Lecture 12 - Limitations To Exercise

Question 1

Define VO2 max

Answer 1

The maximum rate at which the body can effectively use oxygen during exercise, used as a way of measuring a person’s individual aerobic capacity.

Question 2

What is the respiratory quotient?

Answer 2

VCO2/VO2

V is rate of consumption/production per minute

Question 3

When is rate of oxygen/carbon dioxide exchange not the same as usage/release at tissues?(3)

Answer 3

Hyperventilation (excess CO2)

Exhaustive activity (increase in CO2 due to presence of H2CO3 resulting from lactate buffering)

Gluconeogenesis (making glucose from non carb precursors, especially by liver/kidneys using aminos from proteins, glycerol from fats or lactate from muscles during anaerobic glycolysis)

Question 4

Define RQ vs RER

Answer 4

RQ - indicator of substrate use, can’t exceed 1
RER - respiratory exchange ratio which reflects exchange of CO2 and O2 and can exceed 1, especially during strenuous exercise

Question 5

Contrast submaximal activity and maximal activity

Metabolic rate * with exercise *

Answer 5

Submaximal - heart rate is 50-80% of maximum, VO2 max not reached
Maximal - VO2 max reached

Increases; intensity

Question 6

What are the two deviations to submaximal activity?

Answer 6

1) slow component of VO2 uptake kinetics - at high output, VO2 continues to increase and there’s more type 2 recruitment which is less efficient. If you exercise above lactate threshold, there’s an increase in O2 uptake as requirement greater. Element of using more oxygen than needed
2) VO2 drift - upward drift during prolonged submaximal activity, possibly due to increase in ventilation and catecholamines e.g adrenaline.

Question 7

At maximal activity, what happens to oxygen consumption?

Answer 7

It no longer increases with an increase in intensity

Question 8

VO2 max * after 8-12 weeks of *

More * allows athlete to compete at ** of **

Answer 8

Plateaus; training

Training; higher percentage; VO2 max

Question 9

How do you measure anaerobic contribution to exercise?

Answer 9

1) EPOC (excess post exercise oxygen consumption)
2) Lactate threshold
3) Economy of effort

Question 10

Define lactate threshold

Answer 10

The max effort or intensity an athlete can maintain for an extended time period with little or no increase in lactate
Point when blood lactate production exceeds the body’s ability to clear lactate

Question 11

What are the limits to VO2 max?

Answer 11

1) central physiological functions - pulmonary diffusion, cardiac output and blood oxygen carrying capability (volume and flow)
2) Peripheral physiological functions - muscle diffusion capacity, mitochondria enzyme levels and capillary density

Question 12

Define EPOC

Answer 12

Amount of oxygen required to restore your body to homeostasis post exercise

Question 13

What are the components of EPOC?

Answer 13

Reoxygenation of blood
Replenishment of energy stores (ATP-PCr, glycogen, lactate clearing)
Decrease in circulatory hormones (adrenaline/NA)
Decrease in body temperature
Decrease in heat rate and ventilation to clear carbon dioxide from body

Question 14

What does oxygen deficit accrue even at low intensity?

Answer 14

Because oxygen needs and supplies differ

Question 15

Lactate lowers * of blood, and is taken to * for conversion back to * during exercise recovery

When carbonic acid is in blood, what happens when it gets broken into CO2 and water?

Answer 15

pH, liver; pyruvate

CO2 gets removed at the lungs

Question 16

What are the four key steps of endurance training?

Answer 16

Activity of intensity higher than critical threshold
Sufficient duration
Repeated
Rest-recovery period when adaptations occur

Question 17

What seven things can endurance training accomplish?

Answer 17

Increases VO2 max
Increase muscle fibre sizes and capillaries
Increases citric acid cycle enzymes
Enhances O2 diffusion into muscle
Increase mitochondrial content
Increases max O2 delivery 
Increases plasma volume and CO2 max

Question 18

Describe acute soreness (strain)

Answer 18

During/after strenuous/novel exercise
Accumulation of metabolic byproducts (H+)
Causes oedema - muscle swelling
Disappears within minutes to hours

Question 19

Describe delayed onset muscle soreness (DOMS)

Answer 19

24/48h post exercise
Range from stiff to severe
Major cause is eccentric contractions e.g running downhill
NOT caused by increase in blood lactate concentration!!!!!

Question 20

What is the structural theory of DOMS?

Answer 20

Onset of DOMS parallels onset of enzyme increase; damage indicated by muscle enzymes e.g creative kinase in blood. Also, Z disk myofilament is damaged after eccentric work

Question 21

What is the inflammation theory of DOMS?

Answer 21

Connection between inflammation and soreness, and WBC’s increase with soreness (WBC’s normal role is defence). Substances released initiate inflammation, and damaged muscle cells attract neutrophils which release attractant chemicals/radicals. The released substances stimulate pain nerves and macrophages remove cell debris

Question 22

What is the sequence of events in DOMS? (6)

Answer 22

1) high tension in muscle leads to structural damage to muscle and its cell membrane
2) membrane damage disturbs calcium homeostasis in injures fibre, which inhibits cellular respiration
3) calcium activated enzymes that degrade Z disks
4) neutrophils circulate
5) products of macrophage activity and intracellular contents (e.g histamine) accumulate outside cell, which stimulates pain in free nerve endings (worse with eccentric exercise)
6) fluid and electrolytes move into the area, creating oedema

Question 23

What are the three factors that cause loss of strength due to DOMS?

Answer 23

Loss of contractile protein
Failure in excitation contraction coupling
Physical disruption of muscle

Question 24

How can you reduce DOMS? (3)

Answer 24

Minimise eccentric work early in training
Start low intensity with gradual increase OR
Start high intensity with exhaustive training so soreness decreases later on instead

Question 25

DOMS is important to * muscle *

Answer 25

Stimulate; hypertrophy

Question 26

Compare the two types of muscle cramps

Answer 26

Heat cramps - associated with large sweat/electrolyte losses; treatment is high NA solution, ice and massage

Exercise associated muscle cramps (EAMC) - during/after exercise, fatigue causes altered neuromuscular control and leads to excitation of muscle spindle and inhibition of Golgi tendon organ; relieved by stretching