What Is Energy Balance and Why Is It Important? Energy balance
is achieved when the kilocalories consumed equal the kilocalories
expended
Slide 5
Foods and their conversion to energy Food is consumed =chemical
energy converted into mechanical energy (muscular contractions
& movement) Carbohydrates, fats and protein are the only
sources of food energy and fuel.
Slide 6
Energy (ATP) is stored in small amounts, therefore the rest is
stored as: Glucose = Glycogen (muscle & liver) Fatty Acids =
Body fat Amino Acids = Growth, repair or excreted as waste
Slide 7
Carbohydrates Sugars and starches = bodys preferred source of
fuel esp. during exercise. Carbohydrates = primary energy source
during anaerobic exercise of high intensity and short duration.
Carbohydrates are broken down and stored as glucose in the blood
and glycogen in the muscles and liver. Excess carbs are stored
around the body as adipose tissue (fat tissue)
Slide 8
7 CARBOHYDRATE SOURCES Carbohydrates come in two sources:
Simple sugar glucose Storage form of glucose glycogen Glycogen is
stored in Muscles Liver Blood (smallest % in blood) Liver = only
tissue that can release stored glycogen in the form of glucose
Liver = maintain blood sugar levels by releasing glucose through
gluconeogenesis & glycogenolysis
Slide 9
Carbohydrates All carbohydrate converted to glucose Primary ATP
substrate for muscles, brain Glycogen converted back to glucose
when needed to make more ATP Glycogen stores limited (2,500 kcal) =
must rely on dietary carbohydrate to replenish
Slide 10
Energy from Carbohydrates Glucose is absorbed from the
intestines into the blood and broken down by glycolysis Excess
glucose intake stimulates storage as glycogen and fatty acids
Slide 11
Energy Release From Carbs Carbs primary function to supply
energy for cellular work Carbs = only macronutrient whose stored
energy generates ATP anaerobically NB for maximal exercise that
requires rapid energy release intramuscular glycogen stores
supplies most of the energy for ATP resynthesis
Slide 12
Energy Release From Carbs During light & moderate aerobic
exercise carbs supply 1 / 3 of bodys energy requirements Breakdown
of carbs for energy supply occurs more rapidly than breakdown of
fats. = depletes glycogen reserves significantly = reduces exercise
power output Prolonged exercise (marathon runners) = muscle &
liver glycogen depletion
Slide 13
Energy from Carbs and Physical Activity Carbs provide QUICK
ENERGY. They supply energy for both AEROBIC & ANAEROBIC
physical activity Used for physical activity of a comparatively
SHORT length of time and HIGH INTENSITY
Slide 14
Fats Fats = butter, oils, nuts. Fat = bodys preferred source of
fuel at rest. More oxygen is required by the body to use fat as a
fuel than to use carbs to produce ATP.
Slide 15
14 FAT SOURCES Fat for fuel is in the form of free fatty acids
Two sources of these fats are: Peripheral fat stores Rolls of fat
on the stomach, glutes Intramuscular fat Triglyceride stored in the
actual muscle
Slide 16
Most Body Fat Is Stored in Adipose Tissue Two types of fat make
up total body fat: Essential fat Found in bone marrow, heart,
lungs, liver, spleen, kidneys, intestines, muscles, and central
nervous system Women have 4x more essential fat than men Stored fat
Found in adipose tissue Subcutaneous fat located under the skin
Visceral fat stored around the organs in the abdominal area
Slide 17
Fats Fats have the capacity to produce much more ATP than carbs
BUT: the conversion rate is much less efficient require much more
oxygen to produce the same amount of ATP. Fatty acids are stored in
the blood, triglycerides in the muscles Excess fats are stored as
adipose tissue around the body
Slide 18
Energy from Fats The body stores most fats as triglycerides
When blood glucose falls, enzymes break triglycerides into glycerol
and fatty acids Glycerol enters the energy cycles to be converted
to glucose Fatty acids yield more energy (ATP) than carbs
Slide 19
Fat Efficient substrate, efficient storage +70,000 kcal stored
in body Energy substrate for prolonged, less intense exercise High
ATP yield but slow ATP production Must be broken down into free
fatty acids (FFAs) and glycerol Only FFAs are used to make ATP
Slide 20
Fat release for energy and physical activity Fats provide SLOW
ENERGY The energy release from fats is too slow to be used when
used when working hard Used for walking and low-impact exercise
Used for exercise of a longer duration, and MODERATE INTENSITY
Physical activity of LONG DURATION and HIGHER INTENSITY is fuelled
more from fat stores in the body because the glycogen store becomes
depleted
Slide 21
Protein Protein includes meat, fish, poultry, dairy, eggs &
lentils. Protein is used for growth & repair of the body &
as fuel source in extreme situations. Body only uses protein as
energy source when glycogen & fat sources have already been
depleted. ie. marathon or starvation
Slide 22
Energy from Proteins Proteins enter the bloodstream as amino
acids Amino acids can be used for energy by removing the amino
group (as ammonia)
Slide 23
Energy release from Protein Energy yield not easy to determine
Nitrogen presence unique Nitrogen excretion requires ATP
expenditure Generally minimal, estimates therefore ignore protein
metabolism
Slide 24
23 Fuel Utilization is Determined by Energy Output or Intensity
Level First thing in the morning before you eat breakfast = energy
demands are very low can be met mainly by fat derived from blood
free fatty acids Free fatty acids are released at a low rate by
peripheral fat stores This allows the muscles to preserve both
intramuscular fat and glycogen stores
Slide 25
24 Exercise Intensity and Duration For all energy substrates,
carbs and fats, ultimately ATP is generated in the muscle cell as
the high energy substrate for moving muscle. Carbs can also be
broken down in the absence of oxygen for limited energy
production
Slide 26
25 Fuel Utilization - Intensity Low intensity Walking: energy
output can be generated entirely by peripheral fat stores releasing
free fatty acids Stimulus to increase FFA release to maintain
enough blood concentrations of FFA for uptake by the working
muscles
Slide 27
26 Moderate Intensity Exceeds the capacity of peripheral fat
stores to supply enough free fatty acids to meet energy output
rates= Intramuscular triglycerides are broken down to provide more
fat sources Peripheral fat uptake does not stop it plateaus +
another source is provided to makeup the needed
energy(glucose/glycogen)
Slide 28
27 Medium/ Moderate Intensity A medium intensity pace can be
maintained until either your intramuscular fat stores are depleted
or you run out of glycogen When the glycogen is depleted then
protein is broken down for energy
Slide 29
28 High Intensity High Intensity exercise goes above the limits
of energy production rates that fats can supply and requires
additional energy derived from glucose glucose requires less oxygen
per unit of energy At lower intensities, the energy production rate
is low enough that oxygen is plentiful enough for fat burning
Slide 30
29 Very High Intensity At very high intensities the aerobic
system reaches its limitations for energy generation (fat or
glucose) The anaerobic system takes over Only a little of the
potential energy of glucose is released but is done so in a very
rapid manner to meet short duration and very high energy production
rates
Slide 31
30 The Benefits of Exercise At Any Intensity Low intensity
exercise is not the is not the best form for weight loss
Intramuscular stores (fat or glycogen) are depleted During the
recovery phase (post exercise) fats and carbs from the diet will go
to restoring those levels High intensity exercise can lead to fat
loss depletion of glycogen & glycogen stores must be
replenished with dietary carbs that would otherwise be burned for
energy While the storage process occurs = the body will burn extra
fat to supply current energy needs