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# Human Energy Systems PowerPoint PPT Presentation

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:

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:

• 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:

• Rough estimate: Body weight in pounds X 10

• More accurate:

Men:

Women:

Example:

### Energy to Support Physical Activity

• TEE = Thermic Effect of Exercise

### Energy Needed to Process Food

• TEF = Thermic Effect of Food

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...

• But within our individual range…

• lowest would be achieved via

• highest would be achieved with

## Fueling Activity

• 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:

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:

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:

### Metabolic Pathways

• Take place in the cytosol and mitochondria of the cell

• Anabolic Pathways:

• Catabolic Pathways:

• Anaerobic:

• Aerobic:

## Overview of Pathways

### Anaerobic Metabolism: Glycolysis

• ONLY carbohydrate can do it.

### 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

FAT

CHO

rest

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

### Fitness Status

• Increased fitness status:

• Increased:

• 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

### Diet

• High fat diet

• Lower fat, mod. prot, high CHO diet

### 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.