Energy Flashcards
Turnover explained
- Molecules constantly used (degraded) and restored (synthesized)
- Catabolism & anabolism process eg energy turnover
Energy currency of cells
ATP - adenosine triphosphate (24kj per mol atp)
GTP - guanosine triphosphate
UTP - uridine triphosphate
ATP breakdown process
- Done w/ ATPases releases energy (is a hydrolysis reaction)
- energy used for cellular processes
ATP equation
ATP + H20 –> (ATPase) –> ADP + P + Energy
ATP homeostatsis
- Maintenance of constant intracellular ATP level
- degradation and resynthesise at equal rates
- energy from food used to reform ATP to then produce more
3 activity levels
Power - 3 secs, immediate, atp, pcr anaerobic
Speed - 60 secs, rapid, msc glycogen & glucose anaerobic
Endurance - > 2min, prolonged, glycogen, glucose, lipid aerobic
Rates of ATP use in exercise
Jogging (50% vo2 max) = 1 (mmol ATP/kg dm/s)
Running (100%) = 2
Sprinting (180%) = 3.6
maximal isometric contraction = 12
ATP supply from different sources - ATP
Concentration (mmol/kg) - 24
Max resynthesise rate (mmol/s) - n/a
Time to depletion - 2s
ATP supply from different sources - PCR
Concentration - 80
Max resynthesise rate - 9
Time to depletion - 8s
ATP supply from different sources - Glycogen -> lactate
Concentration - 300
Max resynthesise rate - 4.5
Time to depletion - 6 min
ATP supply from different sources - Glycogen -> Co2 + H20
Concentration - 300
Max resynthesise rate - 2
Time to depletion - 100 min
ATP supply from different sources - Fat
Concentration - Large
Max resynthesise rate - 1
Time to depletion - days
PCr reaction + explanation
PCr + ADP –> (Creatine kinase) –> ATP + Cr
- High energy phosphorylated compound provides reserve energy to regen ATP (PCr -> Cr + Pi + energy) then (Pi + ADP + energy = ATP)
Myokinase reaction + explanation
2ADP -> ATP + AMP
- converts ADP back to ATP and makes AMP, only relevant in high intensity exercise
ATP, ADP, AMP concentration roles
- ATP conc are poor signals for metabolic control AMP conc are powerful signals
- AMP presence activates ADP restoration to ATP
Importance of graph analysis of energy systems
- ATP doesn’t change much
- AMP does change a lot so is a good regulator for exercise
Energy charge equation
Energy charge = [ATP] + 0.5[ADP] / [ATP] + [ADP] + [AMP]
Energy charge = how much potential energy is in the cell
Energy charge values
1 = maximum, meaning all adenylates are in ATP
Average is 0.90-0.95
0 = all ATP hydrolysed to AMP
AMP deamination
AMP is deaminated (AMP deaminase) to IMP to prevent build up and subsequent reduction in energy charge
Overall = ^ energy charge & continued contraction
IMP destiny
IMP -> inosine -> Hypoxanthine (then leaves muscle = loss of potential energy (bad))
Or turn it back into AMP using GTP which is better
Integration of pathways theory
Old concept - systems used one after the other
New concept - overlap of all systems dependant on length of exercise (ATP, PCr, Anaerobic, Aerobic order)
Power output in Wingate test
23-28% PCr
49-56% Glycolysis
16-18% Oxidative metabolism
Fuel and energy source differences
- Fuel sources (PCr, CHO) can be depleted energy sources (ATP) cant
Energy expenditure (3) & efficiency
Mechanical, Electrical, Heat
- 15-20% efficient
Gross efficiency
(Work accomplished / energy expended) x 100
Net efficiency
REE = resting energy expended
(Work accomplished / energy expended - REE) x100
Work efficiency
(Work accomplished / energy expended - EE unloaded) x 100
Delta efficiency
(change in work accomplished / change in EE) x 100
Energy values of food
Lipid - 9.45 kcal per gram
CHO - 4.3
Protein - 5.65
Alcohol - 7
Energy content & % digestibility
Lipid - 95% = 9 kcal
CHO - 97% = 4
Protein - 92% = 4
Alcohol - 100% = 7
Energy balance (in/out)
In - Food (Lipid, CHO, Protein), Alcohol
Out - Basal metabolism 60-75%, Thermogenesis 10%, PA, 15-30%
Energy balance & body weight
Total daily energy intake (TDEI) = Total daily energy expenditure (TDEE) = stable weight
TDEI > TDEE = weight gain
TDEI < TDEE = weight loss
Components of energy expenditure
PA (physical activity) (highly variable)
BMR (basal metabolic rate)
TEF (thermic effect of food)
energy expenditure during rest
Skeletal muscle - 18% Liver - 27% Brain - 19% Heart - 7% Kidney - 10%
Measuring energy expenditure - Direct calorimetry chamber
- small insulated chamber
- change of water of temp in pipes from heat given off gives energy used
- air filtered & analysed
- expensive, needs specialists & boring
Measuring energy expenditure - Respiration chamber
- no heat exchange, just measuring gas changes
- control what goes in and out of box
- expensive, needs specialists & boring
Measuring energy expenditure - Douglas bag/ breath by breath systems
- measuring a gas sample, use equations to work out energy expenditure
gas collection to energy expenditure equation
1L O2 = 5kcal
0.25L O2 per min x 60 (an hour) = 75 kcal burned
Indirect calorimetry calculations (other methods)
- Heart rate (fitbit ect) (inaccurate)
- Accelerometers ( potentially inaccurate but can be used by specialist)
- Questionnaires (relying on honestly & recall)
Doubly labelled water (has a heavy hydrogen & oxygen)
- allows heavy isotopes to be traced
- Isotopes excreted
- CO2 production = difference in H & O isotope excretion
More O = ^ EE (in free living)
very expensive
Energy cost of different activities
V light activities - 3-5 (min energy cost kcal light - 5-7 moderate - 7-9 strenuous - 9-13 V strenuous - >13
Energy cost of running
1 kcal per kg BM per km
Distance & BM determine kcal burned
Upper limit of energy expenditure
9000 - 11000 kcal per day
Low energy intake in some atheletes
- V low intake despite training
- low EI = decrease TEF % RMR
- negative energy balance = reduced RMR (food efficiency)
Lower limits of energy intake
- 1000-1500 kcal a day (w/ exercise)
- loss of muscle
- anaemia
- decrease BM
- low bone mineral density
- secondary amenorrhea
Energy intake collection methods - 24h recall
- remember everything from last day (hard)
- trained interviewer needed
Energy intake collection methods - food dairies
- 3/7 days
- weighed or not
- write everything
- clear instructions
Energy intake collection methods - food frequency quetionnaire
- not used for accurate measuring
- wider population (larger data pool)
- how often do you eat certain foods
Energy intake collection methods - Diet history
- general
- what have you eaten in the past
