Health and Nutrition
Nutrition for Sports Performance
How Much Food?
As well as this extra energy used up in exercise, the metabolic rate is speeded up for some time after exercise, provided that the exercise is sufficiently intense and prolonged. These extra calories used up after exercise are important to the person who uses exercise to reduce or control body weight, but are not easily earned. For this to be meaningful, the exercise should last about 60 minute and should be fairly intense. This is far beyond the level of exercise necessary to gain the optimum health benefits that accompany an active lifestyle. For the athlete in intense training, this increased energy expenditure is usually not wanted: it just means more food to be eaten.
The amount of food we eat should provide enough energy to match our energy expenditure: too much and body weight (especially body fat) increases: too little and body fat falls. This is fine up to a point, but exercise capacity is soon impaired. Obesity is reaching epidemic proportions, so it is clear thatfor many people there is an excess energy intake. Many factors are responsible for this and there is no easy answer, even though the solutions are obvious. Either energy intake must be reduced or energy expenditure must be increased. In practice, some combination of these options usually works best. In the short term it is easy to achieve a large reduction in energy intake, but it is almost impossible to sustain this for long periods of time. Equally, it is difficult for people accustomed to a sedentary life to achieve large increases in exercise levels over a short time scale.
Exercise and Energy Needs
During exercise, metabolic rate is increased to meet the energy demand of the working muscles, so an increased level of physical activity might be expected to lead to either:
- negative energy balance and a falling body weight
- increased energy intake to balance the increased expenditure
Effects of Exercise on Energy Balance
Increasing energy expenditure
Energy cost of exercise
Elevation of post-exercise metabolic rate
Potentiation of thermogenic effect of food
Decreasing energy expenditure
Decreased activity levels
Increasing energy intake
Stimulation of appetite
Decreasing energy intake
Suppression of appetite
Disturbances of meal patterns
| All of these factors make it difficult to estimate or predict an individual's energy requirement. |
