Lactate Threshold

Question 1

What system forms lactate?

Answer 1

The short term glycolytic system

Question 2

Blood lactate does accumulates at all levels of physical activity…True or False

Answer 2

False

Blood lactate does not accumulate at all levels of physical activity

Question 3

When does blood lactate formation equals lactate

disappearance and oxygen-consuming reactions adequately meet energy demands

Answer 3

During light and moderate PA (<50% VO2max)

Question 4

In healthy, untrained people, when does blood lactate begin to accumulate
and rise in an exponential manner?

Answer 4

50-55% VO2max

Question 5

Why does blood lactate occur?

Answer 5

o Glycolytic metabolism predominates and NADH production exceeds the
cells capacity for shuttling its hydrogens down the respiratory chain due to insufficient oxygen supply or oxygen use at the tissue level

o The imbalance in hydrogen release and subsequent oxidation causes pyruvate to accept the excess hydrogens and become lactic acid

o This is converted to lactate in the body and begins to accumulate

Question 6

What needs to be resynthesised needs to
continue to meet the
energy demands of the
working muscle

Answer 6

ATP baby!!

Transferring hydrogen
ions from NADH to
pyruvate to form lactate
we then free up NAH+ to
be recycled through
glycolysis and continue to
resynthesize ATP

Question 7

The point at which lactate starts to increase from baseline is termed the ______ ______ and the point at which it begins to increase and accumulate is the ___________ _______

Answer 7

Lactate Threshold

Lactate Turnpoint

Question 8

What is the definition of Lactate Threshold?

Answer 8

The highest oxygen consumption or exercise
intensity achieved with less than a 1.0mm
increase in blood lactate concentration above the pre-exercise level

Question 9

Name 4 factors related to lactate threshold

Answer 9

• Low tissue oxygen
• Reliance on glycolysis
• Activation of fast-twitch muscle fibres
• Reduced lactate removal

Question 10

What is the definition of Lactate Turnpoint?

Answer 10

An increase in blood lactate of greater than
2mmol/L from the previous exercise
intensity

Question 11

What is Onset of Blood LactateAccumulation

(OBLA)?

Answer 11

When blood lactate concentration systematically increases to 4.0mM

Signifies initiation of an exponential accumulation of lactate in muscle tissue

Question 12

What are the Metabolic Factors influencing lactate production?

Answer 12

1. Inadequate rate of oxygen delivery due to:
   ◦ Lowered blood oxygen content;
   ◦ Lower blood flow to skeletal muscle
2. Imbalance between rates of glycolysis and mitochondrial respiration;
3. Increased NADH relative to NAD+;

4.Increased catecholamine’s:
◦ Higher intensities= increased adrenaline/nor adrenaline;
◦ Increased glycolysis

Question 13

Trained endurance athletes perform steady-rate aerobic exercise at intensities
between 80-90% of VO2max - why might they be able to do this?

Answer 13

• Athletes specific genetic endowment
• Specific local training adaptations that favour less lactate production

• More rapid removal of lactate via greater turnover and/or conversion at any intensity of
exercise

Question 14

What are the benefits of being endurance-trained?

Answer 14

1. Increased delivery of oxygen
2. Increased utilisation of oxygen
3. Increased oxidation of lactate

Question 15

Why are training adaptations beneficial?

Answer 15

• Enhance cellular capacity to generate ATP aerobically through glucose and fatty acid catabolism resulting in a lower requirement of anaerobic glycolysis at a given workload
• Conserves glycogen reserves, which inhibits the processes of muscular fatigue and
  extends the duration of intense aerobic effort

Question 16

Lactate Threshold is a functional index of ______ _________

Answer 16

Muscle fatigue

Question 17

What is termed as a success in endurance events

Answer 17

Sustain a high % of VO2max without accumulating fatigue is of greater
importance

Question 18

Why is identifying the Lactate Threshold is very important for endurance athletes?

Answer 18

1. Sets the highest work-rate that can be sustained without fatigue or rapid glycogen depletion
2. Is useful for setting an upper limit for ‘aerobic’ or ‘steady-state’ training

Question 19

What is the definition for Ventilatory Threshold?

Answer 19

The point where pulmonary ventilation

increases disproportionally relative to increases in oxygen consumption

Question 20

The excess ventilation comes from the release of CO2 as a result of the ____________________ (finish the scentence)

Answer 20

buffering of lactic acid that begins to accumulate in glycolysis

Question 21

What does the anaerobic threshold indicate?

Answer 21

Increased reliance on anaerobic processes

(Attempts to validate a linkage between ventilator changes and glycolytic events at the cellular level have however proved elusive)