C1 - Energy Systems

Question 1

What is the ATP-PC system?

Answer 1

Anaerobic energy system using phosphocreatine (PC) to rapidly resynthesize ATP.

Provides energy for high-intensity, short-duration activities (e.g., sprinting, weightlifting).

Question 2

What are the pros of the ATP-PC system?

Answer 2

✅ Immediate energy release (no delay for oxygen).
✅ No by-products (only ADP & Pi).
✅ Quick recovery (fully replenished in 3 minutes).

Question 3

What are the cons of the ATP-PC system?

Answer 3

❌ Limited PC stores (~8-10 sec of energy).
❌ Only supports maximal effort for a short time.
❌ Requires passive recovery for full replenishment.

Question 4

What is the anaerobic glycolytic system?

Answer 4

Breaks down glycogen into glucose without oxygen to produce ATP.

Used in medium-duration, high-intensity activities (e.g., 400m sprint, gymnastics routine).

Question 5

What are the pros of the anaerobic glycolytic system?

Answer 5

✅ Rapid ATP production.
✅ Lasts longer than ATP-PC system (~30-60 sec).
✅ Provides energy when oxygen is limited.

Question 6

What are the cons of the anaerobic glycolytic system?

Answer 6

❌ Produces lactic acid, leading to fatigue.
❌ Slower than ATP-PC system.
❌ Energy production limited to ~1 minute.

Question 7

What is the aerobic system?

Answer 7

Uses oxygen to break down glycogen, fats & proteins for long-term ATP production.

Used in endurance activities (e.g., marathon running, cycling).

Question 8

What are the pros of the aerobic system?

Answer 8

✅ Produces large amounts of ATP.
✅ Uses multiple fuel sources (carbs, fats, proteins).
✅ No harmful by-products (only CO₂ & H₂O).

Question 9

What are the cons of the aerobic system?

Answer 9

❌ Slow ATP production.
❌ Requires oxygen availability.
❌ Cannot sustain very high-intensity activity.

Question 10

What is the energy continuum?

Answer 10

Shows how different energy systems contribute to ATP resynthesis depending on intensity & duration.

Short bursts = ATP-PC system.
30 sec - 3 min = Anaerobic glycolytic system.
3 min+ = Aerobic system.

Question 11

What is an example of energy continuum in sport?

Answer 11

100m sprint – ATP-PC system.
400m race – Anaerobic glycolytic system.
Marathon – Aerobic system.
Football – Uses all three systems depending on sprinting, jogging, and rest periods.

Question 12

What happens to oxygen consumption during exercise?

Answer 12

Oxygen demand increases.
Oxygen uptake (VO₂) rises until a steady state is reached.
Some energy is still produced anaerobically at the start due to oxygen deficit.

Question 13

What causes fatigue?

Answer 13

PC depletion (ATP-PC system can’t function).
Lactic acid accumulation (reduces enzyme efficiency).
Glycogen depletion (aerobic energy production slows).
Dehydration & electrolyte loss (affects muscle contraction).

Question 14

What is oxygen deficit?

Answer 14

The shortfall between oxygen supply & demand at the start of exercise.

ATP is produced anaerobically in this phase.

Question 15

What is oxygen debt (EPOC)?

Answer 15

Excess Post-Exercise Oxygen Consumption (EPOC) is the extra oxygen consumed after exercise to restore the body.

Question 16

What happens during EPOC?

Answer 16

• Fast component: Resynthesizes ATP & PC stores, replenishes oxygen in myoglobin.
• Slow component: Removes lactic acid, restores glycogen, maintains elevated breathing/HR, controls body temperature.

Question 17

What are the stages of recovery in EPOC?

Answer 17

Fast Component (Alactacid Debt):
- Lasts ~3 mins.
- Restores ATP-PC stores.
- Reoxygenates myoglobin.

Slow Component (Lactacid Debt):
- Lasts ~1 hour+.
- Removes lactic acid via oxidation, conversion to glycogen or excretion.
- Maintains high HR & breathing rate to clear CO₂.
- Restores muscle glycogen & repairs tissue.

Question 18

What is lactate?

Answer 18

A by-product of anaerobic glycolysis.
Accumulates when oxygen supply is insufficient.
Contributes to fatigue but can also be used as fuel.

Question 19

How is lactate removed?

Answer 19

Converted back to pyruvate & oxidized.
Stored as glycogen in the liver.
Buffered by bicarbonate to maintain pH.

Question 20

What is EIMD & DOMS?

Answer 20

• EIMD: Microscopic muscle damage due to intense exercise.
• DOMS: Muscle soreness 24-48 hours after exercise.

Question 21

What are the causes of DOMS?

Answer 21

Eccentric contractions (lengthening under tension).
Micro-tears in muscle fibers.
Inflammatory response causing pain.

Question 22

How can DOMS be reduced?

Answer 22

Active recovery, massage, ice baths, stretching, proper warm-up & cool-down.

Question 23

What is priming for exercise?

Answer 23

A pre-exercise warm-up to prepare the body for performance.

Question 24

Why is priming important?

Answer 24

Increases oxygen uptake – reduces oxygen deficit.
Raises muscle temperature – improves enzyme function.
Activates neuromuscular pathways – enhances movement efficiency.
Reduces risk of injury.

Question 25

What is respiration?

Answer 25

The process of breaking down glucose & oxygen to produce ATP for energy. ## Footnote Can be aerobic (with oxygen) or anaerobic (without oxygen).

Question 26

What are the three stages of aerobic respiration?

Answer 26

1️⃣ Glycolysis (cytoplasm): Glucose → 2 Pyruvate + 2 ATP. 2️⃣ Krebs Cycle (mitochondria): Produces 2 ATP + CO₂. 3️⃣ Electron Transport Chain (ETC) (mitochondria): Produces 34 ATP + H₂O.

Question 27

What is the difference between anaerobic respiration and aerobic respiration?

Answer 27

- **Anaerobic**: Quick ATP, no oxygen, lactic acid buildup. - **Aerobic**: Slower ATP, oxygen present, large ATP yield (36-38 ATP).

Question 28

What is the role of mitochondria in respiration?

Answer 28

Site of the Krebs Cycle & ETC. ## Footnote More mitochondria = greater aerobic capacity.

Question 29

How are FFAs used in aerobic metabolism?

Answer 29

Lipolysis breaks down triglycerides into free fatty acids (FFAs). FFAs are transported in blood and converted into Acetyl-CoA. Enters the Krebs Cycle to produce ATP.

Question 30

When are FFAs used as fuel?

Answer 30

At rest & low-intensity exercise. When glycogen stores are low (e.g., endurance events).

Question 31

Why are FFAs not used at high intensity?

Answer 31

Require more oxygen to break down. Slower ATP production than carbohydrates.

Question 32

What are the pros & cons of using FFAs for energy?

Answer 32

✅ Large fuel source (stored as body fat). ✅ Efficient ATP yield. ❌ Requires lots of oxygen. ❌ Slow energy release (not useful for high-intensity bursts).

Question 33

What are the two phases of EPOC?

Answer 33

1️⃣ Fast Component (Alactacid Debt): Restores ATP-PC system & oxygen stores. 2️⃣ Slow Component (Lactacid Debt): Removes lactic acid, restores glycogen & body temperature.

Question 34

What happens in the fast component?

Answer 34

- Resynthesizes ATP & PC stores (50% in 30 sec, full in 3 mins). - Reoxygenates myoglobin (restores oxygen in muscles) - Restoration of phosphagen by conversion of ADP to ATP + PC - Resaturation of haemoglobin - Energy for ATP + PC re-synthesised - Start of oxidation of lactate by conversion to glycogen/glucose

Question 35

How long does the fast component last?

Answer 35

2-3 minutes after exercise.

Question 36

How much oxygen is used in the fast component?

Answer 36

3-4 liters of oxygen.

Question 37

What happens in the slow component?

Answer 37

- Oxidiation of lactic acid - Maintains elevated breathing & HR: Clears CO₂, supplies oxygen to muscles - Replenishes muscle + liver glycogen stores - Restores body temperature (excess heat dissipates) - **Gluconeogenic mechanim**: EPOC resynthesises lactate to oxygen

Question 38

How long does the slow component last?

Answer 38

Up to 24 hours, depending on exercise intensity.

Question 39

How much oxygen is used in the slow component?

Answer 39

5-8 liters of oxygen.