Download VCE PE Unit 3: Preparing Students for the End of Year Exam

PSE 4U
Section 5
Energy Systems
Wayne Judge Sept 2009
Characteristics and Interplay of
Energy Systems for Physical Activity
• On completion of this topic you should be able to:
• Demonstrate knowledge of the characteristics
and interplay of energy systems for physical
activity and recovery in relation to duration,
intensity and type of activity.
• Describe the interplay of the energy systems
using correct terminology
• Analyse the relationship between energy systems
and physical activity
Sept 2009
ATP - Adenosine Triphosphate
• Energy for muscular contraction comes from
the breakdown of ATP - adenosine
triphosphate.
• ATP is a chemical compound which consists
of one complex group, adenosine, and 3
less complex parts called phosphate groups
Adenosine
P
Sept 2009
P
P
Energy From ATP
• The bonds between the phosphate groups
are high energy bonds.
• When one of these bonds is broken energy
is released, and ADP (adenosine
diphosphate) and inorganic phosphate
(Pi) are formed.
• The energy released during this breakdown
represents the energy used for muscular
contraction.
Sept 2009
The Breakdown of ATP
High energy
bonds
Adenosine
P
P
P
Energy
Pi
Sept 2009
ATP – Storage Within Muscles
• ATP requirement of a 70kg adult male –
190 kg per 24 hour period
Required ATP
Store
Actual ATP
Store
190 kg
50 g
Sept 2009
ATP Storage Within Muscles
PROBLEM:
• There is not enough ATP within our
muscles to last for even a few seconds.
SOLUTION:
• Find ways to replenish our muscular stores
of ATP
Sept 2009
Production of ATP
• Supply of ATP to muscles is dependant upon the
resynthesis of ATP from ADP and Pi.
• The energy for the resynthesis of ATP is
obtained via the three energy pathways or
systems.
Sept 2009
The Three Energy Pathways
(Systems)
ENERGY SYSTEMS
Anaerobic
ATP-PC System
Aerobic
Anaerobic Glycolysis
Sept 2009
Aerobic or
Oxygen System
The Three Energy Pathways
• All three energy systems contribute to the
resynthesis of ATP under exercise conditions.
• However, which energy system/s is predominate
depends upon the ATP demand of the activity.
• Two factors determine ATP demand:
• Exercise duration – how long the activity lasts for
• Exercise intensity – how hard the exercise is
performed at
• Generally speaking, as exercise duration increases
the intensity at which it can be performed decreases
Sept 2009
Anaerobic Pathways
• Anaerobic pathways can supply energy for
ATP resynthesis very quickly.
• They are the major energy systems utilised
during high intensity exercise since muscles
need a rapid but brief supply of ATP
during such activities.
Sept 2009
Aerobic Pathways
• The aerobic energy pathway supplies energy for
ATP resynthesis at a much slower rate than the
anaerobic pathways.
• This system is the predominate supplier of ATP
during endurance events:
• Slower rate of use
• Greater total use
Sept 2009
The ATP-PC
System
Wayne Judge Sept 2009
The ATP-PC System
• Least complicated of the three energy systems
• Produces energy for ATP resynthesis most
rapidly.
• Relies upon muscular stores of ATP and
another chemical compound called
phosphocreatine.
P
CREATINE
Sept 2009
Phosphocreatine
• Phosphocreatine (PC), like ATP, is stored in
limited quantities in muscles.
• Phosphocreatine is also like ATP in that when its
phosphate group is removed a large amount of
energy is released.
• This energy is used to resynthesise ATP from ADP
and Pi.
CREATINE
P
CREATINE
Sept 2009
+ ENERGY +
P
The ATP-PC System
Phosphocreatine
ATP
Energy
Energy
Creatine
ADP + Pi
Sept 2009
For
Muscular
Contraction
The ATP-PC System
• PC stores depleted within 5 - 15 seconds of high
intensity exercise
• Peak energy production from ATP-PC system
occurs after approximately 7 – 8 seconds of
maximal intensity activity.
• Therefore, this system:
• Provide only a very limited amount of energy for
ATP resynthesis
• But is able to supply this energy very rapidly.
Sept 2009
The ATP-PC System
• IN 30 Seconds,
List as many sports/events as possible that would
primarily use this energy system.
The ATP-PC System
and Exercise
• This system is the predominant energy
system during high-intensity activities:
• e.g sprints, throws and jumps
• e.g activities that take approximately 5
– 10 seconds to perform.
Sept 2009
Textbook Reading
• Read pages 81 – 83.
The Anaerobic
Glycolysis (Lactic Acid)
System
Wayne Judge Sept 2009
Anaerobic Glycolysis System
• Involves muscular stores of glycogen being
converted into glucose and then, with the
aid of enzymes, this glucose is converted into
a substance called pyruvate.
• when there is a shortage of oxygen,
pyruvate becomes lactic acid. OUCH!!
• During this series of reactions, energy is
released to resynthesise ATP from ADP and
Pi.
Wayne Judge Sept 2009
Anaerobic Glycolysis System
Glycogen
ATP
Glucose
Energy
Energy
Pyruvate
ADP + Pi
Insufficient
Oxygen
Lactic
Acid
Pyruvate
sufficient
Oxygen
Wayne Judge Sept 2009
For
Muscular
Contraction
Anaerobic Glycolysis
• This system is also activated at the
beginning of high intensity exercise.
• Predominant contributor of energy for
10 seconds to 2-3 minutes during highintensity exercise bouts.
Sept 2009
The Aerobic or
Oxygen System
Wayne Judge Sept 2009
The Aerobic System
• Slowest system to contribute towards ATP
resynthesis (takes time for HR and breathing to
adjust).
• However, capable of producing the most energy
when comparing all three energy systems.
• predominate contributor to energy production
during continuous sub-maximal exercise which
exceeds 2 minutes
Sept 2009
The Aerobic System
• At rest - fats used predominately (⅔’s) and about ⅓
from carbohydrates.
• enough glycogen (stored glucose) for about 2
hours of prolonged sub-maximal exercise.
• If you run out of stored glycogen (carbs)  called
HITTING the WALL
• Fat metabolism requires far more oxygen than
compared to carbohydrates.
Sept 2009
Aerobic Energy Production
from Carbohydrates
• Glycogen is broken down to pyruvic
acid and during this process energy is
released for ATP resynthesis.
• In the presence of sufficient oxygen,
pyruvic acid enters mitochondria for
aerobic energy production
Sept 2009
Aerobic Energy Production
from Carbohydrates
• The end products of this process are carbon
dioxide (CO2) and water (H2O)
Sept 2009
Aerobic System:
Carbohydrate Metabolism
Stage 1
Glycogen
ATP
Glucose
Energy
Energy
Acetyl
coenzyme A
+ oxygen
ADP + Pi
Stage 2
Krebs
Cycle
Stage 3
Energy
ET
Chain
Energy
ATP
For Muscular
Contraction
Energy
ADP + Pi
ATP Production Under
Exercise Conditions
• For activities of high intensity and short
duration:
• Anaerobic pathways supply the great majority of the
energy required.
• Activities of a prolonged sub-maximal or lowintensity nature:
• Aerobic system supplies the bulk of the required energy
once the respiratory and circulatory systems have
adapted to meet the muscles demand for extra oxygen
for the aerobic resynthesis of ATP.
Sept 2009
Energy Systems Interplay
• Most activities rely on a combination or interplay
of the energy systems, with all three energy systems
contributing to the total energy supply.
• Body does not suddenly switch from one energy
system to another.
• Transition - one energy system is increasing its
contribution while another, is decreasing its
relative contribution.
• This can be best illustrated by considering what
happens when we undertake a high intensity
activity.
Sept 2009
Energy System Contributions
to High Intensity Exercise
• Aerobic System:
• If the exercise continues beyond about 45
seconds, the intensity must decrease in
order for it to be continued.
• If the exercise continues for 1-2 minutes
or longer the aerobic system will become
the predominant energy supplier.
• This can be shown on the following graph:
Sept 2009
Wayne Judge Sept 2009
Energy System Contributions
During High Intensity Activity
• ATP-PC system:
• Predominant energy system during the first 5 10 seconds.
• Anaerobic glycolysis system:
• If the exercise continues beyond 15 seconds
this system will begin to assume predominance.
• It will be the predominant energy supplier for
high intensity activities of 30 – 60 seconds
duration.
Sept 2009
Wayne Judge Sept 2009
Textbook Reading
• Read pages 84 – 85
• Add Table 5.1 on page 86 to your notes