• Energy in the human body come from the
breakdown of nutrients like carbohydrates,
proteins and fats
Food = Energy (ATP)
• The end result of this breakdown is the
production energy in the form of Adenosine
triphosphate (ATP)
• ATP provides energy necessary for body
function.
• Because the body can not easily store ATP it is
necessary to continually create ATP during
exercise.
• In general, the two major ways the body converts
nutrients to energy are:
• Aerobic metabolism (with oxygen)
• Anaerobic metabolism (without oxygen)
• There is a total of 3 Energy systems that interplay
to supply the fuel needed for exercise, with the
intensity and duration of the exercise
determining which method gets used when.
• The 3 energy systems are:
1) ATP-PC System (Anaerobic without oxygen)
2) Anaerobic Glycolysis (Anaerobic without oxygen)
3) Aerobic (Aerobic with oxygen)
• The ATP-CP energy pathway (sometimes called the phosphate
system) uses ATP CP stores directly.
• This pathway doesn't require any oxygen to create ATP.
• When is it used? supplies about 10 seconds worth of energy and is
used for short bursts of exercise such as a 100 meter sprint.
• It first uses up any ATP stored in the muscle (about 2-3 seconds
worth) and then it uses creatine phosphate (CP) to resynthesize ATP
until the CP runs out (another 6-8 seconds).
• After the ATP and CP are used the body will move on to either
aerobic or anaerobic metabolism (glycolysis) to continue to create
ATP to fuel exercise.
• ATP  ADP + “energy” (2-3 secs)
• ADP + CP  ATP + C (4-10 secs)
Primary Energy Source
Stored ATP, CP
Duration of Activity
Up to 10 sec
Sporting Events
Weight lifting, high jump, long jump,
100m run, 25m swim
Advantages
Produce very large amount of energy in a
short amount of time
Limiting Factors
Initial concentration of high energy
phosphates (ATP, PC)
• To test the ATP-CP system we use muscular
power.
• Bicep Curl 1RM (repetition maximum)
• The anaerobic energy pathway, or glycolysis, creates ATP exclusively
from carbohydrates
• Creates this ATP without the need of oxygen
•
Lactic acid and Hydrogen ions are by-product of this system.
• When is it used? Anaerobic glycolysis produces energy for short,
high- intensity bursts of activity lasting no more than several
minutes before the lactic acid build-up reaches a threshold known
as the lactate threshold and muscle pain, burning and fatigue make
it difficult to maintain such intensity.
Primary Energy Source
Stored glycogen, blood glucose
Duration of Activity
10 secs – 2 min
Sportng Events
200m swim, 400 min sprint, Fast break in
basketball etc.
Advantages
Ability to produce energy under
conditions of inadequate oxygen
Limiting Factors
Lactic acid build up, H+ ions build up
(decrease of pH)
Glycogen
Glucose
ADP +
Energy
Pyruvic Acid
(no oxygen)
Lactic Acid
+ hydrogen
ion
ATP
Free
Phosphate
Energy for
Muscles
• Lactic acid threshold is the common term used
when the level of lactate acid nad H+ within the
bloodstream and working muscles is above which
an individual cannot continue to physically
exersise at a desired level.
• Trained athletes can increase their tolerance to
LA accumulation and are able to continue
effective performance or training with much
higher lactate and H+ levels in their working
muscles and circulatory system.
• To test this system in class we use muscle
endurance exercises
• Pushups, Situps, and Lunges for 2 minutes.
• Aerobic system fuels most of the energy needed for long duration activity.
•
It uses oxygen to convert nutrients to ATP.
• This system is a bit slower than the anaerobic.
•
Relies on the circulatory system to transport oxygen to the working
muscles before it creates ATP.
• When is it used? Endurance events, less intense activities, that last long
periods of time.
• This system creates 38 molecules of ATP from 1 molecule of gluscose
Primary Energy Source
Glycogen, Carbohydrates, fats, proteins
Duration of Activity
> 2 min
Sportng Events
Walking, Marathons, triathlons, cross
country skiing, AFL midfielder, Basketball
game, rowing 2000m
Advantages
Large output of energy over a long period
of time, removal of lactic acid
Limiting Factors
Lactate and hydrogen ion accumulation,
overheating, glucose and glycogen stores.
Glycogen
Glucose
ADP +
ATP
Energy
Pyruvic Acid
(no oxygen)
Fats
( and
O2)
+
Protein
(emergen
cy ATP
source)
Citric acid cycle
ATP
for
Muscles
Hydrogen ions
Electron transport
chain
ATP
for
Muscles
Free
Phosphate
Energy for
Muscles
• To test this system we use cardiovascular
endurance
• perform the 12 minute walk run and record
the distance covered in 12 minutes.