Exercise Metabolism

Question 1

Describe carbohydrate

Answer 1

1.energy source : glucose
2.stored form: glycogen
3.stored where: liver and muscle
4.breakdown process: glycogenolysis

Question 2

Describe fats

Answer 2

1.Energy source: fatty acids
2.stored form: triglycerides
3.stored where: muscle and adipose tissue
4.breakdown process: lipolysis

Question 3

How do we estimate utilisation of fuel during submaximal exercise

Answer 3

Measure meant of pulmonary gas exchange provides a noninvasive technique to estimate fuel utilization and involved measurement of respiratory exchange

Measurement assumes that no protein is used as fuel

Question 4

What causes the shift from fat to CHO metabolism as exercise intensity increases

Answer 4

1. Recruitment of fast muscle fibres, fewer lipolytic enzymes
2. Increasing blood levels of epinephrine stimulate glycolysis and lactate production. (Inhibits fat metabolism by reducing the availability of fat as a substrate)

Question 5

Glycogen is depleted during prolonged high intensity exercise:

Answer 5

1. Decreased rate of glycolysis and production of pyruvate
   2.decreased rate of Krebs cycle oxidation

Question 6

What exercise intensity is best for burning fat

Answer 6

20% vo2 max was better than 60% vo2 max

Question 7

Influence of exercise intensity on fuel source:

Answer 7

1. Relative contribution of muscle glycogen and blood glucose varies as a function of the exercise intensity

2.increased rate of glycogenolysis due to recruitment of fast twitch fibres and elevated blood epinephrine levels.

Question 8

Influence of exercise duration on fuel source:

Answer 8

Immediate energy sources in muscle depleted over time such as muscle glycogen and blood glucose.

Increased reliance on substrates in the blood such as plasma FFA and muscle triglycerides

Question 9

Describe lactate threshold

Answer 9

The point at which blood lactic acid rises systematically during exercise.

Question 10

When does lactate threshold occur

Answer 10

1. At 50-60% vo2 max in untrained subjects
   2.occurs at higher work rates (65-80% vo2 max) in endurance trained subjects.

Question 11

What is a possible explanation for lactate threshold

Answer 11

Accelrated glycolysis:
1. NADH produced faster than it is shuttled into mitochondria.
2.failure of this mechanism to keep up with the rate of glycolysis results in pyruvate accepted un shuttled hydrogen to form lactate

Question 12

What is another possible explanation for lactate threshold

Answer 12

Reduced rate of lactate removal from the blood:
Blood flow to muscle prioritized over tissues responsible for removing lactate

Question 13

Does lactate cause muscle soreness

Answer 13

No, lactate removal from blood is rapid. Sprinters would experience soreness every training session

Question 14

What is lactate shuttle

Answer 14

Lactate Produced in one tissue and transported to another to be used as an energy source.

The cycle of lactate/glucose between the muscle/liver is called the cori cycle