2023 IB DP Sports, Exercise and Health Science Practice Paper with Answers

(a) At Stage 3, the blood lactate concentration of the recreational rowers is 3.5 mmol/L.

(b) Distinguishing heart rate responses:
- At submaximal intensities (Stages 1 and 3), elite rowers display a lower heart rate than recreational rowers (110 vs 125 bpm, and 145 vs 165 bpm respectively).
- At maximal intensity (Stage 5), elite rowers reach a slightly higher maximum heart rate than recreational rowers (188 bpm vs 185 bpm).
- Both groups exhibit a linear increase in heart rate as exercise intensity increases from Stage 1 to Stage 5.

(c) Physiological explanation for lower lactate at Stage 3:
- Elite rowers have a higher capillary density in active skeletal muscle, which enhances oxygen delivery and facilitates more rapid removal of metabolic by-products.
- They possess a higher mitochondrial density and greater concentration of aerobic enzymes, which increases their capacity for aerobic ATP production and reduces reliance on anaerobic glycolysis at submaximal intensities.
- Elite rowers have more efficient lactate clearance mechanisms (e.g., higher abundance of monocarboxylate transporters - MCTs).
- This delays the onset of blood lactate accumulation (OBLA) to a higher absolute workload compared to recreational rowers.

(d) \(VO_{2}max\) concept and adaptations:
- Concept (1.5 marks): \(VO_{2}max\) represents the maximum volume of oxygen that an individual can intake, transport, and utilize per unit of time during incremental exhaustive exercise.
- Cardiovascular adaptations (3 marks - 1 mark for each of three outlined):
1. Cardiac hypertrophy (specifically of the left ventricle), which increases stroke volume, allowing more oxygenated blood to be pumped per beat.
2. Increased capillary density around skeletal muscle fibers, which decreases diffusion distance and increases the surface area for gas exchange.
3. Increased total blood volume and red blood cell count (hemoglobin mass), which elevates the oxygen-carrying capacity of the blood.

(a) [1 mark max]
- Award 1 mark for identifying 3.5 mmol/L (accept "3.5").

(b) [3 marks max]
- Award 1 mark for stating elite rowers have lower HR at submaximal stages (Stages 1/3).
- Award 1 mark for stating elite rowers achieve higher/similar HR at maximal stage (Stage 5).
- Award 1 mark for identifying that both show a progressive/linear increase with workload.

(c) [4 marks max]
- Award 1 mark for mentioning higher capillary density (improves O2 delivery/lactate removal).
- Award 1 mark for mentioning higher mitochondrial density/aerobic enzymes (increases aerobic ATP synthesis capacity).
- Award 1 mark for pointing out decreased reliance on anaerobic glycolysis (less lactate produced at a given workload).
- Award 1 mark for mentioning improved lactate clearance/shuttling capacity (MCTs) or delay of OBLA/lactate threshold.

(d) [4.5 marks max]
- Award 1.5 marks for a complete definition of \(VO_{2}max\) (must include intake/transport, utilization, and maximum/limits).
- Award 1 mark each for any three chronic cardiovascular adaptations up to 3 marks:
- Increased left ventricular volume/stroke volume (cardiac hypertrophy).
- Increased skeletal muscle capillarization.
- Increased blood volume/red blood cell/hemoglobin volume.
- Increased arterio-venous oxygen difference (\((a-v)O_{2}\,diff\)).

(a) The Random Practice Group achieved the highest score during the 24-hour retention test, with a score of 7.4.

(b) Performance changes:
- The Blocked practice group showed a significant drop in serving performance from post-practice (8.2) to the retention test (4.5).
- The Random practice group showed an improvement in performance from post-practice (6.1) to the retention test (7.4).

(c) Contextual interference explanation:
- Contextual interference refers to the memory and performance disruption that results from performing multiple skills or variations of a skill within a single practice session.
- Blocked practice represents a low contextual interference environment. It allows the learner to hold the motor program in short-term/working memory, leading to rapid, immediate performance gains during the acquisition phase (score of 8.2).
- However, because low contextual interference requires minimal cognitive processing, it does not promote strong, long-term memory representation, resulting in poor performance on the retention test (score of 4.5).
- Random practice represents a high contextual interference environment. It forces the learner to continually reconstruct the action plan or retrieve the correct motor program from long-term memory on each successive trial, which impairs short-term performance during acquisition (score of 6.1).
- This deeper, more active cognitive effort/elaboration process leads to stronger, more stable neural pathways, which ultimately yields superior motor learning and high retention scores (7.4).

(d) Comparison of stages and feedback:
- Cognitive stage characteristics (1 mark): The beginner makes frequent, large errors; movements lack fluidity; the performer must consciously think about every element of the skill.
- Autonomous stage characteristics (1 mark): The elite performer executes movements automatically with minimal conscious thought; performance is consistent, highly accurate, and fluent.
- Role of Feedback (2.5 marks):
- In the cognitive stage, the performer lacks the internal sensory references to evaluate their own performance, and thus relies heavily on external (extrinsic) feedback, such as a coach's advice (knowledge of performance) or visual outcome (knowledge of results).
- In the autonomous stage, the performer has developed a strong internal sensory model, allowing them to rely primarily on internal (intrinsic/kinesthetic) feedback to detect and self-correct errors in real-time.

(a) [1 mark max]
- Award 1 mark for identifying the "Random Practice Group" (or "Random Group").

(b) [2 marks max]
- Award 1 mark for describing the decrease in the Blocked group's performance.
- Award 1 mark for describing the increase/improvement in the Random group's performance.

(c) [5 marks max]
- Award 1 mark for defining/defining the role of contextual interference.
- Award 1 mark for linking Blocked practice to low contextual interference and explaining its short-term working-memory advantage (high acquisition score).
- Award 1 mark for linking Blocked practice to poor long-term motor-schema consolidation (low retention score).
- Award 1 mark for linking Random practice to high contextual interference and explaining why it disrupts immediate performance (reconstruction/retrieval effort).
- Award 1 mark for explaining that the high cognitive effort/elaboration in random practice builds stronger, more adaptable memory representation (high retention score).

(d) [4.5 marks max]
- Award 1 mark for correctly describing the cognitive stage (errors, conscious focus).
- Award 1 mark for correctly describing the autonomous stage (automaticity, consistency).
- Award 2.5 marks for contrasting the feedback shift: detail how the cognitive stage relies on extrinsic feedback (KP/KR) because internal sensory models are undeveloped, whereas the autonomous stage relies heavily on intrinsic/proprioceptive feedback for real-time adjustments.

(a) The angle of release that yielded the greatest horizontal distance is 40° (resulting in 20.8 m).

(b) Description of the relationship:
- As the angle of release increases from 30° to 40°, there is a progressive increase in the horizontal distance achieved (from 18.5 m to 20.8 m).
- The peak performance occurs at 40°.
- As the angle of release increases further from 40° to 50°, the horizontal distance achieved decreases progressively (from 20.8 m down to 18.6 m).
- This demonstrates a non-linear, parabolic relationship between the release angle and distance.

(c) Explanation of optimal release angle:
- In theoretical projectile motion where the release height and landing height are equal, the optimal angle of release to maximize horizontal displacement is exactly 45°.
- In shot put, the implement is released from a height well above the landing surface (ground level), resulting in a positive relative release height.
- A positive release height increases the flight time of the projectile because it has further to fall.
- Because of this extra flight time, the vertical velocity component does not need to be as high to keep the shot airborne. Therefore, to maximize horizontal distance, the athlete can dedicate more of their total release velocity to the horizontal vector, lowering the optimal release angle to below 45° (typically between 37° and 42° depending on release height).

(d) Application of Newton's Laws:
- Newton's First Law (Law of Inertia) (1.5 marks): The shot put will remain at rest in the athlete's hand until acted upon by an external unbalanced force (muscular force applied during the glide/spin). Once released, it would continue in a straight line at a constant speed, but external forces (gravity and air resistance) act to pull it down and slow it down.
- Newton's Second Law (Law of Acceleration) (1.5 marks): The acceleration of the shot put is directly proportional to the force applied to it and inversely proportional to its mass (\(F = ma\)). Since the mass of the shot is constant, applying a greater muscular force results in a higher acceleration and velocity of release, maximizing distance.
- Newton's Third Law (Law of Action-Reaction) (2 marks): For every action, there is an equal and opposite reaction. When the athlete forcefully plants their foot and pushes backward and downward against the throwing circle, the ground exerts an equal and opposite reaction force (ground reaction force) upward and forward through the athlete's kinetic chain, which is transferred into the shot put.

(a) [1 mark max]
- Award 1 mark for stating 40° (or 40 degrees).

(b) [2.5 marks max]
- Award 1 mark for stating that distance increases up to 40°.
- Award 1 mark for stating that distance decreases beyond 40°.
- Award 0.5 marks for recognizing 40° as the optimal angle/peak within this dataset.

(c) [4 marks max]
- Award 1 mark for stating 45° is optimal when release and landing heights are equal.
- Award 1 mark for stating the shot put is released above ground level (positive relative release height).
- Award 1 mark for explaining that positive release height increases the flight time of the shot.
- Award 1 mark for explaining that increased flight time allows a greater horizontal velocity component to be prioritized, resulting in a lower optimal angle (less than 45°).

(d) [5 marks max]
- Award 1.5 marks for applying Newton's First Law (inertia of the static shot, change of state by muscular force, role of gravity/air resistance post-release).
- Award 1.5 marks for applying Newton's Second Law (\(F=ma\), linking muscular force to acceleration/release velocity of a constant mass).
- Award 2 marks for applying Newton's Third Law (action of pushing against the ground, reaction of ground reaction force channeled up through the body to the shot put).

(a) The EMG activity of the Biceps Femoris during the eccentric phase is 22% MVIC.

(b) Distinguishing contractions:
- Eccentric phase: The Rectus Femoris performs an eccentric contraction. This occurs when the muscle develops tension and actively lengthens to decelerate the downward movement of the body and control the descent.
- Concentric phase: The Rectus Femoris performs a concentric contraction. This occurs when the muscle develops tension and actively shortens to overcome gravity and push the body upward into extension.
- Both are types of isotonic (dynamic) muscle contractions, but they differ in direction of movement and function (controlling gravity vs. overcoming gravity).

(c) Sliding filament theory:
- An action potential arrives at the neuromuscular junction, travels down the T-tubules, and triggers the release of Calcium ions (\(Ca^{2+}\)) from the sarcoplasmic reticulum into the sarcoplasm.
- Calcium ions bind to the protein troponin on the thin actin filament.
- This binding causes a conformational change in troponin, which shifts tropomyosin away from the active myosin-binding sites on the actin filament, exposing them.
- Energized myosin heads (carrying ADP and inorganic phosphate) bind to the newly exposed active sites on actin, forming a cross-bridge.
- The release of ADP and phosphate triggers the "power stroke," where the myosin head pivots and pulls the actin filament toward the center of the sarcomere (M-line), shortening the sarcomere.
- A new ATP molecule binds to the myosin head, causing it to detach from the actin filament. The ATP is then hydrolyzed (into ADP and Pi) by myosin ATPase, resetting the myosin head so the cycle can repeat as long as calcium and ATP are present.

(d) Comparison of muscle fiber types:
- Structural Differences (1.5 marks):
- Type I (Slow Twitch) fibers have high mitochondrial density, high capillary density, and high myoglobin content (making them red).
- Type IIb (Fast Glycolytic) fibers have low mitochondrial and capillary density, low myoglobin content (making them white), but high glycogen storage and a highly developed sarcoplasmic reticulum.
- Functional Differences (2 marks):
- Type I fibers have high fatigue resistance, low contraction speed, low force production, and rely primarily on aerobic ATP production.
- Type IIb fibers have low fatigue resistance (fatigue rapidly), very fast contraction speed, high force production, and rely primarily on anaerobic glycolytic and ATP-PC systems.

(a) [1 mark max]
- Award 1 mark for stating 22% MVIC (accept "22").

(b) [3 marks max]
- Award 1 mark for describing eccentric contraction (lengthening under tension / controlling descent).
- Award 1 mark for describing concentric contraction (shortening under tension / generating upward force).
- Award 1 mark for showing a clear point of comparison/distinction (e.g., direction of motion or role against gravity).

(c) [5 marks max]
- Award 1 mark for mentioning the release of calcium ions from the sarcoplasmic reticulum.
- Award 1 mark for explaining calcium binding to troponin, causing tropomyosin to shift and expose actin active sites.
- Award 1 mark for explaining cross-bridge formation (myosin head binding to actin).
- Award 1 mark for describing the power stroke (myosin pulling actin toward the center of the sarcomere).
- Award 1 mark for explaining the role of ATP in detachment and resetting/hydrolysis of the myosin head.

(d) [3.5 marks max]
- Award up to 1.5 marks for structural comparisons (mitochondria, capillaries, myoglobin, glycogen).
- Award up to 2 marks for functional comparisons (fatigue resistance, force capacity, speed of contraction, primary metabolic pathway/energy system).

Part (a): Acetylcholine (ACh) is a neurotransmitter released from the motor neuron axon terminal across the synaptic cleft. It binds to nicotinic receptors on the motor end plate of the sarcolemma, causing depolarization by allowing sodium ions to enter. This action potential propagates along the sarcolemma and down the T-tubules. The depolarizing signal triggers the release of calcium ions (\(Ca^{2+}\)) from the sarcoplasmic reticulum into the sarcoplasm. Calcium ions bind to troponin, causing a conformational change that pulls tropomyosin away from the active binding sites on actin. This exposes the myosin-binding sites, allowing the myosin heads to bind and form cross-bridges, initiating the power stroke and contraction. Part (b): Slow twitch (Type I) fibers have high myoglobin content, high capillary density, and a high density of mitochondria (structural), which support high aerobic capacity, high fatigue resistance, and a slow contraction velocity (functional). Fast twitch (Type IIx) fibers have low myoglobin content, low capillary density, and fewer mitochondria (structural), but contain high stores of glycogen and phosphocreatine. Functionally, Type IIx fibers possess high anaerobic/glycolytic capacity, fast contraction speed, high force generation, but fatigue very rapidly. Part (c): Reciprocal inhibition is the process where muscles on one side of a joint relax (antagonist) to accommodate the contraction of muscles on the other side (agonist), mediated by inhibitory interneurons in the spinal cord. During the preparatory (downward) phase of a vertical jump, the hips and knees flex. The gluteus maximus (hip extensor) and quadriceps (knee extensor) contract eccentrically to control the rate of descent against gravity. During the upward (take-off) phase, explosive hip and knee extension occurs. The gluteus maximus and quadriceps act as agonists (contracting concentrically), while the hip flexors (iliopsoas) and knee flexors (hamstrings) act as antagonists. Reciprocal inhibition prevents the antagonists from resisting the movement, facilitating maximum concentric force and speed of extension.

Part (a) [Max 6 marks]: Award 1 mark for each point outlined: release of ACh across the synaptic cleft; binding of ACh to sarcolemma receptors causing depolarization/action potential; action potential travel down T-tubules; release of calcium from the sarcoplasmic reticulum; binding of calcium to troponin; shifting of tropomyosin to expose actin active sites; cross-bridge formation. Part (b) [Max 6 marks]: Award up to 3 marks for structural comparisons (e.g., mitochondria, capillaries, myoglobin) and up to 3 marks for functional comparisons (e.g., fatigue resistance, contraction speed, ATP source, force output). Must clearly contrast Type I and Type IIx to receive full marks. Part (c) [Max 8 marks]: Award 2 marks for a clear definition/explanation of reciprocal inhibition (motor neurons exciting agonist while simultaneously inhibiting antagonist). Award 3 marks for the preparatory phase analysis (identifying joint flexion, eccentric contraction of extensors to control gravity, and coordination). Award 3 marks for the upward phase analysis (identifying concentric contraction of agonists [quadriceps and gluteus maximus], relaxation of antagonists [hamstrings/iliopsoas] via reciprocal inhibition to allow rapid, powerful extension).

Part (a): The Atkinson and Shiffrin model consists of three distinct stores: sensory memory, short-term memory (STM), and long-term memory (LTM). Sensory memory receives environmental stimuli (e.g., the flight of a ball) and holds it for a fraction of a second with unlimited capacity but rapid decay. If selective attention is applied, the relevant information is transferred to the STM. STM has a limited capacity (\(7 \pm 2\) items) and duration (approx. 20-30 seconds). For a novice, STM is easily overloaded because they struggle to filter out irrelevant background noise. Information must be rehearsed (mental or physical practice) to be encoded and transferred into LTM, which has unlimited capacity and duration. Retrieved skills are recalled from LTM to STM for execution. Part (b): In the cognitive stage of learning, the novice relies heavily on extrinsic feedback (provided by coaches or visual aids) because they lack an internal sensory blueprint of the movement. They depend on knowledge of results (KR) to understand the outcome of their action, and simple, descriptive knowledge of performance (KP) to establish basic movement patterns. As they progress to the autonomous stage, their internal kinesthetic awareness (proprioceptors) improves significantly, allowing them to rely predominantly on intrinsic feedback (sensory feeling of the movement) to detect and correct errors. Extrinsic feedback becomes highly specific, technical, and supplementary. They use sophisticated KP to fine-tune mechanics and require less frequent KR since they can self-assess outcomes instantly. Part (c): For a closed, discrete skill (e.g., a golf putt), fixed practice is highly effective as it allows replication of the exact movement under identical conditions to groove the motor program. Massed practice can be effective for highly motivated athletes, but distributed practice is often preferred to maintain focus. For an open, continuous skill (e.g., dribbling in soccer during a match), variable practice is essential because the environment changes constantly, requiring the development of a flexible schema. Distributed practice is optimal here to manage high physical and cognitive demands, allowing intervals for feedback and recovery.

Part (a) [Max 6 marks]: Award up to 2 marks for describing sensory memory and the role of selective attention. Award up to 2 marks for describing short-term memory (capacity, duration, novice vulnerability to overload). Award up to 2 marks for describing long-term memory (unlimited capacity/duration, encoding, and retrieval process). Part (b) [Max 8 marks]: Award up to 4 marks for explaining feedback in the cognitive stage (reliance on extrinsic feedback due to weak internal model; heavy reliance on KR to judge outcome; basic KP to form cognitive schema). Award up to 4 marks for explaining feedback in the autonomous stage (dominance of intrinsic feedback/proprioception; ability to self-correct; extrinsic feedback is highly technical/specific; focus on detailed KP; decreased reliance on immediate external KR). Part (c) [Max 6 marks]: Award up to 3 marks for discussing the closed, discrete skill (defining/characterizing the skill, justifying fixed practice to build consistency, addressing massed/distributed suitability). Award up to 3 marks for discussing the open, continuous skill (characterizing the dynamic nature, justifying variable practice to build schema/adaptability, justifying distributed practice to manage cognitive load/fatigue).