4.3. Glycolytic System

Question 1

Describe the process of resynthesising ATP via the glycolytic system

Answer 1

• The lactic acid system breaks down glucose/ glycogen to provide energy via coupled reactions -> anaerobic glycolysis
• Glucose is provided directly from digested carbs/ stored glycogen located in the liver and muscles
• The decrease of PC stores activates the enzyme GPP to break down glycogen into glucose
• Glucose is then broken down into pyruvic acid by the enzyme PFK
• In the absence of o2, pyruvic acid is then converted into lactic acid through LDH

Question 2

What is the main limitation of the glycolytic system?

Answer 2

Due to the Onset Blood Lactate Accumulation (OBLA)

This accumulation of lactic acid decreases blood pH and therefore inhibits enzymes used in glycolysis. This causes fatigue and can be quite painful. OBLA occurs at 4mmol per litre of blood

Question 3

What is the site of reaction?

Answer 3

muscle sarcoplasm

Question 4

What is the type of reaction?

Answer 4

anaerobic

Question 5

What is the chemical fuel?

Answer 5

Glycogen/ glucose

Question 6

What are the controlling enzymes?

Answer 6

GPP
PFK
LDH

Question 7

What is the recovery process?

Answer 7

somewhere in the middle of alactacid and lactacid recovery

Question 8

What are the by products?

Answer 8

lactic acid

Question 9

What is the duration?

Answer 9

10-180 seconds

Question 10

What is the intensity?

Answer 10

high- varies with the performer

Question 11

What is the energy yield?

Answer 11

2 ATP
1:2

Question 12

Example of a performance that uses the glycolytic system

Answer 12

400m runner

Question 13

Adaptations to training

Answer 13

• Anaerobic training overloads system = increase in body’s tolerance to lactic acid
• Increases glycogen stores
• Delays OBLA, prolonging lactic acid threshold

Question 14

Advantages of the glycolytic system

Answer 14

• Compared to the ATP/PC system, there is double the yield of ATP
• Large glycogen stores in muscle/ liver = readily available as a potential energy source
• Fewer reactions than aerobic systems = quicker supply of oxygen
• Enzymes are activated as soon as PC levels decrease
• Provides energy for high intensity activities for 10-180 seconds

Question 15

Disadvantages of the glycolytic system

Answer 15

• Not as quick as ATP/PC system
• Produces lactic acid = fatiguing product = lowers pH = OBLA and enzyme inhibition = stimulation of pain receptors
• net effect = muscle fatigue/ tiredness and pain