Fatigue & the Recovery Process

Question 1

define lactate threshold

Answer 1

the point during exercise when the lactate produced exceeds the rate at which it can be cleared or used by the body

Question 2

why is the lactate threshold important? (2)

Answer 2

• it is an indicator of endurance performance
• the higher a person’s lactate threshold, the longer they can exercise at a high intensity before fatigue occurs

Question 3

how is the lactate threshold measured?

Answer 3

• typically in a laboratory setting using a graded exercise test
• 5 to 9 stages of exercise
• blood samples are taken after each stage to determine the point at which lactate begins to accumulate rapidly

Question 4

what is the lactate turn point also known as?

Answer 4

OBLA
onset of blood lactate accumulation

Question 5

what effect does training have on OBLA?

Answer 5

it pushes OBLA/the lactate turn point higher; even at a higher power output/exercise intensity, smaller amounts of lactate is present within the blood

Question 6

what are the benefits of training near the anaerobic/lactate threshold? (3)

Answer 6

the body is able to

• improve its use of lactate as an energy source (via the cori-cycle)
• improve its clearance mechanisms (removal of lactate and H+)
• improve the buffering capacity to negate the fatiguing effects of metabolic waste product accumulation

Question 7

what does buffering capacity mean?

Answer 7

the ability of the muscles to neutralise the acid that accumulates in them during high intensity exercise

Question 8

state what the cori-cycle is

Answer 8

the process where lactic acid is transported in the blood to the liver, where it is converted to blood glucose and glycogen

Question 9

why does ventilation increase exponentially during sustained, high intensity work? (4)

Answer 9

• during anaerobic glycolysis, lactic acid is produced by the pyruvate
• lactic acid dissociates into lactate and hydrogen ions, leading to an increase in acidity in the muscles and blood
• to buffer this acidity, the body uses the bicarbonate buffer system
• this reaction produces CO2 as a byproduct, which diffuses into the bloodstream to then be exhaled

Question 10

what are the immediate physiological effects of lactic acid within working muscles? (5)

Answer 10

• increased hydrogen ion concentration (pH decrease)
• muscle fatigue and discomfort
• impaired glycolysis and ATP production
• inhibition of enzyme activity
• oxygen debt

Question 11

describe the cori-cycle step by step (5)

Answer 11

• lactate is produced during moderate to high intensity exercise

in the liver
- 2X lactate becomes 2X pyruvate
- this 2X pyruvate then becomes glucose

in the muscle
- glucose becomes 2X pyruvate
- this 2X pyruvate then becomes 2X lactate before being transported back to the liver again