PHE · Topic 7.1
Exercise Physiology and Training Design
At Year 4 Advanced, PHE demands physiological justification for training choices. You must understand the energy systems and muscle fibre types relevant to specific sports and link these to training methods with evidence. Evaluating the strengths and limitations of training approaches is essential.
What You'll Learn
- Distinguish the aerobic, anaerobic lactic (glycolytic), and ATP-PC (phosphocreatine) energy systems
- Compare Type I and Type II muscle fibres and link each to specific sports
- Define VO&sub2; max and explain its significance as a measure of aerobic fitness
- Design a periodised training programme using FITT principles and SMART goals
- Justify training method choices with physiological reasoning
- Evaluate training programmes for strengths, limitations, and individual suitability
IB Assessment Focus
Criterion A: Demonstrate understanding of physiological concepts; apply them to specific athletes and sports.
Criterion B: Collect and process fitness data; design a training investigation with clear variables and protocols.
Criterion C: Communicate training programmes clearly; use correct physiological terminology throughout.
Criterion D: Evaluate the effectiveness of training programmes; discuss limitations; reflect on ethical considerations in sport science.
Key Vocabulary
| Term | Definition |
|---|---|
| ATP | Adenosine triphosphate — the immediate energy currency of all cells; must be resynthesised continuously during exercise |
| Aerobic energy system | Produces ATP using oxygen; oxidises carbohydrates and fats; used for prolonged, lower-intensity activity |
| Anaerobic lactic system | Produces ATP from glucose without oxygen; lactic acid is a byproduct; used for 30 sec – 3 min high-intensity effort |
| ATP-PC system | Immediate energy system using phosphocreatine (PC) stores; maximum power for <10 seconds; no lactic acid |
| VO&sub2; max | Maximum rate at which the body can consume oxygen during maximal exercise; the gold standard of aerobic fitness |
| Periodisation | Systematic organisation of training into phases (macrocycle, mesocycle, microcycle) to optimise performance and prevent overtraining |
| FITT principles | Frequency, Intensity, Time, Type — the four variables used to specify a training programme |
PHE · Topic 7.1
Energy Systems
The body uses three energy systems, not one. They operate simultaneously but with different systems dominant depending on exercise intensity and duration. Understanding which system is dominant for a given sport justifies training design at Year 4 Advanced.
The Three Energy Systems
| System | Duration | O&sub2; needed? | Byproduct | Intensity | Example activity |
|---|---|---|---|---|---|
| ATP-PC (phosphocreatine) | 0–10 seconds | No | None (clean) | Maximum | 100m sprint; shot put; jumping |
| Anaerobic lactic (glycolytic) | 10 sec – 3 min | No | Lactic acid (causes fatigue) | High | 400m run; 200m swim; 1 min rowing |
| Aerobic (oxidative) | 3 min – hours | Yes | CO&sub2; and H&sub2;O | Moderate–low | Marathon; cycling; distance swimming |
All systems operate simultaneously:
Energy systems are not exclusive. At the start of any exercise, the ATP-PC system dominates. As it is depleted (<10 seconds), the anaerobic lactic system takes over. If exercise continues at lower intensity, the aerobic system increasingly dominates. The proportion contributed by each system depends on exercise intensity and duration. This is why training must target the specific system used in competition.
Energy systems are not exclusive. At the start of any exercise, the ATP-PC system dominates. As it is depleted (<10 seconds), the anaerobic lactic system takes over. If exercise continues at lower intensity, the aerobic system increasingly dominates. The proportion contributed by each system depends on exercise intensity and duration. This is why training must target the specific system used in competition.
Critical Rule: Lactic acid production causes the burning sensation and fatigue during high-intensity anaerobic exercise. However, lactic acid is not a "waste product" — it is a fuel. The liver and heart can convert it to glucose (Cori cycle). The problem is the associated hydrogen ions (H♠) that lower pH and inhibit muscle enzyme function, causing fatigue.
PHE · Topic 7.1
Muscle Fibre Types
Skeletal muscles contain different fibre types with different characteristics. The proportions of each type are largely genetically determined, which partly explains why some athletes are naturally suited to power sports and others to endurance sports.
Type I vs Type II Muscle Fibres
| Feature | Type I (Slow-twitch) | Type II (Fast-twitch) |
|---|---|---|
| Speed of contraction | Slow | Fast |
| Energy system used | Aerobic (oxidative) | Anaerobic (glycolytic/ATP-PC) |
| Fatigue resistance | High — very fatigue-resistant | Low — fatigue quickly |
| Power output | Low power | High power |
| Myoglobin content | High (red colour) | Low (pale colour) |
| Mitochondria density | High (aerobic capacity) | Low |
| Best suited for | Endurance: marathon, triathlon, distance cycling | Power and speed: sprinting, weightlifting, jumping |
Practical implication for training:
A 100m sprinter needs to train Type II fibres (high-intensity, short-duration efforts: plyometrics, resistance training, short sprints). A marathon runner needs to develop Type I fibres and aerobic capacity (long slow runs, tempo runs). A 400m runner requires significant development of BOTH types, since the event uses both the ATP-PC/anaerobic lactic system (explosive speed) and the aerobic system (for pace maintenance and recovery). Training design must match fibre type requirements.
A 100m sprinter needs to train Type II fibres (high-intensity, short-duration efforts: plyometrics, resistance training, short sprints). A marathon runner needs to develop Type I fibres and aerobic capacity (long slow runs, tempo runs). A 400m runner requires significant development of BOTH types, since the event uses both the ATP-PC/anaerobic lactic system (explosive speed) and the aerobic system (for pace maintenance and recovery). Training design must match fibre type requirements.
PHE · Topic 7.1
VO&sub2; max and Fitness Assessment
VO&sub2; max (maximum oxygen uptake) is the gold standard measure of aerobic fitness. It quantifies the body's capacity to transport and use oxygen during maximal exercise. At Year 4, you must understand how to assess fitness and evaluate the limitations of each method.
VO&sub2; max
VO&sub2; max = maximum volume of O&sub2; consumed per minute (mL/kg/min)Higher values = greater aerobic capacity
Typical VO&sub2; max Values
| Population | VO&sub2; max (mL/kg/min) |
|---|---|
| Sedentary adult male | ~35–40 |
| Fit adult male | ~45–55 |
| Elite marathon runner | ~70–80 |
| World-class cyclist (e.g., Indurain) | ~88 |
Fitness Assessment Methods
| Test | What it measures | Strength | Limitation |
|---|---|---|---|
| Multi-stage fitness test (bleep test) | Aerobic capacity (predicted VO&sub2; max) | Simple, inexpensive, can test large groups | Predicted (not measured); requires maximum effort; affected by motivation; surface conditions affect results |
| Harvard step test | Cardiovascular fitness (heart rate recovery) | Simple equipment; measures recovery rate | Doesn't directly measure VO&sub2; max; step height not adjusted for body size |
| Laboratory VO&sub2; max test (treadmill with gas analysis) | Direct VO&sub2; max measurement | Most accurate; direct measurement | Expensive; requires lab equipment; requires medical supervision; not practical for field use |
| Cooper 12-minute run | Distance covered = aerobic capacity estimate | Simple field test; no equipment | Motivation affects result; weather and terrain influence distance; indirect estimate only |
PHE · Topic 7.1
Training Design — Periodisation and FITT
Effective training is systematic, not random. Periodisation organises training into phases to ensure peak performance at the right time while preventing overtraining. FITT principles specify the precise variables of each training session.
FITT Principles
| Variable | Meaning | Example specification |
|---|---|---|
| Frequency | How often you train | 4 sessions per week |
| Intensity | How hard you train (% max HR, RPE, % 1RM) | 70–80% maximum heart rate |
| Time | Duration of each session | 45 minutes per session |
| Type | What kind of training | Interval running for aerobic base |
Periodisation Structure
- Macrocycle: The overall training year (12 months) with a specific peak competition target.
- Mesocycle: A training block of 4–6 weeks with a specific focus (base fitness, strength, power, taper).
- Microcycle: A single week of training with specific sessions planned.
| Phase | Focus | Intensity / Volume |
|---|---|---|
| Off-season / Base | General fitness, aerobic base, injury recovery | High volume, low intensity |
| Pre-season / Build | Sport-specific fitness, strength, speed | Increasing intensity, moderate volume |
| In-season / Peak | Maintaining fitness, performance peaks | High intensity, reduced volume |
| Taper | Pre-competition recovery: reduce fatigue while maintaining fitness | 40–60% volume reduction; maintain intensity |
SMART Goals in training:
Specific — "Improve 400m time" not "run faster"
Measurable — "from 58 seconds to 55 seconds"
Achievable — realistic for the athlete's current level
Relevant — linked to the athlete's sport and priority
Time-bound — "within 12 weeks of the training programme"
Specific — "Improve 400m time" not "run faster"
Measurable — "from 58 seconds to 55 seconds"
Achievable — realistic for the athlete's current level
Relevant — linked to the athlete's sport and priority
Time-bound — "within 12 weeks of the training programme"
Critical Rule: When justifying a training programme, always link the choice of methods to the energy systems and muscle fibre types relevant to the sport. Saying "interval training improves fitness" is insufficient. "Interval training at 85–90% max HR develops the anaerobic lactic system and increases the lactate threshold, which is the primary limiting factor for a 400m runner's performance" earns marks at Year 4.
PHE · Topic 7.1
Worked Examples
Extended responses showing Year 4 physiological justification.
EXAMPLE 1Design and justify a 6-week training programme for a 400m runner.
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Full Solution
A 400m runner requires both aerobic (sustained pace) and anaerobic lactic (final kick, speed maintenance) energy systems, and both Type II fast-twitch (explosive speed) and Type I (fatigue resistance) muscle fibres.
Weeks 1–2 (Base phase): 3 × continuous runs at 60–70% max HR, 20–30 minutes. Justification: builds aerobic base and cardiovascular efficiency; develops Type I fibres and oxygen delivery capacity; at this intensity, lactic acid production is minimal, allowing high training volume without fatigue accumulation.
Weeks 3–4 (Build phase): 2 × interval sessions (400m repeats at 85–90% max HR, 2-minute rest between) + 1 × tempo run (3km at 75% max HR). Justification: 400m intervals at near-race intensity directly target the anaerobic lactic system, increasing lactate threshold; tempo run maintains aerobic base; 2-min rest allows partial (not full) recovery — training the ability to tolerate lactate accumulation.
Week 5 (Race-specific): 300m efforts at race pace; one practice race. Justification: simulates race demands; develops pacing strategy; activates ATP-PC system for explosive start.
Week 6 (Taper): Reduce volume by 40%, maintain intensity. 2 × short interval sessions (3 × 200m at race pace). Justification: reduces fatigue accumulation while maintaining neuromuscular activation and fitness adaptations; ensures peak performance at competition.
SMART goal: Improve 400m time from [current time] to sub-[target time] within 6 weeks of the programme. Measured at Weeks 1 and 6.
Weeks 1–2 (Base phase): 3 × continuous runs at 60–70% max HR, 20–30 minutes. Justification: builds aerobic base and cardiovascular efficiency; develops Type I fibres and oxygen delivery capacity; at this intensity, lactic acid production is minimal, allowing high training volume without fatigue accumulation.
Weeks 3–4 (Build phase): 2 × interval sessions (400m repeats at 85–90% max HR, 2-minute rest between) + 1 × tempo run (3km at 75% max HR). Justification: 400m intervals at near-race intensity directly target the anaerobic lactic system, increasing lactate threshold; tempo run maintains aerobic base; 2-min rest allows partial (not full) recovery — training the ability to tolerate lactate accumulation.
Week 5 (Race-specific): 300m efforts at race pace; one practice race. Justification: simulates race demands; develops pacing strategy; activates ATP-PC system for explosive start.
Week 6 (Taper): Reduce volume by 40%, maintain intensity. 2 × short interval sessions (3 × 200m at race pace). Justification: reduces fatigue accumulation while maintaining neuromuscular activation and fitness adaptations; ensures peak performance at competition.
SMART goal: Improve 400m time from [current time] to sub-[target time] within 6 weeks of the programme. Measured at Weeks 1 and 6.
EXAMPLE 2Explain why a marathon runner and a 100m sprinter require fundamentally different training programmes.
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Full Solution
Energy systems: A 100m sprinter completes the event in ~10 seconds entirely on the ATP-PC system (maximum intensity, no lactic acid). A marathon runner (2+ hours) relies almost entirely on the aerobic system, oxidising carbohydrates and fats with oxygen.
Muscle fibres: A sprinter needs highly developed Type II fast-twitch fibres (powerful, fast-contracting, anaerobic). A marathon runner needs highly developed Type I slow-twitch fibres (fatigue-resistant, aerobic, low-power but sustainable).
Sprinter's training: Plyometrics, heavy resistance training (squats, cleans), short sprint drills (<60m at maximum effort), power development. Justification: develops neuromuscular power, explosive ATP-PC energy capacity, and Type II fibre recruitment patterns.
Marathon runner's training: Long slow distance runs (LSDs) at 60–70% max HR (3–30km); tempo runs at 75–80% max HR; weekly mileage of 80–160km. Justification: develops aerobic enzyme density, mitochondrial density, fat oxidation capacity, and cardiac stroke volume — all in service of the aerobic system.
Overlap: Neither uses zero of the "other" system, but the training emphasis is fundamentally different because the physiological demands are opposite.
Muscle fibres: A sprinter needs highly developed Type II fast-twitch fibres (powerful, fast-contracting, anaerobic). A marathon runner needs highly developed Type I slow-twitch fibres (fatigue-resistant, aerobic, low-power but sustainable).
Sprinter's training: Plyometrics, heavy resistance training (squats, cleans), short sprint drills (<60m at maximum effort), power development. Justification: develops neuromuscular power, explosive ATP-PC energy capacity, and Type II fibre recruitment patterns.
Marathon runner's training: Long slow distance runs (LSDs) at 60–70% max HR (3–30km); tempo runs at 75–80% max HR; weekly mileage of 80–160km. Justification: develops aerobic enzyme density, mitochondrial density, fat oxidation capacity, and cardiac stroke volume — all in service of the aerobic system.
Overlap: Neither uses zero of the "other" system, but the training emphasis is fundamentally different because the physiological demands are opposite.
EXAMPLE 3Evaluate the multi-stage fitness test (bleep test) as a measure of aerobic fitness.
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Full Solution
Strengths: The bleep test is simple to administer, requires minimal equipment (recording, flat surface, cones), can be conducted on large groups simultaneously, is well-validated against laboratory VO&sub2; max measures, and provides a predicted VO&sub2; max score using standardised tables.
Limitations:
1. Indirect measurement: VO&sub2; max is predicted (estimated) rather than directly measured. Prediction introduces error, particularly for individuals at the extremes of fitness.
2. Motivation-dependent: The test requires maximal effort; results are significantly affected by the participant's willingness to push to true maximum. Unmotivated participants will score lower than their physiological maximum.
3. Surface sensitivity: Test surface (grass, gymnasium floor, outdoor track) affects running mechanics and traction; results are not directly comparable across surfaces.
4. Learning effect: Participants who have done the test before are familiar with the pace structure and may pace better; first-time participants may start too fast and fatigue early.
5. Not sport-specific: For swimmers or cyclists, running-based aerobic tests may underestimate fitness because trained aerobic capacity is partly sport-specific (swimming VO&sub2; max ≠ running VO&sub2; max).
Conclusion: The bleep test is an appropriate and practical field measure for general aerobic fitness in school or team contexts. For clinical accuracy or research, direct laboratory VO&sub2; max measurement is superior despite its cost and complexity.
Limitations:
1. Indirect measurement: VO&sub2; max is predicted (estimated) rather than directly measured. Prediction introduces error, particularly for individuals at the extremes of fitness.
2. Motivation-dependent: The test requires maximal effort; results are significantly affected by the participant's willingness to push to true maximum. Unmotivated participants will score lower than their physiological maximum.
3. Surface sensitivity: Test surface (grass, gymnasium floor, outdoor track) affects running mechanics and traction; results are not directly comparable across surfaces.
4. Learning effect: Participants who have done the test before are familiar with the pace structure and may pace better; first-time participants may start too fast and fatigue early.
5. Not sport-specific: For swimmers or cyclists, running-based aerobic tests may underestimate fitness because trained aerobic capacity is partly sport-specific (swimming VO&sub2; max ≠ running VO&sub2; max).
Conclusion: The bleep test is an appropriate and practical field measure for general aerobic fitness in school or team contexts. For clinical accuracy or research, direct laboratory VO&sub2; max measurement is superior despite its cost and complexity.
PHE · Topic 7.1
Practice Q&A
Attempt each question before revealing the model answer. Use precise physiological terminology.
IDENTIFYWhich energy system does a 100m sprinter primarily use? Justify.
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Model Answer
The ATP-PC (phosphocreatine) system. A 100m sprint takes approximately 10 seconds at maximum intensity. The ATP-PC system is the only energy system capable of providing ATP fast enough for maximum-intensity exercise. It uses stored phosphocreatine (PC) to immediately resynthesise ATP without oxygen and without producing lactic acid. PC stores are depleted within approximately 8–10 seconds — exactly matching the duration of the event. The anaerobic lactic system contributes increasingly if the effort extends beyond 10 seconds.
COMPARECompare Type I and Type II muscle fibres for a basketball player.
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Model Answer
Basketball requires both fibre types: Type II (fast-twitch) for explosive actions (jumping, sprinting, cutting, throwing) — these provide rapid, powerful ATP production via the anaerobic system; and Type I (slow-twitch) for sustained movement across the court throughout a 40-minute game — these provide fatigue-resistant aerobic energy for continued activity.
A basketball player should train both: plyometrics and sprint intervals for Type II development; aerobic conditioning (continuous running, interval circuits) for Type I and cardiovascular efficiency. The balance depends on position: a point guard needs high aerobic capacity for continuous movement; a power forward needs explosive strength for rebounding.
A basketball player should train both: plyometrics and sprint intervals for Type II development; aerobic conditioning (continuous running, interval circuits) for Type I and cardiovascular efficiency. The balance depends on position: a point guard needs high aerobic capacity for continuous movement; a power forward needs explosive strength for rebounding.
DEFINEWhat is VO&sub2; max and why is it the gold standard of aerobic fitness?
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Model Answer
VO&sub2; max is the maximum volume of oxygen the body can consume per minute during maximal exercise, expressed in mL/kg/min. It is the gold standard of aerobic fitness because it directly quantifies the capacity of the oxygen delivery and utilisation system: the heart's ability to pump oxygenated blood, the lungs' gas exchange efficiency, the muscles' ability to extract and use oxygen aerobically. A higher VO&sub2; max allows higher sustainable exercise intensity, directly predicting endurance performance in most aerobic sports.
JUSTIFYWhy does a taper phase reduce training volume but maintain intensity?
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Model Answer
A taper reduces training volume (typically 40–60%) before competition to allow fatigue to dissipate while maintaining fitness adaptations. Fatigue accumulated during heavy training impairs performance; reducing volume in the final 1–2 weeks allows the body to repair, replenish glycogen stores, and restore neuromuscular function to maximum. Intensity is maintained (not reduced) because:
1. High-intensity stimulus is needed to maintain the neuromuscular adaptations (fast-twitch fibre recruitment patterns, enzyme activity) that training has developed.
2. Dropping intensity would cause detraining of power and speed within days.
Research shows a taper of 7–21 days improves performance by 2–3% in most sports — enough to distinguish podium finishes at elite level.
1. High-intensity stimulus is needed to maintain the neuromuscular adaptations (fast-twitch fibre recruitment patterns, enzyme activity) that training has developed.
2. Dropping intensity would cause detraining of power and speed within days.
Research shows a taper of 7–21 days improves performance by 2–3% in most sports — enough to distinguish podium finishes at elite level.
DESIGNWrite a SMART goal for a swimmer wanting to improve their 100m freestyle time.
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Model Answer
SMART goal: "I will improve my 100m freestyle time from 1:12.4 to under 1:08.0 within 10 weeks, as measured by two timed trials at the start and end of the programme, training 5 sessions per week including 2 interval sessions and 3 technique/endurance sessions."
Specific: 100m freestyle; from 1:12.4 to under 1:08.0.
Measurable: Timed trials at Weeks 1 and 10.
Achievable: 4.4-second improvement over 10 weeks is demanding but realistic for a trained swimmer.
Relevant: Directly linked to competitive swimming performance.
Time-bound: 10-week programme with defined end-point measurement.
Specific: 100m freestyle; from 1:12.4 to under 1:08.0.
Measurable: Timed trials at Weeks 1 and 10.
Achievable: 4.4-second improvement over 10 weeks is demanding but realistic for a trained swimmer.
Relevant: Directly linked to competitive swimming performance.
Time-bound: 10-week programme with defined end-point measurement.
EVALUATEEvaluate the strengths and limitations of interval training for a football player.
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Model Answer
Football energy demands: Football (soccer) requires repeated sprints, recovery periods, and prolonged activity — both aerobic (maintaining play over 90 minutes) and anaerobic lactic (explosive sprints, tackles) systems are critical.
Strengths of interval training: High-intensity intervals develop the anaerobic lactic system directly, increasing lactate threshold — meaning players can sustain higher intensities before lactic acid impairs performance. Short recovery periods develop the aerobic system's ability to clear lactate between efforts (critical in football's stop-start pattern). Sport-specific intervals (30m sprints, 20-second rests) closely replicate match demands — excellent transfer to performance.
Limitations: High injury risk if volume or intensity is increased too rapidly; repeated high-intensity efforts create significant muscle damage requiring adequate recovery. Does not develop tactical or technical skills simultaneously (unlike small-sided games). Requires motivation to achieve true maximum effort; players often "self-limit" during training. May overtax the anaerobic system if players are in heavy competition periods — periodisation must account for match load.
Conclusion: Interval training is highly effective for football-specific conditioning but must be periodised carefully to avoid overtraining and injury, especially during the competitive season.
Strengths of interval training: High-intensity intervals develop the anaerobic lactic system directly, increasing lactate threshold — meaning players can sustain higher intensities before lactic acid impairs performance. Short recovery periods develop the aerobic system's ability to clear lactate between efforts (critical in football's stop-start pattern). Sport-specific intervals (30m sprints, 20-second rests) closely replicate match demands — excellent transfer to performance.
Limitations: High injury risk if volume or intensity is increased too rapidly; repeated high-intensity efforts create significant muscle damage requiring adequate recovery. Does not develop tactical or technical skills simultaneously (unlike small-sided games). Requires motivation to achieve true maximum effort; players often "self-limit" during training. May overtax the anaerobic system if players are in heavy competition periods — periodisation must account for match load.
Conclusion: Interval training is highly effective for football-specific conditioning but must be periodised carefully to avoid overtraining and injury, especially during the competitive season.
DISCUSSDiscuss the ethical considerations of performance-enhancing drugs in sport.
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Model Answer
Against PEDs: Performance-enhancing drugs (e.g., anabolic steroids, EPO) violate the principle of fair competition — athletes who use them have a physiological advantage over clean competitors. Health risks are significant: anabolic steroids increase cardiovascular disease risk; EPO increases blood viscosity, raising risk of stroke. They can set dangerous expectations for younger athletes. WADA (World Anti-Doping Agency) prohibits them to protect athlete health and competitive integrity.
Counterarguments (philosophical debate): Some argue that the line between permitted training aids (altitude tents, caffeine, specific nutrition protocols) and prohibited drugs is not always principled. Elite sport already involves artificial advantages (genetic testing, altitude training, expensive equipment). Arguments for regulated PED use focus on athlete autonomy and harm minimisation.
Year 4 evaluation: The most defensible position recognises the health and fairness concerns while acknowledging the complexity of where the line is drawn. The key issues are: athlete health and safety; competitive equity; the integrity of sport as a test of human capability; and the effect on youth sport culture. A simplistic "drugs are always wrong" answer does not meet Year 4 standard — evaluating competing principles does.
Counterarguments (philosophical debate): Some argue that the line between permitted training aids (altitude tents, caffeine, specific nutrition protocols) and prohibited drugs is not always principled. Elite sport already involves artificial advantages (genetic testing, altitude training, expensive equipment). Arguments for regulated PED use focus on athlete autonomy and harm minimisation.
Year 4 evaluation: The most defensible position recognises the health and fairness concerns while acknowledging the complexity of where the line is drawn. The key issues are: athlete health and safety; competitive equity; the integrity of sport as a test of human capability; and the effect on youth sport culture. A simplistic "drugs are always wrong" answer does not meet Year 4 standard — evaluating competing principles does.
APPLYWhy might two athletes with identical VO&sub2; max values perform differently in a marathon?
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Model Answer
VO&sub2; max is an important but incomplete predictor of endurance performance. Athletes with identical VO&sub2; max may differ in:
1. Lactate threshold (LT): The intensity at which lactic acid begins to accumulate significantly. An athlete with a higher LT as a percentage of VO&sub2; max can sustain higher pace without fatigue, regardless of VO&sub2; max.
2. Running economy: The oxygen cost of running at a given speed. More economical runners use less oxygen per km, effectively using their VO&sub2; max more efficiently.
3. Glycogen stores: Greater muscle glycogen stores support longer sustained effort before "hitting the wall" (glycogen depletion).
4. Heat tolerance and hydration strategy: Physiological responses to heat stress vary; effective hydration maintains performance.
5. Mental skills: Pacing strategy, pain tolerance, and mental resilience are not captured by VO&sub2; max but significantly affect marathon performance.
Conclusion: VO&sub2; max is one of several physiological determinants of endurance performance; elite marathon performance requires optimising all of these variables simultaneously.
1. Lactate threshold (LT): The intensity at which lactic acid begins to accumulate significantly. An athlete with a higher LT as a percentage of VO&sub2; max can sustain higher pace without fatigue, regardless of VO&sub2; max.
2. Running economy: The oxygen cost of running at a given speed. More economical runners use less oxygen per km, effectively using their VO&sub2; max more efficiently.
3. Glycogen stores: Greater muscle glycogen stores support longer sustained effort before "hitting the wall" (glycogen depletion).
4. Heat tolerance and hydration strategy: Physiological responses to heat stress vary; effective hydration maintains performance.
5. Mental skills: Pacing strategy, pain tolerance, and mental resilience are not captured by VO&sub2; max but significantly affect marathon performance.
Conclusion: VO&sub2; max is one of several physiological determinants of endurance performance; elite marathon performance requires optimising all of these variables simultaneously.
PHE · Review
Flashcard Review
Tap each card to reveal the answer. Try to answer from memory first.
What are the three energy systems?
1. ATP-PC (phosphocreatine): 0–10 sec, maximum intensity, no O&sub2;, no lactic acid.
2. Anaerobic lactic (glycolytic): 10 sec–3 min, high intensity, no O&sub2;, produces lactic acid.
3. Aerobic (oxidative): 3 min+, moderate intensity, uses O&sub2;, produces CO&sub2; and H&sub2;O.
2. Anaerobic lactic (glycolytic): 10 sec–3 min, high intensity, no O&sub2;, produces lactic acid.
3. Aerobic (oxidative): 3 min+, moderate intensity, uses O&sub2;, produces CO&sub2; and H&sub2;O.
Tap to reveal
Compare Type I and Type II muscle fibres.
Type I (slow-twitch): aerobic, fatigue-resistant, low power, high mitochondria. Used for endurance (marathon, cycling).
Type II (fast-twitch): anaerobic, fatigue quickly, high power, low mitochondria. Used for power and speed (sprinting, jumping).
Type II (fast-twitch): anaerobic, fatigue quickly, high power, low mitochondria. Used for power and speed (sprinting, jumping).
Tap to reveal
What is VO&sub2; max?
The maximum volume of oxygen the body can consume per minute during maximal exercise (mL/kg/min). The gold standard measure of aerobic fitness. Higher = greater aerobic capacity and endurance potential.
Tap to reveal
What are SMART goals?
Specific, Measurable, Achievable, Relevant, Time-bound. Must state exactly what is being improved, how it will be measured, and by when.
Tap to reveal
What is periodisation in training?
Systematic organisation of training into phases (macrocycle → mesocycle → microcycle) with varying intensity and volume. Ensures peak performance at competition time while preventing overtraining.
Tap to reveal
What are the FITT principles?
Frequency (how often), Intensity (how hard — % max HR), Time (duration), Type (what kind of training). Used to specify all variables of a training session.
Tap to reveal
Why does a taper reduce volume but maintain intensity?
Volume reduction allows fatigue to dissipate and glycogen stores to replenish. Maintained intensity preserves neuromuscular adaptations (fast-twitch fibre recruitment, enzyme activity). Dropping intensity would cause rapid detraining of power and speed.
Tap to reveal
Which energy system is used in a 400m race?
Both anaerobic lactic (dominant: high-intensity, 45–70 seconds, glucose oxidation without O&sub2;) and ATP-PC (explosive start) and aerobic (contributes to pace maintenance and recovery after the race). Training must develop all three but especially the lactic system and aerobic base.
Tap to reveal
What is lactate threshold?
The exercise intensity at which lactic acid begins to accumulate significantly in the blood. Athletes with a higher lactate threshold (as % of VO&sub2; max) can sustain higher intensities longer — a key performance determinant beyond VO&sub2; max alone.
Tap to reveal
What is overtraining syndrome?
A state of chronic fatigue, decreased performance, and increased injury/illness risk caused by insufficient recovery relative to training load. Prevented by periodisation: planned recovery periods (tapering, rest days, de-load weeks).
Tap to reveal
Why must training match the specific energy system of the sport?
Training adaptations are specific to the energy system stressed. Aerobic training develops mitochondrial density and aerobic enzymes; anaerobic training develops lactate tolerance and ATP-PC stores. Training the wrong system produces minimal sport-specific improvement.
Tap to reveal
Give one strength and one limitation of the bleep test.
Strength: simple, practical, can test large groups, provides a predicted VO&sub2; max score. Limitation: indirect (predicted, not measured) VO&sub2; max; heavily dependent on participant motivation; surface conditions affect results; running-specific (not valid for swimming fitness).
Tap to reveal
What is interval training?
Alternating periods of high-intensity exercise with recovery periods. Develops both anaerobic (lactic) and aerobic systems; increases lactate threshold; sport-specific when intervals match competitive demands. Common in swimming, running, cycling, and team sports.
Tap to reveal
Why are lactic acid and fatigue linked?
Lactic acid production during anaerobic glycolysis is accompanied by H+ ions (hydrogen ions) that lower muscle pH. This acidity inhibits enzyme function and muscle contraction — causing the burning sensation and fatigue. Lactic acid itself can actually be used as fuel; the H+ is the primary fatigue agent.
Tap to reveal
What is running economy?
The oxygen cost of running at a given speed. More economical runners use less oxygen per km, getting more "output" from their aerobic capacity. Two athletes with the same VO&sub2; max may perform very differently depending on running economy.
Tap to reveal
PHE · Practice Test
Practice Test — 20 Questions
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