Energy Transfer During Short Duration / High Intensity Exercise

Question 1

Lactate accumulation

Answer 1

• the higher the intensity of EX the more L.A is produced
• L.A is broken down, releasing H+ ions - the remaining compound then combines with Na+ ions or K+ ions to form salt lactate.
• as lactate accumulates in the muscles, more H+ ions are present which increases the acidity.
• this slows down enzyme activity which effects the breakdown of glycogen causing muscle fatigue.
• the lactate produced in the muscles diffuses into the blood and blood lactate can be measured.

Question 2

The lactate threshold and OBLA link

Answer 2

Crossing of the aerobic / anarobic threshold = lactate threshold - lactic acid rapidly accumulates in the blood

As the intensity of the Ex. Increases the body is unable to produce enough o2 to break down the lactate
- Levels of lactate accumulate = OBLA

Question 3

OBLA

Answer 3

• OBLA = when the conc of lactate is around 4mmol per litre
• constantly producing lactate -> RBC activity at low intensities
• measuring OBLA indicates the endurance capacity
• some athletes can work at higher levels of intensity then others before OBLA & can delay when the threshold occurs

Question 4

Lactate threshold

Answer 4

• expressed as a % of the Vo2 max
• as fitness increases the lactate threshold is delayed
  (Average performers = lactate threshold is 50-60% of Vo2 max, elite performers = 70-90%)
• the fitter you are, the higher the lactate threshold as a percentage of our Vo2 max - harder you can work

Question 5

Factors affecting the rate of lactate accumulation

Answer 5

1. Exercise intensity
2. Muscle fibre type
3. Rate of blood lactate removal
4. The respiratory exchange ratio
5. Fitness of the performer

Question 6

Exercise intensity

Answer 6

• the higher the Ex intensity the greater the demand for energy (ATP) - faster OBLA occurs
• when glycogen is broken down in the absence of o2 -> pyruvic acid, L.A is formed

Question 7

Muscle fibre type

Answer 7

• slow twitch produce less lactate than fast twitch
• when slow twitch use glycogen as a fuel (presence of o2) the glycogen can be broken down more efficiently + little lactate production

Question 8

Rate of blood lactate removal

Answer 8

• if rate of lactate = rate of lactate production, the conc of blood lactate remains constant
• if lactate production increases = lactate start to accumulate in the blood until OBLA reached

Question 9

Respiratory exchange ratio

Answer 9

• ratio of Co2 produced compared to o2 consumed
• as the ratio has a value close to 1:0, glycogen becomes the preferred fuel and there is a greater chance of accumulation of lactate

Question 11

Fitness of performer

Answer 11

• training regularly = better chance of delaying OBLA as adaptions occur to trained muscles
• increased no. Of mitochondria, myoglobin and increased capillary density, improves the capacity for aerobic respiration.
• therefore avoid the use of lactate anaerobic system

Question 12

Lactate - producing capacity and sprint / power performance

Answer 12

• elite sprinters and power athletes have adapted to cope with higher levels of lactate
• buffering -> increase the rate of lactate removal
  -> buffering, acts like a sponge mopping up the lactate in the body - work at higher intensities for longer before fatigue sets in
• more adaptions = greater no. and size of mitochondria & the associated oxidative enzymes, increased capillary density and more myoglobin.