Exercise Energetics Flashcards
1
Q
How many elements are there?
A
18 elements, 64 naturally occurring on earth
2
Q
What are the 4 most abundant elements?
A
- Oxygen
- Carbon
- Hydrogen
- Nitrogen
3
Q
What are elements?
A
- Chemically homogenous
- Indivisible into simpler substances
- Nuclei all have the same number of protons
- Building blocks of compounds/molecules
4
Q
What is the atomic number?
A
The number of protons of a specific element
5
Q
What is the atomic mass?
A
The number of protons and neutrons in nucleus
6
Q
What’s an Isotope?
A
Same element but different number of neutrons (changes the mass)
7
Q
What is glucose?
A
- 6 carbon molecule, having carbon makes it an ‘organic’ molecule
- Glucose plays a central role in our metabolism and extraction of energy
8
Q
What is electrical charge?
A
- Electrical charge of atom neutral (# of protons and electrons are equal)
- Atoms can gain or lose electrons and become charged
- Electron configuration affects ability to combine/react with other molecules
9
Q
What is a cation?
A
Positively charged ion (lost e)
10
Q
What is an anion?
A
Negatively charged ion (gain e)
11
Q
What are valence electrons?
A
- The outer shell electrons
- An unfilled outer shell means the element is less stable and vice versa
12
Q
What is a chemical reaction?
A
The disruption of existing bonds within reactant molecules and the creation of fresh bonds in product molecules, forming a new substance
13
Q
What is an ionic bond?
A
Where one elements loses electrons and one gains to make a stable compound (electron exchange)
14
Q
What is a covalent bond?
A
Electron sharing (ie. H2O)
15
Q
How does hydrogen release effect acidity?
A
- Acidity is a measure of hydrogen concentration
- Lower pH means more acidic
- The greater the H+, the greater the acidity
- Acids donate protons
- Bases accept protons
16
Q
What is the difference between lactate vs lactic acid?
A
- Whether the hydrogen is linked or not
- Lactate + hydrogen ion = lactic acid
17
Q
What is a buffer?
A
- Can donate or accept H+ to maintain relatively stable pH
- Chemical reactions in our body to allow us to release energy and do everything we need to do.
- Eg. Bicarbonate buffer system
18
Q
What affects acid-base balance in body?
A
- Ingestion foods (meat more acidic)
- Metabolism (Co2 produced)
- Hyperventilation
19
Q
What are 4 functional groups?
A
- CH3 Methyl
- COOH Carboxyl
- OH Hydroxyl
- PO4 Phosphate
20
Q
What is oxidation?
A
The loss of electrons in chemical reactions
21
Q
What is reduction?
A
The gaining of electrons in chemical reactions
22
Q
What are REDOX reactions?
A
Oxidation and reduction coupled together
23
Q
What is catabolism?
A
Breakdown of energy-yielding molecules
24
Q
What is anabolism?
A
Building energy-yielding molecules
25
What is the 1st law of thermodynamics?
Conservation of energy: energy is not lost, its transferred
26
What is the 2nd law of thermodynamics?
Systems go from a higher state to a lower state of potential energy
27
What is free energy?
The energy from a reaction that can be used for work
28
What maintains the electrochemical gradient?
The Na+K+ATPase pump
29
What is ATP?
- A high-energy compound that is used to drive all energy-requiring processes in cells
- Only very small quantity stored in muscle and other cells
30
What are exergonic reactions?
- Downhill processes - releasing energy
- The end product ends up having lower potential energy than the reactants
31
What are endergonic reactions?
- Uphill processes - requiring energy input
- End product has greater amount of potential energy than the reactants
32
What are the factors affecting the rate of energy transfer?
- Mass action
- Enzymes (activity)
- Co-enzymes/co-factors
- Temperature
- pH
- These are often trainable
33
What is mass action?
- Reactions proceed according to product vs substrate
- Mass action ratio = product/substrate
- Can impact on all reactions that it participates in
34
What are enzymes?
- Act as catalysts: they facilitate reactions
- They are re-usable; eventually will denature
- They are substrate specific
- Centrally involved in regulating rate of substrate transformation to match supply with energy needs
35
What are co-enzymes/co-factors?
- Facilitate action of enzymes
- Help bind substrate with enzyme
- Temporary carrier of intermediary products
- The enzyme isn't fully functioning unless it has its co-enzyme
36
How does temperature impact the rate of energy transfer?
- Increase in temperature generally increases activity
- Temperature higher that 40-50 degrees destroys enzymes
37
How does pH affect the rate of energy transfer?
Enzymes have an optimal pH
38
Where is energy stored?
- ATP
- Creatine Phosphate
- Glucose
- Glycogen
- Fatty Acids (triglycerides)
- Amino Acids (protein)
39
Where is creatine phosphate stored?
In muscle; continuously regenerated from free creatine (minutes to regenerate) - Make our own and get it from meat
40
Where is free glucose stored?
In bloodstream, little in muscle; maintained fairly constant, important for central nervous system
41
Where is glycogen stored?
Muscle and liver; muscle first used, liver glycogen first broken down to glucose, into blood, to muscle transported across muscle membrane
42
Where are fatty acids stored?
Muscle (IMTG, IMCL) & adipose tissue; muscle first used, adipose must be broken down and via blood and transported into muscle
43
What are the 3 energy systems?
1. ATP/CP "Phosphagen"
2. Anaerobic Glycolytic
3. Aerobic; glycolytic and lipolytic
44
When do each of the systems deplete?
- CP depletes very rapidly (seconds)
- Anaerobic glycolysis (lactate) depletes glycogen rapidly (minutes)
- Aerobic glycolysis depletes glycogen at a moderate rate (hours)
- Aerobic lipolysis depletes lipids slowly
45
What are the components of total energy expenditure?
- Basal Metabolic Rate (BMR)
- Dietary induced thermogenesis (DIT)
46
What is the relative contribution to daily expenditure of the components of total energy expenditure?
- BMR is the greatest use of energy (60-75%)
- DIT is the least (~10%)
- PA is the most variable (15-30%)
47
What are our typical daily energy needs?
- Altered by weight (FFM), activity
- 1.4 - 2.4 x BMR
- 1500kcal (~6,000kJ) - 3500kcal (~14,000kJ)
- Sometimes expressed in METS
48
Why does energy expenditure drop with older age?
- Losing lean mass
- Less active
- Both affecting their energy utilisation
- Sex hormones start dropping
- The effect of PA is quite large
49
Which factors influence energy balance?
Energy expenditure or energy intake
50
What are the dietary composition affects on satiety?
- Protein > CHO > fat
- Increase in protein and CHO balance increases oxidation
- Nutrient oxidation in peripheral tissues affects satiety
- This order of regulation may underlie the differences in satiety
- High CHO and protein oxidation reflect fed state; high fat oxidation reflects energy deficit
- Theorised that peripheral fuel oxidation changes trigger satiety signals sent to brain
51
What are other factors that affect energy balance?
- Fat mass
- Leptin
- Grehlin
52
What is leptin?
- Appetite depressant (peptide, neurotransmitter)
- Produced by adipose tissue (relative to amount)
53
What is grehlin?
- Appetite stimulant (peptide, neurotransmitter)
- Produced in stomach, pancreas, counteracts leptin
- Has role in brain function, learning, secreted with growth hormone
54
What is EPOC?
- Excess post-exercise oxygen consumption
- This effects intensity and duration
55
How does exercise intensity affect energy expenditure immediately after?
- Greater intensity gives greater EPOC even if total energy expenditure similar in two trials
- Mixing some anaerobic/high intensity exercise with low may be of value to those interested in weight loss
- Increased exercise/activity frequency can also increase EPOC
56
What are some other reasons to include high intensity exercise regarding energy balance?
- Total energy expenditure in given period of time greater
- Often decreased exercise efficiency
- Resistance training builds muscle mass
- Aerobic >70%VO2max increases RMR separate from any change in muscle mass
57
What is the substrate use at rest?
- Aerobic
- Mix of substrates, CHO and fat, diet has large effect
58
Aerobic System - How does exercise duration affect fat and CHO oxidation
- As exercise duration increases, you oxidise more fat
- Carb oxidation decreases - this is affected by whether you have consumed carbs or not (are the glycogen stores maxed out)
59
Aerobic System - How does exercise intensity affect fat and CHO oxidation?
- As exercise intensity increases, you oxidise more CHO
- Fat oxidation decreases
60
What is the rest to exercise transition?
- Even at relatively slow, steady state pace, at onset of exercise aerobic processes cannot fuel exercise immediately
- O2 deficit reflects anaerobic energy provision
- Lag - O2 supply to muscles mitochondria, enzyme activity, inertia of system
61
Where is the phosphagen system located?
In the cytosol of the cell
62
What is the fuel for the phosphagen system?
ATP and creatine phosphate
63
What happens in the phosphagen system?
- ATP splits into ADP + Pi which releases some energy: use that energy to reattach the ADP to reform ATP and then the cycle continues
- Also, break the phosphagen off the creatine which releases energy
- Energy is utilised quickly and lasts for about 5 seconds
64
What is the alternate pathway of the phosphagen system when CrP is depleted?
- Uses adenylate kinase to take 2 ADPs and makes 1 ATP and 1 AMP
- This is limited and not very efficient
65
What is AMP?
- Signalling Molecule
- Upregulates substrate release, glycolysis, ATP from other energy systems anaerobic glycolytic and aerobic
66
Where does creatine come from?
- Synthesised in kidneys (& liver) - from 3 amino acids
- From meat
- Vegetarians may have less in muscles or synthesise more
- Continually recycled
67
Where are the three places glucose comes from?
- From breaking down of glycogen in muscle
- Released into the bloodstream from liver
- From gut absorption from meal into circulation via portal vein
68
What is glycogenolysis?
The breakdown of glucose
69
What is gluconeogenesis?
Making new glucose
70
What are the 2 parts of glucose metabolism?
- Anaerobic (glycolysis)
- Aerobic (krebs cycle/electron transport chain/oxidative phosphorylation)
71
Where is glycolysis located?
In the cytosol of the cell
72
What is the fuel for glycolysis?
Carbohydrates (glycogen or glucose)
73
What is the difference between glycolysis and glycogenolysis?
- Glycolysis = catabolism of glucose to pyruvate
- Glycogenolysis = removal of individual glucose units from glycogen
74
What happens in stage 1 of glycolysis?
- Anaerobic or O2 independent
- Need ATP to activate it and then once you have 6 phosphates you can do the reaction and get 2 pyruvate
- = Net 2 ATP
75
What happens in stage 2 of glycolysis?
- Aerobic or O2 dependent
- The pyruvate can get converted to lactate or gets acted on by the enzyme from the mitochondrial membrane and get converted into Acetyl CoA
- = Net 30-32 ATP
76
What is NAD+?
- A co-enzyme for key enzymatic reactions in glycolysis
- Oxidation of NADH
- Forms a gradient on one side of the mitochondrial membrane which allows energy to capture
- We need NAD to make reactions run
77
What needs to happen regarding the rate of NADH being reconverted into NAD?
The rate of NADH being reconverted into NAD in the electron transport chain needs to keep up with the rate of NADH production in glycolysis to keep breaking down the pyruvate.
78
What happens in anaerobic glycolysis?
- Reduction of pyruvic acid to lactic acid which oxidises the NADH, reforming NAD
- This reaction increases with increasing energy demands
79
What is LDH?
A bi-directional enzyme
80
What happens at rest after exercise?
- Tissue can re-form pyruvate from lactate
- As intensity drops to a level at which NADH can be oxidised, lactic acid is oxidised back to pyruvic acid which allows the oxidative metabolism of pyruvate to proceed
81
What is the rate of glycogen use in anaerobic glycolysis?
- Inefficient; fewer ATP/mole glucose; but rate of ATP released greater
- Therefore, higher intensity exercise fuelled by anaerobic glycolysis requires exponential increase in glycogen use
- Anaerobic glycolysis can deplete muscle glycogen rapidly
82
How much glycogen is stored in the muscle?
~300g
83
How much glycogen is stored in the liver?
~100g
84
How much glucose is stored in the blood?
~10g
85
What is the total store of CHO?
- ~ same as daily CHO intake
- ~8.4mJ energy
86
How much lipids are stored in the body?
- Total store is ~10000g
- There's more than twice the energy per gram per gram of lipid than CHO
- Energy store is ~420mJ
87
What performance factors limit the availability of glycogen?
- Intensity, duration
- Previous exercise, recovery time
- Diet - amount CHO glucose or glucose precursors
88
How does exercise intensity effect the rate of CHO metabolism?
Increasing exercise intensity increases the rate of CHO metabolism
89
What is GLUT-4?
- The transporter that gets glucose into the muscle and it doesn't take ATP as its facilitated transport, not active.
- Contraction acutely upregulates this
- Training increases the total amount there is
90
Where are triglycerides stored?
Mostly in the adipose tissue but also in the muscle (Intramuscular triglycerides IMTG - more readily available)
91
What are triglycerides?
- The storage form of lipids
- Enzyme splits it into 3 fatty acids and glycerol so they can enter the bloodstream
92
How much ATP does 3 molecules of 18-C FFA yield?
441 ATP
93
How much ATP does 1 molecule of 3-C glycerol yield?
19 ATP
94
How much ATP does a triglyceride yield in total?
460 ATP
95
What is the process of lipid metabolism from adipose tissue?
Mobilisation --> Circulation --> Uptake --> Activation --> Translocation --> B Oxidation --> Krebs cycle and electron transport
96
What does the rate of adipose tissue blood flow depend on?
- Moderate intensity increases the blood supply to the adipose tissue
- High intensity causes vasoconstriction which reduces the blood supply to the adipose tissue
97
If starting from IMTG, where do you start in the metabolism process?
- Start at activation (needs to get activated across the mitochondria)
- Still need to split the free fatty acids as its still stored as triglycerides
98
How do fatty acids get across the mitochondrial membrane?
- They need to get activated and translocated which takes time and ATP
- Carnitine is very important for this
99
What is beta oxidation?
- The 1st stage in metabolising/breaking down free fatty acids
- This uses acetyl CoA
- Results in the release of FADH and NADH
100
What is the process of amino acid metabolism?
Amino acids are all different and some are metabolised like fat, others like glucose.
101
What is the protein metabolism like during and after exercise?
- During exercise, we are catabolic because our body needs energy, in an hormonal state
- After exercise, we are anabolic and are building the muscle/protein in response to exercise
102
Is protein metabolism affected by CHO availability?
Amino acids can be used as glucose and because of that, the oxidation of those amino acids is very much affected by CHO (glucose) availability
103
What does the liver do to substrates?
- Converts substrates into others
- Some amino acids into other amino acids
- Some amino acids, glycerol and lactate into glucose
104
What is a notable exception to interconversion?
That free fatty acids can't be used to generate glucose (not a source for gluconeogensis)
105
What can maximise energy availability?
A shuttling of metabolites around different organs
106
What is an important determinant of use for fat and other fuel stores?
The amount in the muscle
107
How does training increase the amount of glycogen stored?
- Because when we exercise we deplete the muscle glycogen so therefore the muscle will respond by storing more when we rest (the more you have, the more you can use)
- Therefore, a trained individual has higher glycogen stores
108
How does training effect the rate of energy provision?
Adaptations occur with training which alter substrate use at a given intensity and allow for a greater rate of energy provision and duration at a given intensity
109
How does a trained individual use their aerobic and anaerobic systems?
Can use aerobic system at a much higher intensity (ability to get more ATP out of it) and therefore use the anaerobic less at a given sub maximal intensity
110
How does training status affect CHO oxidation?
Training status can increase the power and capacity of CHO oxidation as well as the total amount being utilised
111
