Diet and Nutrition Flashcards
What are nutrients used for in the body?
- support
- energy
- growth and repair of body tissue
Macronutrients and example
Needed in large amounts as they provide energy for body and build body structure
- carbs, fats and proteins
Micronutreints and example
- Needed in small amounts and contain no energy themselves but help sustain body functions
- vitamins, minerals and roughage
Carbs
Main source of energy
55% of diet
Fats
One source of energy and important in insulation
30% of diet
Proteins
- broken down into amino acids enter bloodstream for growth and repair of muscle and other body tissue
15% of diet
Roughage
fibrous ,indigestible portion of our diet essential to health of digestive system
Positive energy balance
Individual consumes more calories than they burn, resulting in weight gain
Negative energy balance
Individual burns more calories then they consume, resulting in weight loss
How much oxygen is needed to breakdown carb and fat molecules?
takes 15% less O2 to breakdown carbs
Fuelling the energy system at low intensity
(below 50% of max HR)
enough stored fat for hours / days, as long as there is sufficient o2 to allow fat metabolism to occur
(75-25) fats
Fuelling the energy system at increased intensity
- Metabolism of glycogen stores takes over
- Stored glycogen can fuel about 2 hours of moderate to high intensity
- After glycogen depletion occurs fuel isn’t replaced as athlete may ‘hit a wall’
- If insufficient carbs consumed performer forced to reduce intensity and return to fat metabolism to fuel activity
(50%-50%)
Intensity increases even further
- aerobic system using carbs cannot provide sufficient ATP and anaerobic metabolism takes over
- Body doesn’t take in oxygen and distribute oxygen quickly enough to cope with the exercive energy demands of high intensity
(25-75) carbs
What does increasing aerobic fitness help with when fuelling energy systems ?
Increasing their VO2 max allows them to metabolise fats for a longer period than that of someone who is less anaerobically fit
- Allows glycogen levels to be maintained, which is beneficial when exercise intensity is increased and carbs/glycogen will be the main fuel.
What does increasing anaerobic fitness help with when fuelling energy systems ?
- have increased glycogen and creatine phosphate stores, thus allowing longer periods of high intensity exercise
The Glycaemic Index
The rate at which carbohydrate releases energy (glucose) into the blood stream
- high, medium, low
High GI carbohydrates
Release energy/ glucose quickly, if not used it is stored as fat
(during game e.g fruit, jelly )
- result in them being stored as fat if they are used by the body for energy.
If someone has a continued consumption of high GI food, what can occur?
- diabetes
- pancreas secretes insulin to control blood sugar levels over time body can become tolerant to it.
Low GI Carbs
Release energy at a far slower, more gradual rate
- Leaves individuals less hungry over time
(before game e.g porridge)
What is carbohydrate loading?
- Muscle glycogen levels normally 100-120 mmol/kg
- Carbo loading enables levels to be increased to 150-200 mmol/kg
Improving performance by 2-3%
What does the Sherman Method follow ?
Depletion Stage - Reduce muscle glycogen stores
Tapering Stage - reducing amount of training
Loading stage - increasing the consumption of carbs
Quick carbo loading method
Deplete glycogen stores on the day prior to competition with short burst of exercise
- Loading phase begins immediately after exercise with 80% carb diet
How does carbohydrate loading improve performance ?
- Increase amount of glycogen stored in muscle
- perform at higher intensity for longer
- Break down glycogen for longer and prevent ‘hitting the wall’ not using fat as fuel
Hydration
maintaining the correct levels of water in the body to allow normal bodily functions
Physiological responses to Dehydration
- Increase heart rate and breathing
- Increase levels of lactic acid production
- Less glucose and fatty acids being transported to muscles for energy
- Oxygen being transported at a slower rate through blood vessels
What do all physiological symptoms cause ?
- reduction in amount of ATP produced, resulting in reduction of intensity
Signs of dehydration
- dry mouth
- Thirst
- Urine Colour
Effective hydration prior to exercise
- 4 to 7 litres of water over 24 hr period
- 2 litres over 2-3 hours prior to exercise, not all at once
Effective hydration during exercise
- Small amounts at regular intervals
- Consume 150-200 ml every 10-15 mins
- Exercise longer than 90 mins consumption of energy drinks may be beneficial to replace lost electrolytes and glycogen
Effective hydration after exercise
- Rehydrate to aid recovery
- Weigh before and after exercise. Every 1kg lost, 1 litre of water consumed
What happens when we lose electrolytes?
- Dehydrate quicker
- Struggle to regulate body temp
- Loss of sodium and water leads to muscle cramping
Hypotonic drink
- before exercise
- 1 to 3% carb content
- Quickly replace fluids, low in carbs
Isotonic drink
- During exercise
- 6 to 8% carb content
- Quickly replace fluid lost and boost of carbs
Hypertonic
- After
- 10+
- Supplement carb intake
top up muscle glycogen stores
Saturated fat
- increase LDLs
e.g lard, butter, cheese
Unsaturated fats
- Vegetable oils
- healthier
- HDLs
Commercially produced fats (trans fats)
- Unsaturated fats that have had hydrogen atoms added to them, making bonds more difficult to break down
- Artificial process to preserve shelf life
- These are essential fatty acids- no nutritional value
What does the consumption of trans fats increase?
- Risk of coronary heart disease by raising LDL level
