Lipids: Nutrition and Endurance Exercise

Question 1

Recommendations for pre-competition nutrient of carbs ..

Answer 1

1. athletes food preference
2. digestibility of food
3. contains 150-300g of CHO in solid or liquid form
4. consumed 1-4 hours before exercise for complete digestion and absorption to optimize glycogen stores

Question 2

What types of carbs are recommended for pre competition?

Answer 2

High glycemic index CHO digest and absorb more rapidly compared to protein
–> helps cause a rapid spike in glucose levels and are absorbed quickly
–> also causes a spike in insulin levels which causes the CHO to be brought up into the skeletal muscle and stored as glycogen

Question 3

Carbs serves as optimal nutrition to eat before endurance exercise for short term anaerobic and intense aerobic exercise

Question 4

How does protein facilitate dehydration?

Answer 4

Think about amino acids being broken down, this causes urinary excretion of urea and causes more urine production = dehydration

Question 5

What stays in the digestive tract longer, fat and fiber, or protein?

Answer 5

Fat and Fiber because you want to have gastric emptying before a sporting event to minimize gastrointestinal stress during competitions

Question 6

What is exercise induced hypoglycemia?

Answer 6

Low blood glucose
–> consumption of carb rich meal with a high glycemic index and/or glycemic response prior to exercise

results in:
- insulin secretion
- insulin and skeletal muscle contraction induced GLUT-4 exocytosis

Question 7

Two ways that GLU-4 can go through exocytosis.

Answer 7

1. Insulin
2. Skeletal muscle contraction

Question 8

Steps for Insulin to move GLUT-4 cells …

Answer 8

1. spike in blood glucose
2. insulin is releases from the pancreas
3. insulin binds to a receptor on cell membranes
4. when binds it causes a signal transduction cascade intracellular signaling
5. Signaling cause the GLUT-4 protein to exocytosis (move from deeper to cell membrane more outer)
   –> Transport protein that always glucose to enter the cell to be used or stored when talking about liver or skeletal muscle
6. Adipose tissue, glucose is converted into fatty acids and then the fatty acid will be stored as a triglyceride
7. All are bringing blood glucose levels back to normal

Question 9

Steps for skeletal muscle contraction to more GLUT-4

Answer 9

1. GLUT-4 will stay at the membrane for 4-6 hours while exercise
2. GLUT-4 proteins can be active by muscle contractions during exercise
   –> Then GLUT-4 proteins inside the skeletal muscle that goes to cell membrane which are activated by muscle contractions
   –> When you contraction muscle cell then there are signaling that is insulin independent
   –> Signals go to GLUT-4 proteins and then it can move to the cell membrane
   ——-> In the fasting state you can still get glucose to skeletal muscle because of the signals

Question 10

Having both systems, insulin and skeletal muscle contraction can cause what negative affects?

Answer 10

Can actually cause too much glucose in the system = Exercise Induced Hypoglycemia

Question 11

During the first 5 minutes of endurance exercise, energy/ATP is required immediately with the onset of exercise and must rely on what 4 immediate available energy sources?

Answer 11

1. ATP
2. Phosphocreatine
3. Skeletal Muscle Glycogen stores
4. Intra-Muscular Triglycerides (IMTGs)

Question 12

How much of ATP in grams is needed to help when we fist start working out but doesn’t last for too long (10-30 seconds) and so we have to use other sources to get the energy we need?

Answer 12

80-100 grams

Question 13

Skeletal muscle Glycogen stores are used when?

Answer 13

After the initial ATP stores are used up so that we can continue to contract our muscles
–> Use it in the process of anaerobic metabolism w/o oxygen

Question 14

What does anerobic metabolism do until steady state is achieved during endurance exercise ?

Answer 14

Provides energy

Question 15

How long can athletes rely on aerobic metabolism for ATP production?

Answer 15

For only the first mins. of endurance exercise
–> Oxygen uptake also increases immediately but it takes 1-5 minutes to achieve steady state

Question 16

Oxygen uptake also increases immediately but it takes 1-5 minutes to achieve steady state also causes …

Answer 16

1. Increase in ventilation when exercising and then oxygen has to go to respiratory system –> blood stream –> skeletal muscle –> to activate/increase enzymes that help oxygen move into/through skeletal muscle –> delivered to mitochondria where aerobic metabolism occurs
2. The more trained/athletic a person is the faster it takes them to achieve steady state in 1-2 minutes

Question 17

Hormonal and neural activation can cause an increase in circulating substrate in the first 5 minutes.

Answer 17

1.Increased epinephrine and norepinephrine –> released from sympathetic nervous system that drive responses and regulates the amount the circulates as soon as we start exercising
–> It tells pancreas to slow down and decrease the amount of insulin in the blood
–> Then glycogen increases being released from the pancreas
i. Function sin the liver
ii. it facilitates liver glycogen
breakdown into glucose and
into the blood
iii. Gluconeogenesis
2. minimal clearance of substates in the first 5 minutes

Question 18

What are the 5 factors that influence substrate utilization during endurance exercise?

Answer 18

1. exercise intensity –> DRIVING FACTOR
2. exercise duration
3. physical training
4. antecedent diet
5. hormones

Question 19

Exercise intensity relies on what during specific exercise intensities?

Answer 19

1. fat (fatty acids) or CHO (glucose)
2. at lower intensity exercise it relies on fat
3. at higher intensity exercise, relies more on CHO 926-27 min.)

Question 20

At higher intensity exercise which relies more on CHO what is the Crossover Concept?

Answer 20

A theoretical means to understand the effects of exercise intensity on the balance of carbohydrate and lipid metabolism during sustained exercise

–>In healthy people around 65% of VO2Max aerobic power, go from fat (major contributor) –> CHO as primary energy source

Question 21

Exercise duration is also another driving factor.

Question 22

As we go with exercise we start to deplete sores of liver glycogen and triglycerides in the body
–> we have limitless supply of triglycerides in the adipose tissue
–> liver glycogen stores (32 min.)

Question 23

What are the 2 driving factors that influence substrate utilization during endurance exercise?

Answer 23

1. exercise intensity
2. exercise duration

Question 24

How is blood glucose maintained even when glycogen stores are low/depleted?

Answer 24

1. Reduction in insulin which is told to decrease in production and the increase in epinephrine levels
2. Decreases protein anabolism and increased protein catabolism or breakdown

Question 25

Reduction in insulin which is told to decrease in production and the increase in epinephrine levels which causes ..

Answer 25

1. Decrease in glucose uptake by other tissues
2. increases lipolysis
3. increase glucagon secretion –> beneficial in gluconeogenesis

Question 26

Decreases protein anabolism and increased protein catabolism or breakdown …

Answer 26

1. This helps and gives framework for gluconeogenesis to increase from amino acids
   –> When glycogen is depleted gluconeogenesis from carbon skeletons of amino acids sustains the livers glucose output
2. When you have high CHO there is not a lot of protein breakdown
   –> Measured by the amount of urea in urine and sweat
   —–In rested state not as much urea
   —–Low CHO –> increased urea
   —–REMEBERE proteins break down increases the amino acid amount
3. Glucose Alanine Cycle: accounts for 45% of the liver’s total glucose release after 4 hours of continuous light exercise

–> 1: Glucose resynthesis
Steps:
i. Glucose goes into s. muscle to
be utilized and broken down by
anaerobic or aerobic
metabolism as energy source
- Anaerobic: end product by
glucose is pyruvate (Carbons,
Hydrogens, and Oxygens)
ii. Amino acid –> leucine .. high
amounts in the skeletal muscle
1.Can’t leave muscle easily
2. So, it trans animates itself
and transfers its amine
group (NH2) from itself to
another molecule in
cytoplasm of skeletal muscle
to form a new amnio acid
alanine and happens in
cytoplasm of skeletal muscle
iii. Alanine can leave easily
and go to liver
iv. Once in liver it deaminates
itself
1.Removes the NH2
amine group and
excreted as urea and
leave us with just
pyruvate
v. It then can be converted to
glucose
vi. Glucose can go back into circulation to muscle

Question 27

What is “hitting the wall”?

Answer 27

When individual experiences glycogen depletion from endurance exercise

–> Remember CHO is the main energy source for heavy intensive exercise

Question 28

What is “glycogen depletion”?

Answer 28

Decreases availability of blood glucose for optimal central nervous system function because the CNS really wants to use glucose as an energy source

–> Coincides with feelings of fatigue, sweating, hunger, fainting, shakiness, vomiting, confusion, dryness in mouth and tingling in lips, blurry visions, pins and needs, slurred speech, discoloration of skin

–> Aka hypoglycemia less than 70 grams per deciliter = A lot of athletes can mask the symptoms because they have been doing it for so long

Question 29

What are some benefits of CHO loading to enhance endurance performance?

Answer 29

1. Increase time to exhaustion
2. Reduces time to complete a task
3. May improve performance in team sports that involve fine and gross motor skills (whole body movements, .. running, jumping, hitting a ball

Question 30

What are some cons of CHO loading to enhance endurance performance?

Answer 30

1. Only good for a one day event
2. Increase water storage (1 g CHO stored with 3 g water

Question 31

What are some techniques that will help enhance endurance performance?

Answer 31

1. Depletion/repletion: exhaustive bout .. almost hitting the wall …7-10 days before competition –> few days 3-6 days slow CHO diet –> exhaustive exercise bout –> high CHO diet
2. Modified approach: taper training week before even while increase % CHO in diet
   –> Increase glycogen stores 20% more
3. Carbohydrate Intake During Exercise
   –> 30-60 grams/hour recommended (one liter of Gatorade

Question 32

More about Carbohydrate Intake During Exercise ..

Answer 32

1. LT1 .. sodium glucose transporters job ois to transport glucose to S.I so can be abosred into blood and are fully saturated a 60 glucose an hour … can’t absorb no more that 60 per hour
   –> Glucose goes through sodium glucose transporter
2. Improves exercise trial time and maintain exercise for longer at a given intensity
   –> Exogenous CHO maintains blood glucose
   –> Liver and skeletal muscle glycogen sparing
3. Ingestion of multiple transportable carbohydrates may further enhance endurance performance
   –> Fructose through GLUT-5 transporter
   - Co-ingest: Together glucose
   and fructose 1.2 to 8% more
   than glucose alone
   • Glucose alone is better than
     just water to enhance
     performance

Question 33

What is the primary goal to recovering from glycogen depleting exercise?

Answer 33

Glycogen synthesis and stimulate an anabolic environment

Question 34

To recover from glycogen depleting exercise, what is the critical window for maximal glycogen synthesis?

Answer 34

30 minutes
–> When you contract skeletal muscle, GLUT4 proteins move to skeletal muscle and allows glucose to move to cell membrane into skeletal muscle without insulin
- The second you stop exercising,
the GLUT4 don’t go back into
deep skeletal muscle cell
– They can stay at cell
membrane form another
4-6 hours after exercise
– But max amount of GLUT4
proteins is up to 30
minutes –> critical window
=
gets max glucose stores
and synthesis

–> Even under the best circumstances is takes at least 20 hours to reestablish glycogen stores following glycogen depleting exercise
- Type: moderate to high glycemic
index foods and causes
spoke of GLUT-4 from
insulin
- Amount: 1.2 per kg body weight
per hour or 7-10 g per kg body
wight total
- Combination with proeitn (2:1
ratio)
–> 1 g per kg body weight CHO
to 0.5 g per kg body wight
protein
–> Exercise alone causes muscle protein break down 32 min