Bioenergetics and energy metabolism

Question 1

Metabolism

Answer 1

Chemical Reactions, pathways that result in synthesis or breakdown of molecules

Question 2

Bioenergetics

Answer 2

Metabolic processes involved in converting food sources into biologically usable energy.

Question 3

EE rises by around what from rest to exercise

Answer 3

15-25 x

Question 4

VO2

Answer 4

ability to deliver and use oxygen

Question 5

Physiological factors influencing VO2

Answer 5

1. Delivery of oxygen to working muscles: Cardiorespiratory system
2. Utilization of oxygen by working muscles: Metabolic system (Aerobic)

Question 6

Two types of factors that influence O2 consumption

Answer 6

Central and Peripheral

Question 7

Central Factors

Answer 7

Cardiac output which is:
Heart Rate
Stroke Volume (Training improves this)

Cardiac output = Heart Rate x Stroke Volume

Question 8

Peripheral Factors

Answer 8

Extraction by tissues (a-vO2)

Oxygen carrying storage capacity & ability for cells to take O2 
Training increases (3)
-Capillary density 
-Mitochondria number
-Hb, Mb

Question 9

When exercising systemic changes happen because

Answer 9

Muscle demand increases force/speed of muscle contraction

1. Rate of cross-bridge cycling
2. Recruitment of motor units
3. Recruitment of different fiber types

Question 10

Increased in rate of energy system pathways are supported by: (3)

Answer 10

1. Respiratory Changes: increase in ventilation
2. Cardiovascular changes: increase in q (HR x SV)
   Vasodilation in working muscle
3. Muscle Changes: increase Ca release/uptake by SR
   Increase myoglobin shuttling

Question 11

Order of Energy Systems starting up

Answer 11

Creatine phosphate (alactic)
Lactic (glycolysis)
lastly aerobic

Question 12

When our cells have a choice of the three energy systems for ATP synthesis what is our go to system? Why?

Answer 12

Go to system always aerobic

Question 13

Anaerobic lactic system

Answer 13

Involves glycolysis only
Takes place in cytoplasm- close to contractile unit of muscle
Safety valve for the aerobic energy system for when O2 isnt available or ATP is being demanded at a greater rate than the aerobic system can supply itself

Question 14

CP-ATP system (Anaerobic Alactic)

Answer 14

CP in cell is 4-6X greater than ATP
CP is a high energy phosphate reservoir (last 8-12 seconds in an untrained individual, highly trained 15)
Crucial during transition from low to high energy demand.

Question 15

Process of CP system

Answer 15

CP-> C+Pi+ Energy (Creatine Kinase enzyme)

ADP + Pi + Energy -> ATP (ATPase enzyme)

Question 16

What is the power and capacity of each system

Answer 16

1. Alactic: Highest power, lowest capacity (run out of creatine phosphate) need to resynthesize or cannot use energy system again
2. In the middle
3. Aerobic: lowest power, highest capacity

Question 17

Power

Answer 17

Rate at which an energy system can produce ATP

Question 18

Capacity

Answer 18

Total amount of ATP than an energy system can produce

Question 19

O2 Deficit

Answer 19

Difference between oxygen uptake in the first few minutes of exercise and an equal time period after steady state has been obtained.

Question 20

Factors contributing to excess post exercise oxygen consumption (6)

Answer 20

1. Resynthesis of PC in muscle
2. Lactate conversion to glucose
3. Restoration of muscle and blood oxygen stores
4. Elevated body temperature
5. Post-exercise elevation of HR and Breathing
6. Elevated Hormones

Question 21

How we get CrP stores back

Answer 21

ATP -> ADP + Pi + Energy
——–>
C + Pi + Energy –> CP

Question 22

Resynthesis of CP stores

Answer 22

15s - 68.7 %
60s - 81.0 %
180s - 92.0 %

For every second worked about 10-12 seconds of recovery is needed.

Question 23

Control Systems during exercise

Answer 23

Demands for energy vs Supply of Energy

Question 24

Energy Demand

Answer 24

How much energy is needed
What intensity is the muscle working
How long has the muscle been working at intensity (duration)

Question 25

Energy Supply

Answer 25

What fuels are available | Can metabolic process supply ATP at a high enough rate

Question 26

Short term high intensity =

Answer 26

Greater contribution of anaerobic energy systems

Question 27

Long term, low to moderate intensity

Answer 27

Majority ATP produced aerobically

Question 28

Energy Requirements at Rest

Answer 28

``` Almost 100% of ATP produced by aerobic metabolism Blood lactate levels are low Resting O2 consumption 0.25 L/min 3.5 ml/kg/min ```

Question 29

Rest to Exercise Transitions

Answer 29

ATP production increases immediately Oxygen uptake increases rapidly (Reaches steady state within 1-4 minutes) Initial ATP production anaerobic Oxygen deficit

Question 30

Steady State reached means

Answer 30

ATP requirement is met through aerobic ATP production.

Question 31

Trained subject have lower Oxygen Deficit why?

Answer 31

Better developed aerobic bioenergetic capacity CVD and muscular adaptations = Results in less production of lactate and H+

Question 32

Recovery from Exercise

Answer 32

``` Oxygen uptake remains elevated above rest during recovery from exercise Oxygen debt (repayment for O2 deficit at onset of exercise) EPOC - terminology reflects only 20% elevated o2 consumption used to repay O2 deficit. ```

Question 33

Rapid portion of O2 debt

Answer 33

1. Resynthesizes stored PC | 2. Replenshes muscle and blood O2 stores

Question 34

Slow Portion of O2 debt

Answer 34

1. Elevated heart rate and breathing= increases energy need 2. Elevated body temperature= Increases in metabolic rate 3. Elevated epinephrine and norepinephrine= Increase in metabolic rate 4. Conversion of lactic acid to glucose (gluconeogenesis)

Question 35

Why EPOC greater following high intensity exercise

Answer 35

1. Higher body temperature 2. Greater depletion of PC (additional 02 required for resynthesis) 3. Greater blood concentrations of lactic acid (additional o2 required for greater level of gluconeogenesis) 4. Higher levels of blood epinephrine and norepinephrine.

Question 36

Removal of Lactic Acid following exercise

Answer 36

70% of lactic is oxidized by cells (Used as a substrate by heart and skeletal muscle) 20% converted to glucose 10% converted to amino acids

Question 37

Lactic Acid removed more rapidly from blood if

Answer 37

Light exercise performed during recovery. | Optimal intensity is 30-40% VO2 max.

Question 38

Metabolic Responses to Short Term High Intensity Exercise

Answer 38

First 1-5 Seconds of exercise: ATP produced via ATP-PC system Intense exercise longer than 5s: Shift ATP production via glycolysis Events lasting longer than 45 seconds: All three systems 60s: 70% anaerobic, 30% aerobic 120s: 50% anaerobic, 50% aerobic

Question 39

Metabolic responses to prolonged exercise (>10 minutes)

Answer 39

ATP production primarily aerobic Steady state O2 uptake maintained during submax exercise Hot Humid environment or High intensity: Upward drift in O2 uptake over time from increase in body temp and increases blood levels of epinephrine and norepinephirne.

Question 40

Lactate Threshold

Answer 40

Point at which blood lactic acid rises systematically during incremental exercise Appears 50-60% VO2 max in untrained individuals 65-80% in trained subjects Also called: Anaerobic threshold OBLA (When blood lactate levels reach 4 mmol/L)

Question 41

Reasons for Lactate Threshold (4)

Answer 41

1. Low muscle oxygen (hypoxia) 2. Accelerated glycolysis: -NADH produced faster than it is shuttled into mitochondria - Excess NADH in cytoplasm converts pyruvic acid to lactic acid. 3. Recruitment of fast twitch muscle fibers: LDH isozyme in fast fibers promotes lactic acid formation 4. Reduced rate of lactate removal from the blood: Liver removes lactate from blood.

Question 42

Practical Uses of Lactate Threshold

Answer 42

Prediction of Performance (Combined with exercise economy) | Planning training programs (marker of training intensity, choose a training HR based on LT)