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EXERCISE
PHYSIOLOGY
Hazzaa M. AlAl-Hazzaa, Ph D, FACSM
Professor & Director
Exercise Physiology Laboratory
King Saud University
Tel (office): 4678411 (Lab): 4678406
http://faculty.ksu.edu.sa/hazzaa
504 RHS – Spring 2011
KSU
What is Exercise Physiology?
The study of the physiological responses and
adaptation to exercise and training and detraining
at various environmental conditions.
From systemic to sub-cellular level.
During both acute (short term) exercise and chronic
(long term) training.
Involving people of all ages (children to elderly) and
abilities (diseased, healthy and athlete).
Exercise
Bioenergetics
It is the study of the metabolic processes that
can lead to the production and utilization of
energy in forms such as ATP molecules.
KSU
Energy
Energy is the capacity to do work.
It is either potential energy (stored energy) or
kinetic energy (energy of motion).
Forms of Energy:
v Light (sun)
v Mechanical
v Electric
v Nuclear
v Heat (solar)
v Chemical (fuel, oil)
Energy
First Law of Thermodynamics
l
Conservation of Energy – Energy can not
be “Created” or “Destroyed”
l
Our body simply transforms energy
(Chemical) into muscle contraction
(mechanical) and heat.
AdenosineTri Phosphate (ATP)
Ø ATP is the energy currency used for all
processes in the living cells:
l
ATP – Chemical as Potential Energy
l
Phosphate bonds: High Energy
l
Food energy: re-synthesizes more ATP
Immediate Energy for muscle contraction
(ATP) ‫أدﯾﻨﻮﺳﯿﻦ ﺛﻼﺛﻲ اﻟﻔﻮﺳﻔﺎت‬
Adenosine
P
P
Adenosine
P
P
(ADP)
P
+
‫أدﯾﻨﻮﺳﯿﻦ ﺛﻨﺎﺋﻲ اﻟﻔﻮﺳﻔﺎت‬
Pi
+
Energy
Phosphorylation
ATP ←→ ADP + P + ENERGY
CP ←→ C + P + ENERGY
Energy for muscle Contraction
Phosphocreatine
Creatine
ADP
Creatine
+
Energy
P
Pi
P
ATP
Energy for muscle Contraction
‫أدﯾﻨﻮﺳﯿﻦ ﺛﻼﺛﻲ‬
(ATP) ‫اﻟﻔﻮﺳﻔﺎت‬
Breakdown
Synthesis
‫أدﯾﻨﻮﺳﯿﻦ ﺛﻨﺎﺋﻲ‬
(ADP) ‫اﻟﻔﻮﺳﻔﺎت‬
ATP – CP Energy System
Small amount of ATP is stored
l
l
85 g in whole body (about 2 seconds of
muscle contraction)
Must be re-synthesized
CP: quick energy for ATP re-synthesis
l CP stored in larger quantities (enough for
5-6 seconds of muscle contraction)
All out Exercise – 6 to 8 seconds
ATP – CP Energy System
Assuming 20 kg of muscle is used in
exercise, then the Phosphagen energy
system can supply energy for the
working muscle for:
v Walking for one minute
v Jogging for 20-30 sec, or
v Running at maximum speed for 6-8 sec
Bergstrom, et al., In: Muscle metabolism During Exercise, 1971, 422: 539
Hultman, Scand J Clin lab Invest (Suppl), 1967
Anaerobic
Energy
Energy for Muscle Contraction
C + Pi
CP
CHO
Glycogen
breakdown
Anaerobic
Glycolysis
Energy
Cytoplasm
Pyruvic
Acid
ATP
Energy
ADP + Pi
For muscle
CAC
CO22
CO
eETS
Fatty
Acids
Mitochondrion
Aerobic Oxidation
+
H2O
Anaerobic
Glucose
Energy
ATP
H+
Pyruvic Acid (2)
Lactic Acid (2)
Inter Cellular Fluid
Fatty
Acids
Amino
Acids
CO2
CO2 & H+
Mitochondria
Aerobic
Acetyl Co-A (2)
Krebs
Cycle
Energy
H+
ATP
To ETC
Aerobic Glycolysis
Krebs Cycle
l
H+ → Electron Transport Chain
ETC
l
2H+ + Oxygen → H2O + Energy
Glycolysis
KSU
Aerobic Oxidation
Energy
Krebs
Cycle
ATP
CO2
H+
2H+ +
--
O = H2O
Electron
Transport
Chain
ATP
Anaerobic vs Aerobic Energy Systems
Anaerobic
l
l
ATP-CP : ≤ 10 sec.
Anaerobic Glycolysis: < 2 minutes
Aerobic
l
l
l
Krebs cycle (Aerobic glycolysis)
Electron Transport Chain
ß-Oxidation
2 minutes +
How do we relate the
energy systems into
duration and intensity
of exercise?
Maximal Power & Capacity of the Energy Systems
Energy System Maximal Power Maximal Capacity
Immediate
(ATP
ATP--PC
PC))
Short term
(Anaerobic
Glycolysis)
Long term
(Aerobic)
(mole/min)
(Total ATP)
Very High
Very Limited
Somewhat
Somewhat limited
High
Low
Almost Unlimited
Available Energy for Muscles
(based on energy system)
Energy System
Immediate
(ATP
ATP--PC
PC))
Short term
(Anaerobic Glycolysis
Glycolysis))
Maximal power
(w/kg)
Time to
depletion
800
20 sec
325
60 sec
150
60 min
> 6 hours
Long term (Aerobic)
• Aerobic Glycolysis
• FFA Oxidation
Knuttgen, PSM, 2003, 31(3): 35
75
Energy System Contribution (%) during all out
Exercise for 30 sec
50
25
Phosphocreatine
25
Anaerobic Glycolysis
Aerobic Glycolysis
Greenhaff, & Timmons,ESSR,1998, 1-30; Serresse, et al., IJSM, 1988, 9: 456-460
Bicycle Ergometer
Relationship of metabolic power and mechanical
power, based on the energy systems
Knuttgen, PSM, 2003, 31(3): 35
Energy Systems for Exercise
Energy Systems
Immediate: Phosphagen
(Phosphocreatine and ATP)
Short Term: Glycolysis
(Glycogen-Lactic Acid)
Long Term: Aerobic
Mole of
ATP/min
Time to
Fatigue
4
5 to 10 sec
2.5
1.0 to 1.6 min
1
Unlimited
time
Energy Transfer Systems and Exercise
% Capacity of Energy System
100%
Anaerobic
Glycolysis
Aerobic
Energy
System
ATP - CP
10 sec
30 sec
2 min
5 min +
Energy Systems
What happens when we heavily
use anaerobic glycolysis
glycolysis?
?
Lactic Acids concentration in the working
muscles rises
Then we can see its concentration rises in
the blood. But, so What?
The acidity can negatively effect muscle contraction in
2 ways:
1- Interferes with ca++ attachment to Troponin , and
2- Inhibits some of the key enzymes in Glycolysis
Glycolysis..
Lactate is not a Waste Product
Lactate can be used as a Fuel during Exercise
v It can be utilized by slow
twitch muscle fibers (Type I),
through the “lactate shuttle”
Lactate to Pyruvate to Acetyle
Co-A ------ Krebs Cycle
v Used by the heart muscle
v Converted back to glucose
in the liver via the Cori cycle
(Gluconeogenesis)
Cori Cycle
What determines which
path does lactate go
through?
Lactic acid (mMol/L)
Active vs Passive Recovery and Lactate removal
‫اﺳﺘﺮداد ﻏﯿﺮ ﻧﺸﻂ‬
‫اﺳﺘﺮداد ﻧﺸﻂ‬
Time (min)
Costill, et al, JAP, 1977, 43: 695-699
Control of Bioenergetics
ATP-PC System
PC + ADP
Glycogen
C + ATP
1
Glucose
Rate Limiting Enzymes
1. Creatine kinase
2. Phosphofructokinase
3. Isocitrate dehydrogenase
4. Cytochrome oxidase
Glucose 6-phosphate
2
Glycerol
Triglycerides
Phosphoglyceraldehyde
Glycolysis
Pyruvic Acid
Lactic Acid
β-ox
Acetyl CoA
Fatty acids
Ketone
bodies
C4
Krebs
Cycle
3
Amino Acids
C6
Urea
NADH
FADH
C5
Proteins
ETC
4
Why does our body resort
to anaerobic energy system
when it can get more ATP
from aerobic energy
system?
system
?
Rest-to-Exercise: Aerobic
v Assume sitting on the bike requires 15 ATP and 0.3
liters/min of oxygen
v Assume pedaling at a power of 100 watts requires
80 ATP and 1.5 liter/min of oxygen
v A person can go from sitting to full pedaling at 100
watts in a mater of seconds.
v But, it takes 3-4 minutes for the oxygen
requirement to go from 0.3 to 1.5 liters/min
v Where does the ATP needed to pedal at 100 watts
come from until adequate oxygen can be supplied?
Rest-to-Exercise:
The Oxygen Deficit
Aerobic