Explain the energy systems used during exercise with a neat diagram. Give sports examples.

How to lay out the answer. Follow the frame, then write it in your own words.

1 · Open in two lines. ATP is the only direct energy source for muscle, but only 2-3 seconds' worth is stored. Three systems rebuild it.
2 · Draw the energy continuum. [Flow: stored ATP → ATP-PC (10 s) → anaerobic glycolysis (10 s-2 min) → oxidative (beyond 2 min)]
3 · ATP-PC system.
- PCr + ADP → ATP + creatine (creatine kinase).
- No oxygen; fastest; tiny store.
- Sprints, throws, jumps, a fast bowler's delivery.
4 · Anaerobic glycolysis.
- Glucose or glycogen → pyruvate → lactate.
- Net 2 ATP per glucose; hydrogen ions build up.
- 400 m, a kabaddi raid, the finish of an 800 m.
5 · Oxidative system.
- Carbohydrate and fat → Krebs cycle → electron transport chain.
- About 30-32 ATP per glucose; slow but nearly unlimited.
- Marathon, road cycling, a full hockey match.
6 · Compare in a table. Oxygen, fuel, site, rate, capacity, yield, by-products and duration.
7 · Nutrition link. Creatine and protein for ATP-PC sports; full glycogen for glycolytic events; carbohydrate loading and fluids for endurance.
8 · Close in one line. The systems overlap; the sport's intensity and duration decide which one the diet must support.

Scoring tip: Draw the continuum first and label times on it. Give at least one Indian sport for each system.