LEWIS: Oxygen Consumption Flashcards Preview

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Flashcards in LEWIS: Oxygen Consumption Deck (60):
1

Oxygen consumption is the

amount of oxygen used by the body to produce ATP

2

Begin to exercise we need more ATP and therefore use more oxygen so our

oxygen consumption increases

3

VO2 max is the

maximum amount of oxygen consumed and utilised by the body per minute

4

When the amount of oxygen consumed is lower than the amount actually required there is an

oxygen deficit

5

Oxygen deficit is when

insufficient oxygen is available at the start of exercise to provide all the ATP needed aerobically

6

Exercise = more oxygen consumed than at rest in order to supply mitochondria in muscle fibres so that they can manufacture ATP aerobically, if the level of exercise intensity increase, so does the level of oxygen uptake. This relationship continues, until during extreme exercise, we reach a level of

maximum oxygen consumption

7

Maximal oxygen consumption (VO2 max) is used to refer to the

maximum amount of oxygen that an individual can consume and utilise per minute during strenuous exercise

8

Oxygen consumption depends on many factors, such as:

fitness
weight
percentage body fat
gender

9

VO2 max is usually regarded as an accurate indication of the athlete's stamina as it estimates directly how much oxygen the athlete has available for

ATP resynthesis

10

VO2 max is linked to

OBLA/Lactate threshold

11

OBLA gives an indication of

endurance capacity

12

OBLA is expressed as a

percentage of VO2 max

13

Average untrained person will work at about what percentage of their VO2 max before OBLA occurs?

50-70%

14

Trained endurance performer will work at about what percentage of their VO2 max before OBLA occurs?

75-90%

15

Lactate is produced when hydrogen is removed from the

lactic acid molecule

16

OBLA is the

point at which lactate starts to rapidly accumulate in the blood

17

At rest lactic acid in the blood is

1-2mmol-1

18

During intense exercise the lactic acid in blood is

4mmol-1

19

If the level of exercise is submaximal the oxygen consumption reaches a

steady state

20

steady state is the period of exercise when oxygen consumption matches

the amount needed by the body to produce the ATP required for that level of exercise

21

Oxygen consumption is measured by subtracting the volume of oxygen expired during a period of time from the

volume of oxygen inspired during the same time period

22

A direct method of VO2 max measurement is:

Treadmill run/cycle ergometer workload is increased every 2-3 minutes
-Oxygen consumption will rise during each stage
-Runner unable to continue owing to exhaustion = reached their aerobic capacity
-Amount of oxygen being consumed in these final few seconds of exercise is then measured to give a VO2 max value

23

Factors affecting VO2 max:

GENDER
AGE
LIFESTYLE
TRAINING
BODY COMPOSITION
GENETICS

24

Gender affects VO2 max:

-Male bigger (70mlkg-1min-1) than female [20% lower VO2 max] (60mlkg-1min-1)

25

VO2 max is lower in females than males, as females have a:

-Smaller left ventricle, smaller stroke volume
-Lower maximum cardiac output
-Lower blood volume, resulting in lower haemoglobin levels
-Lower tidal and ventilatory volumes

26

Age affects VO2 max as:

-max HR drops (5-7 bpm per decade)
-increase in peripheral resistance results in a decrease in maximal stroke volume
-blood pressure increases both at rest and during exercise
-Less air is exchanged in the lungs due to a decline in vital capacity and an increase in residual air

27

Lifestyle affects VO2 max due to

-smoking
-sedentary lifestyle
-poor diet
-body fat percentage

28

VO2 max can be improved by up to what percentage following a period of aerobic training (continuous, fartlek, aerobic interval)

10-20%

29

19 physiological adaptations following aerobic training, which improve VO2 max, are:

1-increased max cardiac output
2-increased stroke volume/ejection fraction/cardiac hypertrophy
3-greater HR range
4-less oxygen being used for heart muscles, more available for other muscles
5-increased A-VO2 diff
6-increased blood volume and haemoglobin count
7-increased glycogen and triglyceride stores
8-increased myoglobin content
9-increased capilliarisation (lungs and muscles)
10-increased number and size of mitochondria
11-increased concentrations of oxidative enzyme
12-increased lactate tolerance
13-reduced body fat
14-slow twitch hypertrophy
15-increased venous return
16-bradycardia (reduction in resting HR)
17-decrease in lactic acid accumulation
18-increased enzyme efficiency
19-improved transfer of oxygen to mitochondria via myoglobin

30

Body fat percentage/composition affects VO2 max as:

VO2 max decreases as body fat percentage increases

31

Causes of fatigue depend upon

intensity and duration of the activity

32

7 causes of fatigue:

1-glycogen depletion
2-lactic acid build up
3-reduced rate of ATP synthesis
4-dehydration
5-reduced levels of calcium
6-reduced levels of acetylcholine
7-thermoregulation

33

Glycogen depletion causes fatigue and is known as 'hitting the wall' as the body tries to

metabolise fat, but is unable to use this as a fuel on its own

34

Lactic acid build up causes fatigue as it releases hydrogen ions which cause an

increase in acidity in the blood plasma - inhibits enzyme action and therefore the breakdown of glucose

irritates nerve endings causing pain

35

Reduced rate of ATP synthesis causes fatigue as when ATP and PC stores are depleted there is insufficient ATP to sustain

muscular contractions

36

Dehydration causes fatigue as it can have an effect on blood flow to the working muscles and results in a loss of electrolytes, such as calcium, which help with muscular contractions. As a result of dehydration:

-Blood viscosity increase
-Blood pressure decreases
-Reduction in sweating to prevent further water loss, in turn causes increase in body temperature
-Performer unable to meet the demands of the activity

37

Reduced levels of calcium are caused by an increase in hydrogen ions (due to acid build up), as a result calcium ions arent released for

muscle contractions

38

Acetylcholine is a neurotransmitter that can help a nerve impulse to jump the synaptic cleft and initiate muscle contraction. Reduced levels of acetylcholine means that

muscles become fatigued

39

(Thermoregulation) heat is generated during exercise in the body as a result of all the

metabolic processes that occur to produce energy

40

(Thermoregulation) long-disrance runners sometimes experience difficulty with temperature regulation. The heat produced through muscle contraction raises the core body temperature, which causes the

blood viscosity to increase and metabolic processes to slow down - performer is unable to sweat efficiently and dehydration occurs

41

(Thermoregulation) the thermoregulatory centre in the medulla oblongata controls temperature. Heat is transported to the surface of the skin by the blood and the vessels vasodilate, enabling

heat to be lost through radiation, convection or evaporation of sweat

42

(Thermoregulation) Body is dehydrated, total blood volume decreases, more blood is redirected to the skin (to aid cooling) so the amount of blood and therefore oxygen available to the working muscles is reduced and this affects performance. In hot conditions this situation is worsened so it is important to acclimatise, enabling the body to modify the control systems that

regulate blood flow to the skin and sweating

43

Energy continuum refers to the continual movement from one energy system to another depending on the

intensity and duration of the exercise

44

(ENERGY CONTINUUM) the ATP-PC/lactic acid threshold is the point at which the

ATP-PC energy system is exhausted and the lactic acid system takes over.

45

(ENERGY CONTINUUM) the lactic acid/aerobic threshold is the point at which the

lactic acid system is exhausted and the aerobic system takes over

46

(ENERGY CONTINUUM) Thresholds are 'zone' of one of the energy

pathways/systems

47

(ENERGY CONTINUUM) When reaching a threshold a particular energy pathway is no longer able to sustain energy production at the level required and an additional energy pathway will begin to play a more

significant role

48

OBLA is the point where the aerobic energy system cannot supply the energy quick enough and the body has to switch to its

anaerobic processes

49

OBLA is expressed via VO2 max
Untrained =
Trained =


50%
85%

50

Fatigue can be described as the inability of a muscle to maintain contractile force as a result of

repeated contractions

51

OBLA can also occur because the anaerobic lactate energy system produces more lactic acid than can be dealt with and the acid starts to accumulate in the

muscles and blood

52

The switch from a predominantly aerobic supply of energy for resynthesising ATP to anaerobic lactate methods happens because we have

insufficient oxygen in the mitochondria to combine with the hydrogen being released as a result of glucose breakdown

53

The lactate threshold varies for each individual and reflects their ability to

get oxygen into their mitochondria or the performer's VO2 max

54

A exercise intensity increases, oxygen consumption increases until a maximum level is reached, known as the

VO2 max

55

The percentage of your VO2 max that is used befroe you cross the lactate threshold is another determining factor for fatigue as it refers to the

highest rate of work that can be sustained for 20-40 minutes without becoming fatigued

56

Being able to use a higher percentage of your VO2 max (Fractional percentage of oxygen consumption) will raise the

aerobic/anaerobic threshold

57

Untrained will be accumulating lactic acid at a much lower

percentage of VO2 max than trained

58

Lactate tolerance refers to how well the body can withstand the effects of the accumulation of lactic acid in the

muscles and bloodstream and is related to the amounts of bicarbonates within the blood and other bodily fluids

59

(LACTATE TOLERANCE) hydrogen ions that are not combined with oxygen and lactic acid can be combined with bicarbonates which render them

less acidic

60

(LACTATE TOLERANCE) Bicarbonates draw the hydrogen ions and the lactic acid from the muscle cells into the blood, possibly reducing the effects of

fatigue