MODULE 7 - FATS AS A SOURCE OF ENERGY DURING EXERCISE

a) REQUIREMENT

REQUIREMENT OF FAT

When the calorie requirement for an athlete is high, fat is necessary to make up for the deficit as it is a more concentrated form of energy.

If an athlete tries to restrict fat completely, he may not be able to consume enough food to provide the desired amount of energy for the activity.

1 g fat gives 9KCal

Fat as an energy substrate

Activity

Fat: Low Power Fuel

• Slow ATP production -- Fat can only produce ATP via aerobic metabolism

• Primary use by slow twitch muscle fibers (recruited during low-moderate intensity exercise)

b) REGULATION OF FAT METABOLISM

Energy Release from Fat

Adipocytes - Adipose tissue serves as an active and major supplier of fatty acid molecules.

Hormonal Effects

Break down of glycerol and fatty acids

Lipogenesis

ChylomicronMicelleApoproteinPhospholipid

c) FACTORS AFFECTING USE OF FAT DURING EXERCISE

FACTORS AFFECTING USE OF FAT DURING EXERCISE

1. Exercise intensity

2. Exercise duration

3. Training experience

• Prolonged continuous, moderate to intense activity that places high demands on aerobic metabolism.

• Physical activity performed at 70% VO2max over long duration involves a significant amount of fat oxidation.

• Endurance training promotes the use of intramuscular triglycerides as fuel substrates for exercise

• Increased fat oxidation as a result of endurance training is associated with decreased muscle glycogen use and improved endurance performance.

Note the following changes in substrate contribution to the total energy supply as energy intensity increases from 25% to 65% to 85% of VO2max:

• Muscle glycogen use increases.

• Muscle triglyceride use increases at 65% and then lessons at 85% VO2max.

• Plasma fatty acids use decreases.

• Total fat oxidation is the highest at 65% VO2max.

• Plasma glucose use increases.

• Total carbohydrate use is highest at 85% VO2max.

What does 100g of fat look like in food?

ACTIVITY:

Fueling Tips for Athletes: Before exercise training or competition

• Choose high-carbohydrate, low-fat foods you like.

• Eat foods and drink fluids that are familiar and comfortable.

• Choose foods you digest easily.

• Carbohydrate digests most quickly.

• Protein digests more slowly.

• Fat (especially fried foods) digests most slowly.

• Highly concentrated foods (energy gels, energy bars) slow digestion.

• Fiber in foods slows movement of food out of the stomach.

• Larger volumes (gulps) of fluid exit the stomach faster than smaller volumes (sips).

• Eat a meal or snack every 2-3 hours on training days.

• Eat meals about three hours before exercise.

• Eat less food if eating within two hours of exercise.

• Fuel with liquids or a small snack an hour (or less) before exercise.

• Anxiety, stress, and high intensity exercise slow digestion.

• Try new foods in training situations, not competitions

A short recap, first