Download Energy Systems

Energy Metabolism
  Energy
Energy Transfer
in the Body
Refer to text for more detail.
 
  Metabolism
 
Biologic Work in Humans
  Mechanical
the capacity or ability to perform work.
Energy is required for muscle
contraction and other biological work
such as digestion, nerve conduction,
secretion of glands, etc.
the sum total of all chemical reactions
occurring in the body.
Adenosine Triphosphate (ATP)
Work
  Transport
Work
  Chemical
Work
Nitrogen
Phosphorous
Carbon
Oxygen
The most common immediate energy currency
of the cell (the all purpose nucleotide)
Metabolic Production of ATP
 
Energy
Aerobic Processes
processes which
require the presence
of oxygen delivered
by the blood
Adenosine Triphosphate
Nitrogen
Phosphorous
+Pi
Adenosine Diphosphate
Carbon
Oxygen
1
ATP-CP (Phosphagen) System
All-out power for approximately
10 seconds
Biologic Work
ATP !##
#" ADP + Pi +
ATPase
CP !##
#" C + Pi +
Creatine
Energy
Energy
Kinase
Principle of Coupled Reactions
Anaerobic Glycolysis
The Glycolytic System
Glucose
Net production of
2 or 3 ATP molecules
10 chemical reactions
2 Pyruvate
Lactate
Glucose
  Glucose
can be made available in the
muscle cells for breakdown to lactate
principally by two methods:
 
 
Lactate
glucose molecules may pass from the
blood through the muscle cell membrane
into the cell interior (net 2 ATP), or
the glucose can be split from glycogen
stores in the muscle cell itself (net 3 ATP).
  Glycogen
is stored in liver and muscle
tissue.
Anaerobic Glycolysis
 
 
 
 
Anaerobic glycolysis can produce ATP rapidly to
help meet ATP requirements during severe
exercise when oxygen demand is greater than
oxygen supply
High rates of ATP production by glycolysis
cannot be sustained for very long (40-60 sec.)
Low muscle pH is associated with hydrogen ion
concentration and lactate formation
High acidity is believed to contributes to the
acute muscular discomfort experienced during
intense exercise.
Predominates in all-out efforts
30-90 seconds
50-200 meters
2
Aerobic Processes
Aerobic Carbohydrate Breakdown
Pyruvic Acid
Acetyl Coenzyme A
Krebs Cycle
Wall of
Mitochondria
Anaerobic Conditions
No O2 available
Pyruvate
not worry about specific yields of ATP.
on whether glycogen or
glucose is used and depending on which
shuttle system is used to transport NADH
molecules to the mitochondria you can
get yields of 36 to 40 ATP.
  The main thing is to see the approximate
increase in ATP yield between anaerobic
breakdown (2 or 3 ATP) versus aerobic
breakdown (36-40 ATP)
  Depending
Glucose
Glycolysis (2 ATP)
Aerobic Conditions
ATP Yield
  Do
Lactate
Glycolysis (2 ATP)
Pyruvate
Electron
Transport
Chain
O2 available
Krebs cycle
Electron TC
36 ATP
+CO2
+H2O
Total ≈ 38 ATP
Predominates in the majority of daily activities and
lower intensity, long-duration sports.
An all-out effort of 2 minutes is approximately
50% aerobic and 50% anaerobic
Aerobic Breakdown of a
Glycogen Molecule
Glycogen
Glucose
Pyruvate
Acetyl - CoA
Kreb's cycle Electron Transport C + O2
CO2 + H2O + ATP
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Energy Release From Fat
  The
actual fuel reserves from stored fat
represent approximately 80,000 to
100,000 kcal of energy in an average
size male or female.
  In contrast, the carbohydrate energy
reserve is less than 2,000 kcal, of which
1,500 kcal are stored as muscle
glycogen, 400 kcal as liver glycogen, and
about 80 kcal of glucose are in the blood.
Energy Release From Protein
  Research
findings indicate that protein
breakdown above the resting level occurs
during exercise of long duration when
carbohydrate stores become low.
  It
has been suggested as much as 15%
of the energy during strenuous long
duration exercise can come from protein.
% phosphagen % glycolytic
anaerobic
anaerobic
5 seconds
10 seconds
30 seconds
60 seconds
2 minutes
4 minutes
10 minutes
30 minutes
60 minutes
120 minutes
85
50
15
8
4
2
1
Negligible
Negligible
Negligible
10
35
65
62
46
28
9
5
2
1
%
aerobic
5
15
20
30
50
70
90
95
98
99
Aerobic Breakdown of
Fatty Acids
Less efficient
than carbohydrate
Fat
in terms of energy
Fatty acids
per O2 used
Beta oxidation
Acetyl-CoA
Kreb's cycle Electron Transport C + O2
CO2 + H2O + ATP
Aerobic Breakdown
of Proteins
Protein"
Amino acids
Deamination Kreb's cycle Electron Transport Chain + O2
CO2 + H2O + ATP
Relative contribution of aerobic and
anaerobic energy during maximal physical
activity of various durations.
Duration of Maximal Exercise
Seconds
% anaerobic
% aerobic
Minutes
10
30
60
2
4
10
30
60
90
80
70
50
35
15
5
2
120
1
10
20
30
50
65
85
95
98
99
4
Phosphagen Energy Production
Continuum
Figure 6.5 in text
The text graph shows this
on logarithmic scale
Lactic
Lactate
% Max
Power
Aerobic
ATP-Creatine Phosphate System
ATP !##
#" ADP + Pi +
ATPase
CP !##
#" C + Pi +
Creatine
Kinase
General Characteristics of
the Three Energy Systems
Energy
Energy
For a max 1 second effort you do not
really need to resynthesize much ATP –
you have enough in the muscle already
Table 6.3: Estimated Maximal Power Output
and Capacity of the Three Energy Systems
Energy System
Power
Moles
ATP per
minute
Capacity
Total moles
of ATP
available
ATP-PC (phosphagen)
Glycolytic
Aerobic System
3.6
1.6
1.0
0.7
1.2
90.0
Aerobic Power ≈ 28% of Peak Phosphagen System Power
Capacity and Power of the
Three Energy Systems
(Untrained Male Subjects)
Energy System
Phosphagen (ATP/PC)
Anaerobic gylcolysis
Aerobic (oxidative)
ATP Production
Capacity
Power
(total moles)
(moles/min)
0.6
1.2
Theoretically Unlimited
3.6
1.6
1.0
Glycolytic System power ≈ 44% Peak Phosphagen Power
(Some researchers report this value to be higher ≈ 60%)
5
Rankings of Rate and
Capacity of ATP Production
System
ATP-PC
(phosphagen)
Anaerobic glycolysis
Oxidation of
carbohydrates
Oxidation of fats
and proteins
Human Power Output
Power
Capacity
rate of ATP
production
1
capacity of ATP
production
4
2
3
3
2
4
1
(energy systems)
Graph from “Champion Athletes”
Wilkie 1960
Time Motion Studies
Energy Transfer
in Exercise
The energy systems previously
discussed are related to all human
activity. We now need to relate this
information specifically to exercise.
English 1st Division (Premier) Players
Position and Distance Covered (in meters)
Activity Mid-field Full-back Striker Centre-back Average
Jog
4042
2907
2769
2908
3157
Cruise
2159
1588
1752
1596
1774
Sprint
1063
787
1068
829
937
Walk
2034
2293
2310
1774
2103
Back
507
670
498
652
582
Total
9805
8245
8397
7759
8552
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Ajax Amsterdam Data
Soccer Activity
Walk
Percentage of Total
Match Time
20-30%
Jog
30-40%
Run
15-25%
Sprint
10-15% (18%)
Backwards
4-8%
4s
ATP
ATP-CP
10s
30s
3 min +
10 seconds
30 seconds
60 seconds
2 minutes
4 minutes
10 minutes
30 minutes
60 minutes
120 minutes
Anaerobic
ATP (in muscles)
Anaerobic
ATP + PC + Some muscle
glycogen
4-20 seconds
(ATP-PC/Glycolytic)
Anaerobic
Anaerobic
(Glycolytic)
Muscle glycogen
120-240 secs
Aerobic +
Glycolytic
Muscle glycogen
+ a little from other fuels
>240 secs
Aerobic
Muscle glycogen + Fatty
Acids + Protein
Performance Intensity Major Energy
Time
of Event
System(s)
Anaerobic Power
Endurance
10
35
65
62
46
28
9
5
2
1
%
aerobic
5
15
20
30
50
70
90
95
98
99
Types of Activity
0-6 seconds
Very
Intense
ATP-CP
Jumping, throwing, kicking,
50 metre sprints, base-running
6-30
seconds
Intense
ATP-PC and
Glycolytic
100-200 metre sprints
Glycolytic
600-800 metres run, ice
hockey shifts, box lacrosse
shifts, 100-metre swim
2-3 minutes
Moderate
Glycolytic
and oxidative
800-100 metre runs
>3 minutes
Light
Oxidative
systems
Running > 1000 metres,
distance cycling, cross country
skiing, swimming > 200-m
Aerobic endurance
85
50
15
8
4
2
1
Negligible
Negligible
Negligible
ATP + PC + Muscle
glycogen
45-120 secs
30 seconds– Heavy
2 minutes
% phosphagen % glycolytic
anaerobic
anaerobic
5 seconds
1-4 seconds
Five Areas of the Energy Continuum
Sustained Power
Oxygen
Predominate Energy
Supplied By
(Glycolytic/ATP-PC)
Strength Power
ATP-CP + glycolytic
Classification
20-45 secs
Predominant Energy Pathways
0s
Duration
Primary Metabolic Demand From
Sports or Activity
Phosphagen
System
Anaerobic
Glycolysis
Aerobic
Metabolism
Baseball
High
Low
-
Basketball
High
Moderate to High
-
Field Events
High
-
-
Field Hockey
High
Moderate
Moderate
Football (American)
High
Moderate
Low
Ice Hockey
High
Moderate
Moderate
Lacrosse
High
Moderate
Moderate
Marathon (42 km)
Low
Low
High
Soccer
High
Moderate
Moderate
Tennis
High
Moderate
-
Volleyball
High
Moderate
-
Wrestling
High
High
Moderate
Weight Lifting
High
Low
Low
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Average VO2 max (ml/kg.min) for
Non-Athletes and Athletes
Average VO2 max (ml/kg.min) for
Non-Athletes and Athletes
From
Chapter
5 – you
shouldMale
see a high
Group
or Sport
Age
Female
positive
correlation
between
a
sport 38-46
with
Non-athletes
10-19
47-56
a high demand on the
oxidative
system
20-29
43-52
33-42
and the athletes VO260-69
max. 31-38
22-30
Baseball
Cycling
Football
Gymnastics
Ice Hockey
Rowing
18-32
18-26
20-36
18-22
10-30
20-35
48-56
62-74
42-60
52-58
50-63
60-72
47-57
36-50
58-65
Oxygen Deficit
Group or Sport
Age
Male
Female
Skiing – Alpine
18-30
57-68
50-55
Skiing –
Cross-country
20-28
65-95
60-75
Soccer
22-28
54-64
-
Speed Skating
18-24
56-73
44-55
Swimming
10-25
50-70
40-60
Weight Lifting
20-30
38-52
-
Wrestling
20-30
52-65
Oxygen Debt
O2 Deficit
O2 Deficit
Steady State
O2 consumption
VO2
(l/min)
VO2
Rest
Time
Resting
VO2
Oxygen Debt after
Anaerobic Exercise
O2 Deficit
O2 Debt
Exercise
“Rapid” portion
of debt
O2 Debt
O2 Debt
Exercise
TIME
Recovery
Recovery
Oxygen Debt
O2 Deficit
VO2 max
TIME
Exercise
TIME
“Slow” portion
of debt
Recovery
8
Figure 6.11 Lactate threshold and
the onset of blood lactate (OBLA)
Recommended Recovery Times after
Exhaustive Exercise
Recommended Recovery Time
Recovery Process
Minimum
Maximum
Restoration of ATP & CP
2 min
3 min
Repayment of alactate O2 debt
3 min
5 min
Restoration of O2-myoglobin
1 min
2 min
Restoration of muscle glycogen 10 hr
46 hr (prolonged)
5 hr
24 hr (intermittent)
Removal of lactate from
30 min
1 hr (exercise-rec)
muscle and blood
1 hr
2 hr (rest-recover)
Repayment of lactate O2 debt
30 min
1 hr
Lactate does not cause muscle soreness
 
 
Despite the commonly
held belief that lactic
acid (lactate) causes
muscle soreness this
has been discredited.
Delayed onset muscle
soreness is likely
caused by damage to
muscle fibers and
associated connective
tissue.
Ice Hockey Post-Game Recovery
 
A light bike ride before/after exercise is a great
way to warm-up or cool down along with
stretching. Also, riding after a game helps to
"flush out" lactic acid and other waste your
muscles produce during activity; A cool-down
flush ride should last around 10-min (often up to
30-min); Get your heart rate up around 140 bpm
(Level II) for 5 min, then back off to a easy spin
(Level I); You don't want to go hard enough to
produce any more lactic acid (lactate); Stretch!!!
 
This quote from” Paul Goldberg, of the Colorado
Avalanche, February 1st, 2006.
Blood Markers
 
 
Getting a ball in
the face also
causes soreness!
If we take a blood sample from a runner the day
after a marathon, especially an ultra-marathon,
we find that the levels of an enzyme called
creatine kinase are very high. This is a marker
of muscle damage as this particular enzyme
"leaks" from damaged muscle.
The "damage" is in the form of minute tears or
ruptures of the muscle fibres. We can see this
trauma to the muscle if a sample of muscle is
examined microscopically.
9
Blood Markers (cont.)
 
 
However, it is not just the muscle that is
damaged. By measuring hydroxyproline, it is
possible to show that the connective tissue in
and around the muscles is also disrupted.
What this shows is that stiffness results from
muscle damage and breakdown of connective
tissue.
Muscle Fatigue and Lactate
 
 
 
 
Lactic acid does not actually exist as an acid in
the body but rather as “lactate.
Producing lactate is a beneficial process since it
allows the regeneration of a coenzyme that
ensures that energy production is maintained
and exercise can continue (see text).
Lactate also does not cause an increase in
acidity (acidosis) within the muscle.
When ATP is broken down to release energy for
muscular contraction a hydrogen ion is released.
This increases acidosis.
Muscle Fatigue & Calcium Channels
 
 
Leaked calcium also stimulates an enzyme that
attacks muscle fibers and also leads to fatigue
and possible damage.
However, as very high
acidity could also cause
damage to the cells the
calcium leaks may be a
protective mechanism to
prevent muscle cell
damage due to excessive
acidity.
Stretching and DOMS
 
 
There is no statistically strong evidence that
stretching reduces post exercise muscle
soreness.
Intense stretching can cause muscle soreness.
Muscle Fatigue and Hydrogen Ions
 
 
 
 
ATP-derived hydrogen ions are primarily
responsible for increases in acidity in the muscle.
High acidity is one factor that contributes to acute
muscular discomfort experienced during and
shortly after intense exercise.
However, recent evidence suggests fatigue is
caused by calcium leaking into muscle cells from
release channels within the muscle.
Calcium helps control muscle contractions but
after extended high-intensity exercise, channels in
the muscle cells begin to leak calcium, which
leads to weakened muscle contractions.
Neural Fatigue
  There
is also the issue of Central Nervous
System (CNS) fatigue.
  During intense repeated bouts of
strenuous exercise neurotransmitters get
depleted and reduces physical and
cognitive performance.
  Central and peripheral fatigue factors are
discussed in text Chapter 6.
10