human energy systems nfsc 303. you will not be required to do the mathematical conversions from one...
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• You will not be required to do the mathematical conversions from one for of energy to another (p. 83-85 of textbook)
How do we measure Calories?• Direct Calorimetry:
– In food: – In humans:
• Indirect Calorimetry:–
• Newer: IDEEA device– Intelligent Device for Energy Expenditure and
Activity– Records body motions every second for 24 hours.
Components of Energy Expenditure
• Energy to support basal metabolism: BEE
• Energy to support physical activity: TEE
• Energy to process food: TEF
Energy to Support Basal Metabolism
• BEE = Basal Energy Expenditure
• (Calculated from BMR = Basal Metabolic Rate)–
– Measured in standard state (no food/exercise for 12 hours; measurement taken right after waking, resting at a comfortable temperature)
– REE/RMR = Resting Energy Expenditure or Resting Metabolic Rate: similar numbers (not standard state)
• Primary factors affecting BMR/BEE:– –
• Other factors: growth, fever, ambient temp., pregnancy, smoking, disease, age, BSA, kcalorie intake–
To estimate BEE:1. Rough estimate: Body weight in pounds X 10
2. More accurate:
Men:
Women:
Example:
BEEBEE
TEFTEF
TEETEE
Tot
al D
aily
En
ergy
Exp
end
itu
re (
kca
ls)
Tot
al D
aily
En
ergy
Exp
end
itu
re (
kca
ls)
Remember: Remember: BMR is BMR is measured 12 measured 12 hours after any hours after any physical physical exercise and in exercise and in a fasted state.a fasted state.
Wide difference in metabolic rates due to genetics...
• But within our individual range…
– lowest would be achieved via
– highest would be achieved with
• Exogenous fuels: from outside the body– dietary protein, CHO, and fat
• Endogenous Fuels: from within the body– – –
• importance increases in times of inadequate kcalories or CHO intake
Energy Metabolism:
All processes involved in the production, storage, and use of energy
• As macronutrients are broken down, E from the breakage of bonds is:– – –
ATP: Adenosine Triphosphate
• A-P~P~P• High-energy bonds
“store” energy• Cleaved to release E
for–
–
• A-P~P / P = ADP• A-P/ P = AMP• To regenerate ATP,
we need a source of P with high energy bonds:– ADP + P
– AMP + 2P
These high-energy bonds will come from:
Phosphocreatine: PCr
• High-E molecule - helps maintain a steady supply of ATP for short bursts of energy– – –
• To keep regenerating ATP:–
Anaerobic Metabolism: Glycolysis
• Glucose (from glycogen) is “split” for E– It is only partially metabolized – will need oxygen to
metabolize it completely.
• Primary source of E during _____________ (when O2 availability is low)
• Takes place in the cytosol of the cell
Aerobic Metabolism: Krebs Cycle and Electron Transport
System (ETS)•
•
•
• Can metabolize fat, carbohydrate (finish the job) and some protein.
So to fuel activity, we need ATP.
ATP is generated by metabolizing our fuel sources: carbohydrate, fat, and some protein.
So how much of each fuel do we use during exercise? (What’s the fuel mix for a given exercise?)
Primary Exercise Fuels: CHO and FAT
• Carbohydrate from ______________
• Fat from ________________
Remember: only CHO can be burned when
oxygen availability is low
Fuel sources used during exercise Depend on:
• Intensity of activity
• Duration of activity
• Fitness level of the individual
• Macronutrient and kcalorie content of diet
• Fuel Sources:– Immediate – ATP/PCr system
– Anaerobic – O2 not required. •
•
• Glycolysis alone can support muscle contraction for ~ 30 seconds to 2 minutes.
– Aerobic – O2 required •
•
•
When Exercise Begins…
• O2 hasn’t gotten to muscles yet
• ATP/CP during first seconds
• Mostly Anaerobic for several minutes
• Then, aerobic (along with anaerobic) for the rest of exercise time.
Fuel sources used during exercise Depend on:
• Intensity of activity
• Duration of activity
• Fitness level of the individual
• Macronutrient and kcalorie content of diet
Exercise Intensity
• VO2Max
• THR range
• RPE
• Mild Intensity Exercise (walking)• • ____________________ are the predominant
fuel for ATP production (Krebs and ETS)• (~60% FA and 40% CHO)
• Moderate Intensity Exercise (ie. Jogging, aerobics)–
–
– Rely on – Therefore, more _________ is used
• (e.g. ~50% CHO/50% Fat)
– The longer the duration, the greater use of ___________ as fuel
– (for exercise lasting several hours, 60-70% energy can be supplied by fat).
• High Intensity Exercise (Strenuous, Intense)
– induces ________________state in muscle cell
–
– Glycolysis can’t be maintained… very intense
ex. only lasts seconds to minutes
Fuel sources used during exercise Depend on:
• Intensity of activity
• Duration of activity
• Fitness level of the individual
• Macronutrient and kcalorie content of diet
Fuel sources used during exercise Depend on:
• Intensity of activity
• Duration of activity
• Fitness level of the individual
• Macronutrient and kcalorie content of diet
• Training Effects of Aerobic Exercise:
LDL (“bad”)cholesterol, HDL (“good”)cholesterol– strengthened heart, lungs– curbed appetite metabolic rate…
• Effects of Strength Training
LDL (“bad”) cholesterol constipation, diverticulosis, hemorrhoids, and poss.
Colon CA• speeds waste through colon
– stronger bones
Fuel sources used during exercise Depend on:
• Intensity of activity
• Duration of activity
• Fitness level of the individual
• Macronutrient and kcalorie content of
diet
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