Chapter 12: Sports Nutrition

Question 1

• Why does increased exercise mean greater food intake?
• What food fuel would be used at a max effort for short duration, sub-max for up to 2 hours and sub-max for 2+ hours?
• Describe the ATP-CP system
• Describe the anaerobic glycolytic (lactic acid) system.
• When is the aerobic glycolytic system used?
• Explain how the body can ‘hit the wall’ during a distance run.

Answer 1

• To meet the increased demands of wear and tear and the replenishment of glycogen stores.
• Carbohydrate, carbohydrate/fat and fat
• This system provides immediate energy supply for high intensity activity by breaking down stored ATP in muscles into ADP+P releasing energy. However CP stores in muscles are able to quickly break down into C+P to release energy to resynthesise ADP+P back into ATP. CP supplies are limited for about 10s and is replenished after 2mins rest.
• 2nd energy system lasting 10s-2mins. Carbs are the fuel for manufacturing ATP in this case. With enzymes, glycogen is converted to lactic acid while releasing energy to recombine ADP+P to ATP. However lactic acid is toxic in large amounts causing muscle fatigue.
• When sufficient O2 is pumped to muscles allowing ATP to be produced aerobically. ATP can be produced by the breakdown of carbs, fats or protein.
• The body’s preferred energy source are carbs stored as glucose in blood and glycogen in liver but during a distance run these could run out. At this point the body uses fat but is less efficient at converting it to energy, so fatigue sets in and problems with muscle contraction can start aka hitting the wall.

Question 2

• How will a high carb diet increase an athlete’s training frequency and load?
• Why is protein in a diet important?
• Why is carbohydrates in a diet important?
• Why is fats in a diet important?

Answer 2

• Increases rate of refuelling muscle and liver glycogen stores, increasing length of exercise before exhaustion and quicker recovery of muscle glycogen stores. Therefore increase training frequency and load.
• Can be broken down into amino acids which is the structural unit of cells and is required for the growth and repair of tissue. Found in foods of animal origin.
• They’re the 1st source of energy for the body. They can be simple carbs (sweets) and complex carbs (pasta).
• They’re the 2nd source of energy which are broken down into fatty acids and triglycerides. They can be stored in the body if not utilised for added protection and insulation for the body.

Question 3

• Why are minerals in a diet important?
• Why is water in a diet important?
• Nutrition Australia devised the healthy food pyramid to give guidelines on the amounts of each food types that should be consumed. What are the 3 guidelines?
• Describe glycaemic (GI) index?
• Describe how GI of a food is calculated.
• Describe glycemic load (GL)

Answer 3

• Essential for efficient nerve and muscle function. Obtained by fruit and vegetables.
• Makes 60% of the body, used for energy production, temp control, elimination of waste products and lubrication of joints.
• Maintain a weight by adjusting food intake and exercising, eat less fat, especially saturated fat and increase carbohydrate intake.
• Ranks carbs to their effect on blood glucose level. Low GI produces small rises in blood glucose and insulin levels and vice verser.
• Calculate amount to be eaten to provide 50g of carbs. Calculate it’s effect on blood glucose giving it a percentage score of 100.
• A ranking estimating how much the food will raise a person’s blood glucose level. It’s calculated by: Grams of carbs in food x food’s GI then divide by 100. GL takes into account the size of the portion and the fact that foods aren’t eaten in isolation.

Question 4

• How are GI levels differentiated into high, medium and low?
• How are GL levels differentiated into high, medium and low?
• What’s the effect of processed food on blood glucose?
• What types of food would you eat during exercise?
• what key factors should be considered for a pre-comp diet?
• What is the most important food source to eat after exercise?
• DISCUSS the nutritional considerations that triathletes should consider pre-, during and post-competition.

Answer 4

-High GI=70+, medium GI= 56-69 and low GI=55 and less.
-High GL=20+, medium GL=11-19 and low GL=10 and less
-processing foods, breaks up starch molecules, making digestion faster and blood glucose levels rise faster.
-High GI foods. They are digested and absorbed faster Eg sport drink.
-Eaten 3+ hrs before, increased carbs, reduced proteins, fibre and fat.
-Protein as it provides amino acids to rebuild tissue and increase water absorption from the intestines for hydration.
-PRE: low GI solid meal as low GI are digested and absorbed slower, resulting in a gradual release of glucose into the blood throughout the duration of the race. Also carbohydrate loading should occur days in advance to maximise glycogen stores in body.
DURING: high GI foods as they are digested and absorbed quickly; resulting in a rapid release of glucose into the blood to replenish used glycogen stores.
POST: high GI foods directly after as they are absorbed and digested faster; resulting in a rapid release of glucose into blood to replenish used glycogen stores. Also protein to enhance muscle recovery.

Question 5

• What are the results from excessive sweating?
• What are 3 tips to avoid dehydration?
• What is so good about sports drinks?
• Fats should not exceed __% of ones diet energy content, with __% of this being unsaturated fat.

Answer 5

• High loss in electrolytes, salt and water can affect skill production, co-ordination and endurance. Sweating also causes blood flow to be redirected to the skin from muscles and decrease blood volume so heart rate and cardiac output increases.
• Lots of water before, avoid alcohol, caffeine and sugar and 200ml of water every 15 mins.
• They contain carbs, Na and K.
• 30%. 70%

Question 6

• When should you eat low/medium GI foods and high GI foods?
• What is carbohydrate loading?
• What is the carbohydrate window?
• By understanding the goal keeper and midfielder requirements during the game, justify the difference in glycogen depletion you would expect for each player following the game.
• Describe three potential physiological changes that may occur as a result of appropriate ingestion of protein powder.
• Many energy drinks contain a legal stimulant. Identify the stimulant and describe 3 physiological changes that occur with ingestion of this stimulant that would explain why the shooter of a pistol shooter has advised the athlete to avoid consuming these drinks prior to training or competition.

Answer 6

• Low/medium GI foods pre exercise and high GI foods post exercise for recovery.
• The adjustment of training and nutrition to maximise carb stores.
• The 2 hour period after exercise where carbohydrate is converted to glycogen quicker than normal.
• Goal keeper uses more ATP-CP system for short bursts and gave long rests so would have less glycogen depletion. Whereas the midfielder performs many repeated sprints using the anaerobic and aerobic system throughout the game so would have more glycogen depletion.
• Muscle hypertrophy, decrease muscle breakdown and improve recovery.
• Increases heart rate, CNS activity and shaking of the muscles.