Lab 2 - Blood Lactate during Exercise

Question 1

What occurs to lactate at physiological pH?

Answer 1

H+ lactate dissociates into H+ and lactate (-) ions

Question 2

Lactate concentration at rest

Answer 2

0.5-2.0 mmol/L

Question 3

What causes lactate accumulation?

Answer 3

• at higher intensities, pyruvate production exceeds the maximum rate of pyruvate conversion into Acetyl-CoA
• therefore to prevent pyruvate accumulation (which would inhibit glycolytic pathway), pyruvate is converted into lactate and put into circulation

Question 4

What occurs when exercising above the lactate threshold but below the lactate turn point?

Answer 4

• lactate concentration increases to a certain point depending on how close the intensity is to the lactate turn point, and then reaches a steady state
• steady state occurs because the appearance and disappearance of lactate in the blood is equal/balanced
• lactate put into blood by working muscles, and is taken in from the blood and oxidized by other tissues

Question 5

What is MLSS?

Answer 5

• short for maximum lactate steady state
• maximum intensity at which lactate levels will eventually stabilize in the blood
• conceptually similar to CP/CS

Question 6

What occurs when exercising above MLSS?

Answer 6

• “LACTATE TURNPOINT”
• accumulation of lactate in blood, due to imbalance between uptake and input of lactate in bloodstream (way more lactate being put into bloodstream from working muscles than being taken out of bloodstream by other tissues)
• lactate concentration continually increases (lactate accumulation) until fatigue is reached