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Energy Systems
Nutrition
I. Nutrients: substances needed for growth,
metabolism and bodily functions.
A. Micronutrients:
nutrients required by
humans in small
amounts to
orchestrate a wide
variety of
physiological
functions
• Fiber
• Vitamins
• minerals
B. Macronutrients: nutrients that provide calories
or energy and are required in large amounts.
*Carbohydrates
*Lipids (fats)
*Proteins
*Water
1. Carbohydrates: serve important functions
related to energy metabolism and exercise.
• Synthesized by plants
from water and Carbon
dioxide and sun
• contain C, H and O at a
ratio of 1:2:1 (CH2O)n
*end with “ose”
a. Monosaccharides: bodies
main energy source.
(glucose, fructose,
galactose)
b. Disaccharides: the combination of “two”
monosaccharides (double sugar).
*each disaccharide
contains glucose
Ex. glucose + fructose
=sucrose
*formed by dehydration
synthesis
(condensation
reaction) from the
removal of water.
c. Polysaccharides: three or more sugars
combined.
i. Plant polys:
*Starch- found in seeds,
grains and corn cells
(complex carbs.)
*Fiber- (cellulose) a
non-starch found in
plant cell walls.
ii. Animal Polys: glycogen, formed by
glucogenesis, is stored in mammalian muscle and
liver.
2. Lipids (oils, fats and waxes): consist
primarily as triacylglycerols having a glycerol
and 3 fatty acid chains. Found in adipose
tissue and skeletal muscle.
Lipids Role in the Body
*Energy Reserve
*Thermal insulation
*Transport of fat soluble
vitamins
*Hunger suppressor
a. Saturated vs. Unsaturated Fatty Acids
i. Saturated: contain
only single bonds
between carbon
atoms, all other
bonds attach to
hydrogen.
ii. Unsaturated: contain
one or more double
bonds along the
carbon chain.
3. Proteins: contain carbon, hydrogen,
oxygen and nitrogen.
Proteins Role in the
Body
*tissue synthesis
(anabolism)
*constituents of plasma
membranes
*globular proteins make
up enzymes
a. Amino Acids: the building blocks of proteins
joined by peptide bonds. The body requires 20 diff.
amino acids.
i.
Essential Aminos: 8
aminos that are not
synthesized in the
body and must be
ingested.
ii. Nonessential
Aminos: the
remaining 12
aminos
manufactured by the
body.
II. Recommendations for a Balanced Diet
A. Food Energy Content: is the amount of energy
obtained from food through cellular respiration
Energy Values Per 100
grams of:
• Carbs. = 1600
kilojoules (kJ)
• Lipids = 3700 (kJ)
• Proteins = 1700 (kJ)
*one food calorie equals
about 4.184 (kJ)
Recommended Dietary Intakes
Atheletes
*Carbs. – 500-700g
Non-Athletes
*Carbs. – 300g
*Fats – 65g
Food Pyramid
US suggested dietary
guidelines up through 2008
US suggested dietary
guidelines up through 2011
Current Dietary suggestion
US suggested dietary
guidelines beginning 2012
• Usda =
choosemyplate.gov
•
(not for all; below based on 2000 cal
diet)
•
Fruit Group should provide 4 daily servings, or 2
cups.
•Vegetable Group should provide 5 servings, or 2.5
cups.
•Grain Group should provide 6 ounce-equivalents (1
ounce-equivalent means 1 serving), half of which
should be whole grains.
•Meat and Beans Group should provide 5.5 ounceequivalents or servings.
•Milk Group should provide 3 cups/servings.
•Oils should provide 24g or 6 teaspoons.
•Discretionary Calories: The remaining amount of
calories in each calorie level after nutrient-dense
foods have been chosen. Up to 267 calories could
be consumed in solid fats or added sugars if the
other requirements were been met
•
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WIC
• http://www.floridahealt
h.gov/programs-andservices/wic/_docume
nts/fl-wic-foodseng.pdf
III. Carbohydrate and Fat Metabolism
A. Metabolism: set of
chemical reactions
in living organisms
to maintain life.
1. Catabolism: breaks
down organic
matter.
2. Anabolism: uses
energy to construct
cellular components.
Water
• Essential to all forms of life
– Within cells: medium for vital biochemical
reactions.
– Outside cells: plays a role in:
• Transporting nutrients, waster products, hormones,
respiratory gases
• Thermoregulation, Excretion
• Lubrication of joints, all movement
• Can water be bad for us?
Class Activity
(group consists of 2- 4 people)
• Analyze the nutrition labels provided.
– Choose three labels to evaluate
– ** due at end of period
• Create a one week meal plan for an
athlete of your choice (explain the needs
of the sport, and relationship to nutrients
suggested)
• ** due one week from today
B. The Pancreas: serves as an endocrine and
exocrine gland and regulates blood sugar levels
and aids in digestion.
1. Islets of Langerhans:
clusters of cells
within the pancreas.
a. Beta cells: make up
¾ of the islet cells
and secrete insulin.
b. Alpha cells: secrete
glucagon.
2. The Role of Insulin: increases glucose
uptake by cells. Exercise increases glucose
uptake into skeletal muscle.
a. Glycogenesis:
Insulin activates
enzymes for the
synthesis of
glycogen.
b. Lipogenesis: insulin
inhibits catabolism of
fatty acids to convert
excess glucose into
triacylglycerols.
3. The Breakdown of Glycogen
a. Glycogenolysis:
glucagon and
adrenaline stimulate
the breakdown of
glycogen in the liver
to increase blood
glucose levels during
long periods of
exercise and times of
fasting.
b. Lipolysis: the breakdown (catabolism) of
adipose tissue by glucagon and adrenaline to
increase blood sugar.
Cells
IV. Nutrition and Energy Systems
A. Generalized Animal
Cell:
*ribosomes
*rough ER
*golgi complex
*lysosomes
*nucleus
*mitochondrion
B. Cellular Respiration: the release of
energy from organic compounds in cells.
1. Mitochondria: the
site of cellular
respiration.
Before discussing the various systems by which your body can provide
energy to your muscles, we first need to define what muscle "energy"
actually is. We know that your muscle cells need an energy source to
be able to contract during exercise. At the highest level, the energy
source for muscle contractions is the food you eat. A complex chemical
process within your cells, called cellular respiration, ultimately converts
the energy stored in the foods you eat into a form that is optimized for
use at the cellular level of your muscles. Once food energy has been
converted by cellular respiration it exists at the cellular level in the form
of a molecule called adenosine triphosphate (ATP).
2. Adenosine Triphosphate: (ATP) the
energy currency of the cell.
*the removal of the
outermost
phosphate
releases energy
(7.3 kCal) for
cellular activity.
ATP
ADP
a. Phosphocreatine system: (ATP-CP) resynthesizes ATP by the hydrolysis of
phosphocreatine (PCr).
*phosphate is removed
from PCr and added
to ADP to reform
ATP.
*this occurs at the onset
of intense exercise
without oxygen.
3. Stages of Cellular Respiration:
C6H12O6 + 6O2
6CO2+6H2O+36 ATP
a. Glycolysis:
(anaerobic phase)
*takes place in the
cytoplasm
*glucose is split into two
pyruvates
*yields 4 ATP with a net
gain of 2 ATP
i. Lactic Acid Fermentation: if O2 is deficient
the pyruvates are converted into lactic acid.
*ATP production is
limited, resulting in
muscle fatigue.
b. Aerobic system: in the presence of oxygen
pyruvate is processed within the mitochondria.
i.
Pyruvates combine
with 2 coenzyme A
molecules to form
acetyl-CoA.
ii. Krebs Cycle:
Occurs in the matrix
where acetyl-CoA is
broken down to CO2
and H+. H+ combine
with electron
carriers NAD and
FAD.
iii. Electron transport chain: is used to
transport electrons from NADH and FADH2.
*H+ pumped across the
membrane diffuse back in
to generate 32 ATP
(oxidative
phosphorylation).
*Oxygen acts as the final H+
acceptor to form H2O.
*occurs at a rate of
10,000,000 ATP per/sec
in working muscle cells!
iv. Beta Oxidation: Triacylglycerol is hydrolized to
form fatty acids and glycerol that can be used as
an energy source for cellular respiration.
* glycerol enters
glycolysis to form
pyruvate.
* Fatty acid chains are
transformed into
acetyl-CoA that enter
the Krebs cycle.
* O2 must be present for
this to occur.
Humans have three processes that the body can use to obtain Energy.
The cellular respiration process that converts your food energy into
ATP is in large part dependent on the availability of oxygen.
When you exercise, the supply and demand of oxygen available to your
muscle cells is affected by the duration and intensity of your exercise
and by your cardiorespiratory fitness level.
These energy systems that can be selectively recruited, depending on
how much oxygen is available
The Three Systems
•
Alactic Anaerobic Energy
System
•
This energy system is the first one
recruited for exercise and it is the
dominant source of muscle energy for
high intensity explosive exercise that
lasts for 10 seconds or less
•
It can provide energy immediately, it
does not require any oxygen
(anaerobic), and it does not produce
any lactic acid (alactic).
•
It is also referred to as the ATP-PCr
energy system or the phosphagen
energy system.
•
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Lactic Anaerobic Energy
System
dominant source of muscle energy
for high intensity exercise
activities that last up to
approximately 90 seconds.
this system is dominant when your
alactic anaerobic energy system is
depleted but you continue to
exercise at an intensity that is too
demanding for your aerobic
energy system to handle.
Like the alactic anaerobic energy
system, this system is also
anaerobic and so it does not
require any oxygen.
•
•
•
However, unlike the alactic
anaerobic energy system, this
system is lactic and so it does
produce lactic acid. It is also
referred to as the lactic acid
system or the anaerobic glycolytic
system
The cellular respiration process
consists of a very complex series
of chemical reactions
ultimately converts food energy
(from carbohydrates, fats, and
proteins) into ATP energy. When
oxygen is not available for cellular
respiration, as is the case for the
lactic anaerobic energy system,
lactic acid is produced as a
byproduct.
•
•
Aerobic Energy System
The energy supply at this lower
intensity level, in contrast to the
alactic anaerobic and lactic
anaerobic systems, now becomes
dependent on how efficiently
oxygen can be delivered to, and
processed by, your muscles. A
continuous supply of oxygen
allows you to maintain a reduced
intensity level for a long period of
time.
•
If you are able to extend an
exercise activity beyond
approximately two minutes in
length it will be due to the fact that
you are working at an exercise
intensity level that can be
accommodated by your aerobic
energy system. By five minutes of
exercise duration the aerobic
energy system will have become
your dominant energy source
C. What role does each energy system (ATP-PCr,
glycolytic and aerobic) play during exercise?
1. ATP-PCr: supplies the
immediate energy for
short, explosive
movements. Ex. Sprint,
swinging a bat.
2. Glycolytic: supplies
energy after the initial
10 sec. of exercise.
Used in multiple sprint
sports (soccer, hockey).
3. Aerobic System: supplies long term energy
when exercise extends longer than 2-3 minutes.
D. Oxygen Deficit: diff. between the amt. of O2
consumed during exercise and the amt. that would
have been consumed if aerobic resp. occurred
immediately.
*this reflects the amt. of
energy supplied to
muscles by the
anaerobic systems.
*trained athletes have a
smaller O2 deficit.
E. Oxygen Dept. (EPOC) excess post-exercise
oxygen consumption
*represents the
amt. of O2
consumed in
recovery after
exercise that is
above the resting
level.