Human energy systems
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Human Energy Systems. NFSC 303. You will not be required to do the mathematical conversions from one for of energy to another (p. 83-85 of textbook). Energy Balance = “energy in” vs. “energy out” Energy in: Energy out: . How do we measure Calories?. Direct Calorimetry: In food:

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Human Energy Systems

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Human energy systems

Human Energy Systems

NFSC 303


Human energy systems

  • You will not be required to do the mathematical conversions from one for of energy to another (p. 83-85 of textbook)


Human energy systems

Energy Balance = “energy in” vs. “energy out”

Energy in:

Energy out:


How do we measure calories

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

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

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)


Human energy systems

  • Primary factors affecting BMR/BEE:

  • Other factors: growth, fever, ambient temp., pregnancy, smoking, disease, age, BSA, kcalorie intake


Human energy systems

To estimate BEE:

  • Rough estimate: Body weight in pounds X 10

  • More accurate:

    Men:

    Women:

    Example:


Energy to support physical activity

Energy to Support Physical Activity

  • TEE = Thermic Effect of Exercise


Energy needed to process food

Energy Needed to Process Food

  • TEF = Thermic Effect of Food


Human energy systems

Total Daily Energy Expenditure (kcals)

TEE

TEF

Remember: BMR is measured 12 hours after any physical exercise and in a fasted state.

BEE


Wide difference in metabolic rates due to genetics

Wide difference in metabolic rates due to genetics...

  • But within our individual range…

    • lowest would be achieved via

    • highest would be achieved with


Fueling activity

Fueling Activity


Human energy systems

  • 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

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:

ATP: Adenosine Triphosphate


Phosphocreatine pcr

Phosphocreatine: PCr

  • High-E molecule - helps maintain a steady supply of ATP for short bursts of energy

  • To keep regenerating ATP:


Metabolic pathways

Metabolic Pathways

  • Take place in the cytosol and mitochondria of the cell


Human energy systems

  • Anabolic Pathways:

  • Catabolic Pathways:

  • Anaerobic:

  • Aerobic:


Overview of pathways

Overview of Pathways


Anaerobic metabolism glycolysis

Anaerobic Metabolism: Glycolysis

  • ONLY carbohydrate can do it.


Anaerobic metabolism glycolysis1

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

Aerobic Metabolism: Krebs Cycle and Electron Transport System (ETS)

  • Can metabolize fat, carbohydrate (finish the job) and some protein.


Human energy systems

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

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

Fuel sources used during exercise Depend on:

  • Intensity of activity

  • Duration of activity

  • Fitness level of the individual

  • Macronutrient and kcalorie content of diet


Human energy systems

  • 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

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 on1

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

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)


Human energy systems

  • 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).


Human energy systems

  • 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 on2

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 duration

Exercise Duration

FAT

CHO

rest

TIME


Fuel sources used during exercise depend on3

Fuel sources used during exercise Depend on:

  • Intensity of activity

  • Duration of activity

  • Fitness level of the individual

  • Macronutrient and kcalorie content of diet


Fitness status

Fitness Status

  • Increased fitness status:

  • Increased:


Human energy systems

  • Training Effects of Aerobic Exercise:

    •  LDL (“bad”)cholesterol,  HDL (“good”)cholesterol

    • strengthened heart, lungs

    • curbed appetite

    •  metabolic rate…


Human energy systems

  • 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 on4

Fuel sources used during exercise Depend on:

  • Intensity of activity

  • Duration of activity

  • Fitness level of the individual

  • Macronutrient and kcalorie content of diet


Human energy systems

Diet

  • High fat diet

  • Lower fat, mod. prot, high CHO diet


Fatigue

Fatigue

  • The inability to continue exercising at a desired level of intensity

  • Inability to produce ATP to meet demands

  • Other factors

  • We’ll address fatigue in later sections.


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