Diet, hydration and energy
Diet and energy
The body gets energy for physical activity from and .
- Carbohydrates are stored as in the muscles and liver. They are the main fuel, and the one used in high-intensity activity.
- Fats are used in long, activity, such as a long walk or a slow, steady swim.
So what a performer eats affects how much energy they have:
- Endurance performers, such as marathon runners, may eat more carbohydrate in the days before an event, so their glycogen stores are full and they can keep going for longer.
- In very long events, they may take in carbohydrate during the event, such as an energy drink, to keep up their energy.
- After training, carbohydrate replaces the glycogen used, and protein helps muscles recover and repair.
Key terms
Hydration and dehydration
During exercise the body loses water in , to cool down. If it isn't replaced, the performer becomes .
Effects of dehydration:
- the blood becomes thicker, so the heart has to work harder and
- the body overheats, because it can't sweat enough to cool down
- tiredness, headaches and muscle cramps
- slower reactions and poorer decisions.
All of these make performance worse. Performers stay hydrated by drinking water before, during and after exercise, especially in long events and hot weather.
Exam tip
Explain the effect on performance: 'dehydration causes muscle cramps, so a tennis player moves to the ball more slowly'.
Key terms
Examples from sport
| Performer | Diet and hydration | Why |
|---|---|---|
| Marathon runner | Plenty of carbohydrate before the race; water and energy drinks during it | Full glycogen stores, and energy and water topped up over a long event |
| Weightlifter or sprinter | Protein after training | Repairs muscle, helping it recover and grow stronger |
| Footballer | Carbohydrate before a match; drinks at half-time | Energy for 90 minutes; replacing water lost in sweat |
| Tennis player in hot weather | Drinks between games | Prevents dehydration, overheating and cramps |
Performers' needs differ because their activities use different amounts of energy, for different lengths of time.