nutrition - lesson 9

Question 1

what are high GI carbohydrates?

Answer 1

• break down quicker during digestion
• have an immediate effect on blood glucose levels
• best consumed during an event + immediately after

Question 2

why should you consume high GI foods during an event?

Answer 2

• rapid absorption and release of energy
• top up glycogen stores
• helps glycogen sparing

Question 3

why should you consume high GI foods immediately after an event?

Answer 3

• first 30 minutes
• muscles responsive to topping up glycogen stores
• tops up muscle

Question 4

what is rebound hypoglycemia?

Answer 4

• when athletes consume high GI foods 30-60 min prior to the event
• rapid rise in blood sugar levels
• cause overshoot in insulin release
• significantly reduces blood sugar levels which impairs CNS function during exercise
• negative effect on performance

Question 5

what are low GI carbohydrates?

Answer 5

• break down slowly during digestion
• release glucose gradually into the bloodstream
• best-consumed pre-game and after

Question 6

why should you consume low GI foods before an event?

Answer 6

• 1-4 hours prior
• slower release = glucose levels topped up
• a benefit for endurance athletes
• allow athletes to burn “free fatty acids” early in the performance

Question 7

why should you consume low GI foods before an event?

Answer 7

• assists with replenishment of muscles and liver glycogen stores in the 1-24hrs past exercise

Question 8

The fuel source used for ATP production is based on?

Answer 8

• duration and intensity of exercise

Question 9

what fuel sources are used during rest (aerobic)?

Answer 9

• fat & glucose used

Question 10

what fuel sources are used during exercise?

Answer 10

• short duration /high intensity = anaerobic systems use carbs (lactic acid system) & chemical (ATP-PC)
• long duration/ low intensity = aerobic system uses carbs + fats = only fats are used once glycogen stores are depleted

Question 11

how are fuel sources used during exercise?

Answer 11

1. low-intensity exercise - stored fats are the main energy source
2. intensity increases = muscle glycogen contributes more - up to 90 mins = athletes hit the wall when muscle glycogen runs out = stored liver kicks in > depletion of liver glycogen
3. fats now become the primary fuel source & intensity of exercise is reduced as fats are more difficult to break down
4. depletion of fats results in protein being used as an energy source (only in ultra-endurance events)

Question 12

what is glycogen sparing?

Answer 12

= use of fats as a source of energy during exercise so that depletion of muscle glycogen stores is delayed

• body uses fats + carbs during endurance events
• glycogen stores depleted = muscle utilizes fat
• adaption = athletes can utilise fats even at a high intensity of exercise