedback is given.

Award [1] for the correct option (a).

Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. The action force exerted by the runner against the starting blocks results in an equal and opposite reaction force from the blocks acting on the runner, propelling them forward.

Award [1] for the correct option (c).

The reciprocal style of teaching involves students working in pairs where one is the 'doer' and the other is the 'observer' who provides immediate, structured feedback based on criteria provided by the teacher.

Award [1] for the correct option (b).

Catastrophe theory predicts that high levels of cognitive anxiety, combined with elevated physiological arousal, will lead to a sudden and large decline in performance (a 'catastrophe') rather than a gradual, symmetrical decline as predicted by the Inverted-U hypothesis.

Award [1] for the correct option (c).

Self-Determination Theory argues that there are three innate and universal psychological needs: autonomy (the need to feel in control of one's own behaviors), competence (the need to feel effective in interacting with the environment), and relatedness (the need to feel a sense of belonging and connection with others).

Award [1] for the correct option (a).

During graded exercise, the active skeletal muscles extract significantly more oxygen from the blood to support aerobic energy systems. This causes the oxygen concentration in mixed venous blood to decrease. Since arterial oxygen concentration remains relatively constant due to effective respiration and pulmonary diffusion, the difference between arterial and venous oxygen content (a-vO\(_2\) difference) increases as exercise intensity rises.

[1] Award 1 mark for selecting the correct option (d). Other options are incorrect because the difference increases (not decreases or remains constant) due to a reduction in venous oxygen concentration from high muscle extraction.

According to the sliding filament theory, when an action potential depolarizes the muscle fiber, calcium ions are released from the sarcoplasmic reticulum. These ions bind to troponin, which changes shape and shifts tropomyosin away from the active binding sites on the actin filament. This exposes the sites, allowing myosin heads to bind and form cross-bridges.

[1] Award 1 mark for the correct option (a). All other options represent incorrect physiological steps in the excitation-contraction coupling process.

Immediately post-exercise, muscle insulin sensitivity and glucose transporter (GLUT-4) activity are at their peak. Consuming high-glycemic index (high-GI) carbohydrates rapidly raises blood glucose and insulin levels, maximizing the rate of glycogen resynthesis during this critical recovery window.

[1] Award 1 mark for identifying high-GI foods consumed immediately post-exercise as the optimal combination. Other options delay or slow down the replenishment of glycogen stores.

The feedback is delivered after the movement is completed (terminal). It describes the kinematic characteristic of the movement itself ('racket face was slightly open'), which refers to the quality and execution of the movement, making it Knowledge of Performance (KP). Knowledge of Results (KR) would focus strictly on the outcome (e.g., 'the ball went long').

[1] Award 1 mark for the correct option (b). The other options are incorrect because the feedback is delivered after the action (terminal) and describes the movement mechanics rather than just the outcome.

A standing calf raise acts as a second-class lever. The fulcrum (pivot point) is at the ball of the foot (metatarsal-phalangeal joints), the load (body weight) acts downwards through the middle of the foot, and the effort (muscle force) is applied upwards by the gastrocnemius/soleus via the Achilles tendon at the heel. Therefore, the load lies between the fulcrum and the effort.

[1] Award 1 mark for identifying both the correct lever class (second class) and the correct sequence of components (load between fulcrum and effort).

Self-Determination Theory (SDT) posits that three innate psychological needs—autonomy (feeling in control of one's actions), competence (feeling effective in performing tasks), and relatedness (feeling connected to others)—are essential for psychological growth and intrinsic motivation.

[1] Award 1 mark for option (a). Options (b), (c), and (d) include incorrect needs or concepts from different motivational frameworks.

The immediate, rapid increase in ventilation at the onset of exercise is driven by neural (neurogenic) mechanisms, including central command (anticipatory) and feedback from joint and muscle proprioceptors. The subsequent, slower increase to steady-state is regulated by humoral (chemical) factors, such as changes in arterial partial pressure of carbon dioxide (PCO\(_2\)), PO\(_2\), and pH, which are sensed by central and peripheral chemoreceptors.

[1] Award 1 mark for option (b). Option (a) and (c) reverse the roles of neural and humoral control. Option (d) incorrectly identifies temperature and lactic acid as the primary drivers of these two distinct phases.

Hardy's Catastrophe Theory suggests that when cognitive anxiety is high, increases in physiological arousal up to a certain point can be beneficial to performance. However, if physiological arousal exceeds the optimal threshold, a catastrophic (sudden and severe) decline in performance occurs. To recover, the athlete must significantly lower their physiological arousal below the initial threshold.

[1] Award 1 mark for the correct option (c). Option (a) describes the traditional inverted-U hypothesis under low cognitive anxiety, while options (b) and (d) are incorrect interpretations of catastrophe theory.

In untrained individuals, stroke volume increases during progressive exercise but plateaus at approximately 40% to 60% of \(VO_2\) max. Any further increase in cardiac output beyond this intensity is achieved solely through an increase in heart rate. Therefore, cardiac output continues to rise while stroke volume remains stable.

Award 1 mark for identifying that stroke volume plateaus while cardiac output continues to rise.

During the preparation phase of a kick, the knee is flexed. The biceps femoris (hamstring muscle) acts as the agonist and contracts concentrically to cause knee flexion. The rectus femoris (quadriceps muscle) acts as the antagonist and must relax and lengthen to allow the movement.

Award 1 mark for the correct combination of roles (agonist/antagonist) and contraction type (concentric/relaxing).

To maximize muscle glycogen stores (carbohydrate loading), athletes should consume a high-carbohydrate diet (approx. 7-10g/kg of body weight) while simultaneously tapering (reducing) their training volume. This ensures that the consumed carbohydrates are stored as glycogen rather than depleted through intense training.

Award 1 mark for selecting high-carbohydrate diet combined with training tapering.

The feedback is extrinsic (augmented) because it comes from an external source (the video replay) rather than the gymnast's internal sensory systems. It is Knowledge of Performance (KP) because it provides information about the quality or pattern of the movement (hip and shoulder alignment) rather than the outcome (such as the score).

Award 1 mark for identifying extrinsic and Knowledge of Performance (KP).

A calf raise represents a second-class lever. The fulcrum is at the metatarsophalangeal joints (balls of the feet), the load (body weight) acts downwards through the middle of the foot, and the effort is applied upwards by the gastrocnemius muscle via the Achilles tendon at the heel. Therefore, the load is in the middle.

Award 1 mark for identifying it as a second-class lever with the load in the middle.

Intrinsic motivation refers to doing an activity for its inherent satisfaction and enjoyment rather than for some separable consequence. A runner who trail runs simply for the joy of movement and being in nature is driven by intrinsic factors. All other options describe extrinsic motivators (trophies, avoiding disappointment, social status).

Award 1 mark for selecting the scenario driven by enjoyment and inherent satisfaction.

At the very start of exercise, ventilation increases abruptly before any chemical changes (like arterial \(CO_2\) or pH) have occurred in the blood. This rapid phase is driven by neural mechanisms: central command from the motor cortex and sensory feedback (proprioceptors) from the moving joints and muscles.

Award 1 mark for identifying neural/proprioceptive mechanisms as the primary cause of the immediate ventilatory rise.

When an action potential reaches the presynaptic terminal, it depolarizes the membrane, opening voltage-gated calcium channels. The influx of calcium ions (\(Ca^{2+}\)) into the presynaptic terminal triggers synaptic vesicles containing acetylcholine to fuse with the presynaptic membrane and release their neurotransmitters into the synaptic cleft via exocytosis.

Award 1 mark for identifying that calcium ions trigger the fusion of vesicles to release neurotransmitters.

During prolonged submaximal exercise, especially in hot conditions, sweat rate is high, leading to a decrease in blood plasma volume. This reduces venous return and stroke volume. To maintain cardiac output, the heart rate must progressively increase. This progressive increase in heart rate alongside a decrease in stroke volume is termed cardiovascular drift.

Award 1 mark for identifying option B as the correct answer.

During the descending (downward) phase of a squat, the knee joint flexes while the quadriceps muscles actively lengthen to control the rate of descent against gravity. This lengthening of a muscle under tension is classified as an eccentric contraction.

Award 1 mark for identifying option C as the correct answer.

Glycogen is a complex polysaccharide made of glucose units. It is the primary storage form of carbohydrates in animals and is stored mainly in the liver and skeletal muscles to be mobilized during metabolic demand.

Award 1 mark for identifying option A as the correct answer.

The cognitive stage is the initial phase of learning where the athlete tries to understand the requirements of the task. Performance is characterized by high variability, a large number of errors, and a strong reliance on external feedback and cognitive processing.

Award 1 mark for identifying option C as the correct answer.

Newton's third law of motion states that for every action force, there is an equal and opposite reaction force. Therefore, when the sprinter exerts a force backward and downward, the starting blocks exert an equal force of 800 N forward and upward against the sprinter's feet.

Award 1 mark for identifying option C as the correct answer.

The fast component of EPOC occurs immediately after exercise. Its primary functions are to resynthesize phosphocreatine (PCr) in the muscles and to replenish oxygen stores in myoglobin and hemoglobin.

Award 1 mark for identifying option A as the correct answer.

(a) There is a direct positive linear relationship; as workload increases, heart rate increases for both groups. (b) Cardiac output \(Q = \text{HR} \times \text{SV}\). At 200 W: Trained \(Q = 138 \times 135\text{ mL} = 18.63\text{ L/min}\). Untrained \(Q = 165 \times 95\text{ mL} = 15.675\text{ L/min}\). Difference = \(18.63 - 15.675 = 2.955\text{ L/min}\) (accept 2.95 to 2.96 L/min). (c) Trained rowers have overall higher stroke volume at all workloads. In untrained rowers, SV plateaus at 200 W (95 mL) and does not increase at 300 W. In trained rowers, SV continues to rise from 100 W to 300 W (120 to 140 mL) due to structural adaptations like increased left ventricular volume. (d) Cardiovascular drift is the gradual increase in heart rate and simultaneous decrease in stroke volume during prolonged steady-state exercise, caused by a decrease in blood plasma volume due to sweating.

(a) Award 1 mark for stating the positive linear relationship. (b) Award 1 mark for calculating both individual cardiac outputs correctly (Trained = 18.63 L/min, Untrained = 15.675 L/min or 15.68 L/min) and 1 mark for the correct final difference of 2.955 L/min (accept 2.95 to 2.96 L/min). (c) Award 1 mark for stating trained rowers have overall higher SV, 1 mark for noting the plateau in untrained rowers at 200 W, and 1 mark for noting the continuous increase in trained rowers up to 300 W. (d) Award 1 mark for defining cardiovascular drift (increasing HR, decreasing SV, constant Q) and 1 mark for attributing it to fluid loss/sweating/reduced plasma volume.

(a) At 6 hours, the difference is \(210 - 140 = 70\text{ mmol/kg}\) dry weight. (b) Both groups show an upward trend in glycogen replenishment over 24 hours. The High-GI group replenishes glycogen at a faster rate initially and maintains higher concentrations throughout the entire 24-hour period compared to the Low-GI group. (c) High-GI foods are digested rapidly, causing a sharp rise in blood glucose. This triggers a large secretion of insulin, which stimulates the translocation of GLUT-4 transporters to the cell membrane, accelerating glucose uptake and activating the enzyme glycogen synthase. (d) Carbohydrate loading maximizes muscle and liver glycogen stores (glycogen supercompensation) before a race, which delays depletion of glycogen stores, postponing fatigue and maintaining high-intensity performance for longer.

(a) Award 1 mark for the correct calculation: 70 mmol/kg (must include unit). (b) Award 1 mark for stating that both increase over time, and 1 mark for stating that the High-GI diet achieves higher levels/rates of replenishment at all stages. (c) Award 1 mark for mentioning the rapid increase in blood glucose and subsequent insulin spike. Award 1 mark for explaining that insulin promotes glucose uptake into muscles (via GLUT-4) and activates glycogen synthesis. (d) Award 1 mark for mentioning glycogen supercompensation or maximization of stores. Award 1 mark for explaining how this delays fatigue / sustains aerobic energy production.

(a) A sarcomere is the basic functional unit of a myofibril, bounded at both ends by Z-lines (or Z-discs). It contains thin actin filaments anchored to the Z-lines and thick myosin filaments located centrally within the A-band, overlapping with the actin filaments. (b) Released calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the active binding sites on the actin filament. Myosin heads (energized by ATP hydrolysis) bind to these exposed active sites on actin to form cross-bridges. The release of ADP and inorganic phosphate triggers the power stroke, where the myosin head pivots, pulling the actin filament toward the M-line. (c) Concentric contraction: muscle shortens while generating tension (e.g., the quadriceps shortening during the upward phase of a vertical jump). Eccentric contraction: muscle lengthens under tension (e.g., the quadriceps lengthening while landing from a jump).

(a) Award 1 mark for identifying Z-lines as the boundaries of a sarcomere. Award 1 mark for identifying actin as thin filaments (attached to Z-lines). Award 1 mark for identifying myosin as thick filaments (situated in the center/A-band). (b) Award 1 mark for stating calcium binds to troponin and shifts tropomyosin. Award 1 mark for cross-bridge formation between myosin head and actin binding site. Award 1 mark for explaining the power stroke (myosin head pivoting and pulling actin). (c) Award 1 mark for distinguishing concentric (shortening under tension) with a valid example. Award 1 mark for distinguishing eccentric (lengthening under tension) with a valid example.

(a) Newton's First Law (Inertia): The sprinter remains stationary in the blocks until the force generated by muscular contraction exceeds their inertia. Newton's Second Law (Acceleration): The sprinter's acceleration is proportional to the net force applied to the blocks and inversely proportional to their body mass (\(F = ma\)). Newton's Third Law (Action/Reaction): The sprinter exerts a backward force on the blocks (action), and the blocks exert an equal and opposite forward force on the sprinter (reaction), propelling them forward. (b) Center of mass is the point around which the body's mass is equally distributed in all directions. During the Fosbury Flop, the athlete arches their back over the bar. Because their head and legs hang lower than their elevated midsection, the calculated average position of mass (center of mass) is projected outside and below the physical body (underneath the bar). (c) The elbow joint during a bicep curl acts as a third-class lever. The effort (force exerted by the biceps muscle insertion on the radius) is located between the fulcrum (the elbow joint) and the load (the dumbbell held in the hand).

(a) Award 1 mark for Newton's 1st law application (overcoming inertia to move). Award 1 mark for Newton's 2nd law application (force determines acceleration, \(F=ma\)). Award 1 mark for Newton's 3rd law application (pushing blocks results in forward propulsion). (b) Award 1 mark for defining center of mass. Award 1 mark for explaining that arching the body (Fosbury Flop) distributes mass such that the center of mass falls below/outside the curved torso. (c) Award 1 mark for identifying it as a third-class lever. Award 1 mark for correctly stating the positions: effort is in the middle, between the fulcrum and the load.

(a) At low-intensity exercise (approx. <50% of \(VO_2\) max), fats are the primary substrate for energy production due to abundant availability and high ATP yield per molecule of oxygen. As intensity increases to moderate levels, the contribution of carbohydrate oxidation rises. At high-intensity exercise (>75% \(VO_2\) max), carbohydrates (muscle glycogen and blood glucose) become the dominant energy source because carbohydrate metabolism is faster and more oxygen-efficient than fat metabolism. (b) Dehydration reduces plasma volume, leading to decreased venous return and stroke volume. To maintain cardiac output, heart rate increases, a phenomenon known as cardiovascular drift. If dehydration is severe, cardiac output decreases, impairing oxygen delivery to working muscles. For thermoregulation, reduced blood volume causes vasoconstriction in the skin, decreasing skin blood flow and convective heat loss. Sweat rate is also reduced, severely limiting evaporative cooling, which leads to a rapid rise in core body temperature and increases the risk of heat illness. (c) Before the marathon, the runner should carbohydrate load (8-12 g/kg/day) 2-3 days prior to maximize glycogen stores, consume a high-carbohydrate, low-fiber meal 3-4 hours before, and pre-hydrate (5-7 mL/kg). During the race, they should consume 30-90g of carbohydrates per hour and drink fluids with electrolytes (primarily sodium) every 15-20 minutes to prevent >2% body mass loss. After the race, the runner must rehydrate with 1.25 to 1.5 L of fluid per kg of body mass lost, consume high-glycemic carbohydrates immediately to restore glycogen, and consume 20-25g of high-quality protein to support muscle protein synthesis.

(a) Award up to [4] marks total: Award [1] for noting that fats are the primary fuel at low intensities. Award [1] for noting that carbohydrates become the dominant fuel at high intensities. Award [1] for explaining that carbohydrates are more oxygen-efficient / yield ATP more quickly than fats. Award [1] for mentioning the 'crossover concept' or shift in muscle fiber recruitment (fast-twitch fibers rely more on carbs). (b) Award up to [7] marks total: Award [1] for stating dehydration reduces plasma/blood volume. Award [1] for stating reduced blood volume decreases stroke volume and venous return. Award [1] for explaining the compensatory increase in heart rate (cardiovascular drift). Award [1] for noting the potential decrease in cardiac output and oxygen transport. Award [1] for stating that skin blood flow / peripheral vasodilation is reduced. Award [1] for stating that sweat rate decreases. Award [1] for explaining that reduced skin blood flow and sweat rate impair evaporative/convective cooling, leading to elevated core body temperature. (c) Award up to [9] marks total: Award up to [3] marks for 'Before' strategies (e.g., carbohydrate loading to maximize glycogen [1], pre-event meal characteristics [1], pre-hydration guidelines [1]). Award up to [3] marks for 'During' strategies (e.g., carbohydrate intake rates of 30-90g/hr [1], regular fluid consumption to avoid >2% mass loss [1], inclusion of sodium/electrolytes to maintain osmotic drive and prevent hyponatremia/cramping [1]). Award up to [3] marks for 'After' strategies (e.g., rehydration volume of 1.25-1.5 L per kg of weight lost [1], high-glycemic carbohydrates immediately for rapid glycogen resynthesis [1], protein intake of 20-25g for muscle repair [1]).

(a) At low-intensity exercise (approx. <50% of \(VO_2\) max), fats are the primary substrate for energy production due to abundant availability and high ATP yield per molecule of oxygen. As intensity increases to moderate levels, the contribution of carbohydrate oxidation rises. At high-intensity exercise (>75% \(VO_2\) max), carbohydrates (muscle glycogen and blood glucose) become the dominant energy source because carbohydrate metabolism is faster and more oxygen-efficient than fat metabolism. (b) Dehydration reduces plasma volume, leading to decreased venous return and stroke volume. To maintain cardiac output, heart rate increases, a phenomenon known as cardiovascular drift. If dehydration is severe, cardiac output decreases, impairing oxygen delivery to working muscles. For thermoregulation, reduced blood volume causes vasoconstriction in the skin, decreasing skin blood flow and convective heat loss. Sweat rate is also reduced, severely limiting evaporative cooling, which leads to a rapid rise in core body temperature and increases the risk of heat illness. (c) Before the marathon, the runner should carbohydrate load (8-12 g/kg/day) 2-3 days prior to maximize glycogen stores, consume a high-carbohydrate, low-fiber meal 3-4 hours before, and pre-hydrate (5-7 mL/kg). During the race, they should consume 30-90g of carbohydrates per hour and drink fluids with electrolytes (primarily sodium) every 15-20 minutes to prevent >2% body mass loss. After the race, the runner must rehydrate with 1.25 to 1.5 L of fluid per kg of body mass lost, consume high-glycemic carbohydrates immediately to restore glycogen, and consume 20-25g of high-quality protein to support muscle protein synthesis.

(a) Award up to [4] marks total: Award [1] for noting that fats are the primary fuel at low intensities. Award [1] for noting that carbohydrates become the dominant fuel at high intensities. Award [1] for explaining that carbohydrates are more oxygen-efficient / yield ATP more quickly than fats. Award [1] for mentioning the 'crossover concept' or shift in muscle fiber recruitment (fast-twitch fibers rely more on carbs). (b) Award up to [7] marks total: Award [1] for stating dehydration reduces plasma/blood volume. Award [1] for stating reduced blood volume decreases stroke volume and venous return. Award [1] for explaining the compensatory increase in heart rate (cardiovascular drift). Award [1] for noting the potential decrease in cardiac output and oxygen transport. Award [1] for stating that skin blood flow / peripheral vasodilation is reduced. Award [1] for stating that sweat rate decreases. Award [1] for explaining that reduced skin blood flow and sweat rate impair evaporative/convective cooling, leading to elevated core body temperature. (c) Award up to [9] marks total: Award up to [3] marks for 'Before' strategies (e.g., carbohydrate loading to maximize glycogen [1], pre-event meal characteristics [1], pre-hydration guidelines [1]). Award up to [3] marks for 'During' strategies (e.g., carbohydrate intake rates of 30-90g/hr [1], regular fluid consumption to avoid >2% mass loss [1], inclusion of sodium/electrolytes to maintain osmotic drive and prevent hyponatremia/cramping [1]). Award up to [3] marks for 'After' strategies (e.g., rehydration volume of 1.25-1.5 L per kg of weight lost [1], high-glycemic carbohydrates immediately for rapid glycogen resynthesis [1], protein intake of 20-25g for muscle repair [1]).