Exercise physiology diet & nutrition 2.1.6 Strategies for Optimal Intake Learning Objective: Learners should be aware of the strategies for ensuring optimal food, fuel and fluid intake for pre-, during and post-physical activity: carbohydrate (CHO) loading, two hour window of opportunity, protein intake, pre-, during and post-event hydration.

Pre-activity diet preparation Food should be eaten 1-4 hours before activity so that it is well digested and absorbed into the bloodstream. It should be high in carbohydrates, low in fat and moderate in fibre to assist the digestive process. Avoid saturated fats and even large amounts of protein as these take longer to digest and oxygen will be taken from muscles to assist in the digestion process. Make sure that you are well hydrated prior to exercise.

During-activity diet It is essential that athletes stay hydrated during exercise. Little and often prevents bloating. Taking on extra carbohydrates can boost energy levels but this is only really necessary for activity lasting over 90 mins (e.g. marathon running). Depleted glycogen stores can result in reduced performance and potential injury. Fats should be avoided as they take longer to break down.

Post-activity diet Post-workout nutrition can help you: •recover; •rehydrate; •refuel; •build muscle; and •improve future performance. Carbohydrates are essential at this stage to replenish your depleted energy stores while protein is important for growth and repair of muscle fibres. Fluids also play a key role as some dehydration is likely to have occurred.

The 2-hour window of opportunity Upon finishing your training session there is said to be a 2 hour period when your muscles are primed to accept nutrients that can stimulate muscle repair, muscle growth, and muscle strength. It is therefore essential that an athlete plans ahead so that they can eat quickly post-exercise. As many people don’t feel like eating straight after exercise a high protein / high sugar chocolate milkshake could be ideal!

Carbo-loading: why? When running a marathon the body will use both glycogen (stored form of carbohydrates) and fat for energy. Fat takes longer to break down. The feeling of ‘hitting the wall’ occurs when glycogen stores are fully depleted and the runner must reply only on fats for energy. The body’s glycogen stores can only last for around 90 mins and therefore carbo-loading can be useful for endurance athletes. Brownlee Brothers hitting the wall

Carbo-loading: how? There are a variety of different methods. Current thinking is that carbo-loading should start 2-3 days before the event. At this point 85-95% of calories should come from carbs. Your total calorie intake for each day can remain the same (greatly increasing calorie intake can cause bloating and stomach problems).

Explain how an athlete’s diet can aid the recovery process. (4) A linked explanation which makes reference to any the following points (up to a maximum of four marks). Glycogen replenishment is fastest during the first two hours of recovery (1). Water to replace fluid lost through sweating (1) and help restore body to homeostasis (1). Electrolyte replenishment to replace minerals lost in sweating (1). Protein to aid tissue damage and repair (1). A maximum of 1 mark for non-linked statements.