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Exercise physiology
Exercise physiology
Recommended literature:
1) Wilmore, J. H., & Costill, D. L. (1994). Physiology of sport and exercise.
Champaign, IL: Human Kinetics.
2) Åstrand, P.-O., Rodahl, K., Dahl. H. A., & Strømme, S. B. (2003).
Textbook of Work Physiology: Physiological Bases of Exercise (4th ed.).
Champaign, IL: Human Kinetics.
3) Brooks, G. A., Fahey, T. D., & White, T. P. (1995). Exercise physiology:
human bioenergetics and its applications (2nd ed.).
4) Mountain View, CA: Mayfield Publishing Company. Sharkey, B. J. (1990).
Physiology of fitness. Champaign, IL: Human Kinetics.
Exercise
=> causes the changes in human body
A) Acute response to one bout of exercise
– e.g. ↑ heart rate (HR), ↑ body temperature (HR)
B) Chronic adaptation to repeated bouts of exercise
- e.g. ↓ HR at rest and ↓ HR at exercise (same intensity)
Muscle activity requires energy. During exercise are energy
demands enhanced.
- decrease of ATP, increase of ADP
Muscle contractile work = transforming chemical energy
into kinetic (mechanical) energy
Energy metabolism
A) Anabolism
- creation of reserve (carbohydrate, fat, proteins)
B) Catabolism
– release of energy (glycolysis, lipolysis)
ATP
hydrolisis
phosphorylation
ADP + P + E
ATP – adenosine thriphosphate
- common energy “currency”
ADP – adenosine diphosphate
P - phosphate
E - energy (e.g. for muscle contraction)
Energy metabolism
Energy sources
1] Polysaccharides
2] Fats (triglycerides)
3] Proteins
simple sugars
glucose (glycogen)
fatty acids (FFT) and glycerol
amino acids
Energy metabolism
Glucose is the only one that can be broken down
anaerobically and aerobically as well.
Anaerobic glycolysis
blood
plasma membrane
G
G
cell plasma
G–6-P
Glycogen (GG)
2 ATP (G)
3 ATP (GG)
pyruvic acid
lactic acid
Energy metabolism
Aerobic glycolysis
pyruvic acid (pyruvate)
cell plasma
mitochondrial membrane
mitochondrion
Acetyl CoA
NADH (nicotinamide adenine dinucleotid) and FADH
Citric
acid
cycle
CO2
Energy metabolism
oxidative phosphorylation – in mytochondrion (electron
transport chain)
NADH + O2 + 3ADP
3ATP + NAD + H2O
1 NADH=3 ATP
FADH + O2 + 2ADP
2ATP + FAD + H2O
1 FADH=2 ATP
Energy metabolism
From one molecule
G
GG
Anaerobic glycolysis
2 ATP
3 ATP
Aerobic glycolysis
36 ATP
36 ATP
Total glycolysis
38 ATP
39 ATP
Glycogen reserves are in muscle cells (500 g) and in liver (100 g).
- From 1.500 to 2.500 kcal.
1 calorie (cal) is the amount of energy increases the temperature of 1 gram
H2O from 14.5ºC to 15.5ºC.
Energy metabolism
Fat - triglyceride = FFA (free fat acids) + glycerol in subcutaneous tissue
(141 000 kcal).
Adipose tissue
Glucose metabolism
triglyceride Hormone- FFA + Glycerol
sensitive lipase
NADH
Beta oxidation
Acetyl CoA
NADH
Citric
acid
cycle
CO2
Energy metabolism
anaerobic
aerobic
Glucose
proteins
FFA
and/or
Acetyl CoA
lactic acid
Citric
acid
cycle
NADH
and
FADH
Electron transport chain
plasma membrane
Energy metabolism
Anaerobic metabolism
- only carbohydrate
- increases when lack of O2
- lower amount of ATP, but very fast and huge in short time
- production of lactic acid
Anaerobic metabolism
- carbohydrate, fats, proteins
- enough of O2
- higher amount of ATP, but slower
Note: proteins are not very important sources of energy (5-10%). Amino
acids are preferabely used as a building matters for muscles hormones,
etc.
Energy metabolism
ATP
hydrolisis
phosphorylation
ADP + P + E
ATP is only the one immediate source of energy for
muscles work, etc.
Other ways of the creation (phosporylation):
ATP + P
ATP + AMP
ADP + CP(creatine phosphate)
ADP + ADP
Zones of energy supply
Exercise
Duration Dominative source of Production
intensity (type)
maximum
submaximal
energy
of lactic
till 15 s freeATP,
Small
Anaerobic
of CP
lactic acid
15 – 50 s
ATP, CP, anaerobic
Maximum
glycolysis
Short term
glycolysis
Middle endurance till 10 min
Long term
endurance
aerobic glycolysis
latter lipolysis
FG
FG
FG
and FGO
medium
More than free
aerobic glycolysis,
small
Aerobic
of lactic acid
10 min
fiber type
and FGO
Anaerobic
with and
lactic
till 120 s Anaerobic
aerobicacid
Submax.
endurance
muscle
FGO, SO
SO
Total energy expenditure
- s trváním pokles
(?Havlíčková et al, 1991)
Dominant way of restoration of ATP is oxidative
phosphorylation
Acute reaction of the body (neurohumoral controlled) for
increase in supply of working muscles by energy sources
and O2
- increase glucose in blood (from liver glycogen)
- activation of FFA (activation of hormone sensitive lipase)
Sources of energy by increasing exercise intensity
energy expenditure kJ/min
RQ carbohydrates = 1
RQ =
CO2
1 g = 4,1 kcal
O2
RQ fats = 0,7
1 g = 9,3 kcal
glycogen
fats
glucose
exercise intensity % VO2max
(Hamar & Lipková, 2001)
Sources of energy by increasing exercise intensity
CO2 - expired
RQ =
CO2
O2
O2 - inspired
RQ – respiration quotient – ratio between CO2 and O2
RQ carbohydrates = 1 = 1 l CO2/1 l O2
RQ fats = 0,7 = 0.7 l CO2/1 l O2
RQ normal (mixed) = 0,82
more O2
Lipids (FFA)
- more energy (1 g = 9,3 kcal)
- need more O2 (EE = 4,55 kcal)
- use while enough of O2 (at rest, low intensity of exercise)
Lipids (FFA)
- more energy (1 g = 9,3 kcal)
- need more O2 (EE = 4,55 kcal)
- use while enough of O2 (at rest, low intensity of exercise)
EE
– energetic equivalent
– shows amount of energy released while
applied 1 liter of O2 on carbohydrate or on
FFA
Lipids (FFA)
- more energy (1 g = 9,3 kcal)
- need more O2 (EE = 4,55 kcal)
- use while enough of O2 (at rest, low intensity of exercise)
Carbohydrates
- less energy (1 g = 4,1 kcal)
- need less O2 (EE = 5,05 kcal)
- use while not enough of O2 (higher intensity, and
anaerobically as well)
- small amount is always use at rest
Sources of energy by increasing exercise intensity
energy expenditure kJ/min
RQ carbohydrates = 1
RQ =
CO2
1 g = 4,1 kcal
O2
RQ lipids = 0,7
1 g = 9,3 kcal
glycogen
fats
glucose
exercise intensity % VO2max
(Hamar & Lipková, 2001)
Mechanism of energy release in dependence on
intensity
VO2max
Anaerobic threshold
NOTE:
Ideal model
Aerobic threshold
REST
aerobic
anaerobic
Wasserman scheme of transport O2 a CO2
Muscle
work
Transport
O2 and CO2
Ventilation
O2
Mitochondrion
muscles
cardiovascular s.
lungs
AIR
CO2
(Wasserman, 1999)
The more O2 is delivered to working muscle, the
higher aerobic production of energy (ATP)
Better endurance performance, smaller
production of lactic acid while the same speed of
run, longer lasting exercise, etc.
Wasserman scheme of transport O2 a CO2
Muscle
work
Transport
O2 and CO2
Ventilation
O2
Mitochondrion
muscles
cardiovascular s.
lungs
AIR
CO2
(Wasserman, 1999)
Fick equation:
VO2 = Q × a-vO2
SV
×
HR
VO2 – oxygen consumption [ml/min]
Q – cardiac output [ml/min]
a-vO2 – arteriovenous oxygen difference
SV – stroke volume [ml]
HR – heart rate [beet/min]
a-vO2 – arteriovenous oxygen difference
DA-V – arteriovenous oxygen difference
- difference in the oxygen content of arterial and mixed venous
blood
- the value tells about the amount of oxygen used by working
muscles
- depends on the muscle ability to absorb and use the O2 from
blood (perfusion, amount of capillary, mitochondrion, number
of working muscles, etc.)
- at rest 50 ml O2 from 1 L of blood
- during exercise 150-170 ml O2 1 L of blood
(100 ml krve is saturated by 20 ml O2)
(1 L of blood is saturated by 200 ml O2)
1 L of blood is saturated by 200 ml O2
To ensure during exercise:
↑BF (breathing frequency, rate)
- from 12-16 breath/min up 60 (70 and more)
↑TV (tidal volume)
- from 0.5 L up 3 L
Minute ventilation (VE)
=
- at rest
6 L/min
=
- during maximal
exercise
180 L/min =
BF × TV
12 × 0.5
60 × 3
.
VO2 = Q × DA-V
rest: SEDENTARY
rest: TRAINED
Q = HR × SV
4,9 L = 70 beet/min × 70 ml
4,9 L = 40 beet/min × 120 ml
In work: increase of HR and SV - ↑ Q
- SV increases till HR 110 – 120 beet/min
(from 180 beet/min decreases)
- HRmax = 220 - age
.
VO2 = Q × DA-V
rest: SEDENTARY
rest: TRAINED
Q = HR × TV
4,9 L = 70 beet/min × 70 ml
4,9 L = 40 beet/min × 120 ml
rest: VO2 = 4,9 L of blood × 50 ml O2
VO2 = 245 ml/min
human (70kg):
245 : 70 = 3,5 ml O2/kg/min (1MET)
.
VO2 = Q × DA-V
Max. exercise:
Max. exercise:
SEDENTARY
TRAINED
Q = SF × SV
20 L = 200 beet/min × 120 ml
35 L = 200 beet/min × 175 ml
.
VO2 = Q × DA-V
Max. exercise:
SEDENTARY:
VO2max= 20 L of blood × 157 ml O2
VO2 max= 3140 ml/min
70 kg human:
3140 : 70 = 45 ml O2/kg/min (13 METs)
.
VO2 = Q × DA-V
Max. exercise:
TRAINED:
VO2max= 35 L of blood × 170 ml O2
VO2 max= 5950 ml/min
70 kg human:
5950 : 70 = 85 ml O2/kg/min (25 METs)
Definition and explanation of VO2max
VO2max
- is maximum volume of oxygen that by the body can
consume during intense (maximum), whole body
exercise.
- expressed:
- in L/min
- in ml/kg/min
- METs
1 MET - resting O2 consumption (3.5 ml/kg/min)
10 METs = 35 ml/kg/min
20 METs = 70 ml/kg/min
Importance of VO2max
Higher intensity of exercise
Higher energy demands (ATP)
Increase in oxygen consumption
Lower VO2max = less energy = worse achievement
Importance of VO2max
During endurance activity is being ATP
resynthesized mainly aerobically from lipids
and carbohydrates.
The more is O2 supplied to working muscles,
the more higher is an amount of aerobically
produced energy.
It means higher speed of running, latest
manifestation of fatigue, etc.
It shows the capacity for aerobic energy transfer.
Average values of VO2max
Average (20/30 years) not trained:
- female 35 ml/kg/min
- male 45 ml/kg/min
Trained: to 85 ml/kg/min (cross-country skiing)
Decreases with age. Lower in female.
Average values of VO2max
Limitation factors of VO2max
Muscle
work
Transport
O2 and CO2
Ventilation
O2
muscles
cardiovascular s.
lungs
AIR
CO2
(Wasserman, 1999)
Limitation factors of VO2max
1) Lungs – no limitation factor
2) Muscles – is limitation factor
3) Cardiovascular system – dominant
limitation factor
Wasserman scheme of transport O2 a CO2
Muscle
work
Transport
O2 and CO2
Ventilation
O2
Mitochondrion
muscles
cardiovascular s.
lungs
AIR
CO2
(Wasserman, 1999)
VO2max = Qmax × DA-Vmax
On increase of VO2max participate:
1) Increase of DA-Vmax – shares on increase about
20%
2) Increase of Qmax – shares aboout 70 - 85%
Influence of the gender, health condition, age
Heredity – the increase of VO2max by training only to max. 25%
Gender – in female lower muscle mass, lover hemoglobin
Age – decrease of active body mass, activity of enzymes…
Sources of energy by increasing exercise intensity
energy expenditure kJ/min
RQ carbohydrates = 1
RQ =
CO2
1 g = 4,1 kcal
O2
RQ lipids = 0,7
1 g = 9,3 kcal
glycogen
fats
glucose
exercise intensity % VO2max
(Hamar & Lipková, 2001)
VO2max
[ml/kg/min]
45
AT
50-60%
VO2max
3,5
exercise intensity (speed, load, etc.)
AT (aerobic threshold)
- exercise intensity, when „exclusive“
aerobic covering ends.
- exercise intensity, from which anaerobic
covering starts and lactate is being
produce
- level of lactate: 2 mmol/L of blood
VO2max
[ml/kg/min]
plateau
45
AnT
70-90 %
VO2max
AT
50-60 %
VO2max
3,5
exercise intensity (speed, load, etc.)
AnT (anaerobic threshold)
- exercise intensity, when anaerobic covering
exceed aerobic.
- exercise intensity, when dynamic balance
between production and breakdown of lactate is
disturbed
- level of lactate: 4 mmol/L of blood and is
increasing (onset of blood lactate accumulation).
- at about approximately 8 mmol/L o blood is
impossible to continue in exercise (trained even
30 mmol/L of blood)
AnT (anaerobic threshold)
- can be estimate from VO2max:
AnT = VO2max/3,5 + 60
AnT = 35/3,5 + 60
AnT = 70 %VO2max
1 MET
60 % of VO2max - AT
VO2max
[ml/kg/min]
45
AnT
70-90 %
VO2max
AT
50-60 %
VO2max
3,5
exercise intensity (speed, load, etc.)
lactate
VO2max
[ml/kg/min]
energy sources
onset of lactate accumulation
–
fiber type
↑ pH
45
AnT
70-90 %
VO2max
AT
50-60 %
VO2max
3,5
4 mmol/L
fat < sugar
I., II. a, II. b
L is oxidized (heart ,not working muscles)
2 mmol/L
fat = sugar
? 1,1 mmol/L
fat > sugar
I., II. a
I.
exercise intensity (speed, load, etc.)
(Hamar & Lipková, 2001)
Exercise intensity during endurance activity
(>30 minutes) can not be above AnT.
1)
Before start of exercise
- increase in O2 consumption (emotions, reflexions)
2)
Initial phase of exercise (till 5 minutes)
- rapid increase of the oxygen consumption
3)
Steady state
- balance between the energy required by working
muscles and the rate of ATP produced by aerobic
metabolism
- O2 is almost constant
- lactate level is constant
- HR is in the range ±4 beats (right steady state)
VO2max
[ml/kg/min]
O2 deficit
AnT
3.5
0
before start
5
initial phase
30
steady state
Time [min]
• Oxygen deficit
- Insufficient supply of working muscles with O2, at
the beginning of exercise (slower ↑ SF and SV,
BF and TV).
- disbalance between O2 demands and supply
leads to use of anaerobic metabolism –
production of LACTATE ( ↑ H+ – metabolic
acidosis – death point).
- when O2 demands ensured – second breath
- after termination of exercise the increased O2
consumption persists = oxygen debt
VO2max
[ml/kg/min]
O2 deficit
O2 debt
AnT
3.5
0
before start
5
initial phase
30
steady state
Time [min]
Oxygen debt
- synthesis of ATP and CP
- resynthesis of lactate (back to glycogen in the
liver, and oxidation by muscles and myocardium)
- acceleration of release of lactate from
muscles and better blood perfusion of
muscles resynthesising lactate, is possible by
low intensive exercise:
(till 50 % VO2max – below AT)
- recovery of myoglobin, hemoglobin, hormone, etc.
- the major part (till 30 min), mild oxygen debt can
persist 12-24 hours.
VO2max
[ml/kg/min]
false steady state
- above AnT
major O2 debt
AnT
3.5
0
before start
5
initial phase
25
steady state
Time [min]
VO2max
[ml/kg/min]
smaller O2 debt
AnT
AP
3.5
0
before start
30
2
initial phase
steady state
Time [min]
oxygen consumption (L/min)
trained - steady state is reached earlier
sedentary - steady state is reached latter
rest
exercise
time (min)
(Hamar & Lipková, 2001)
Practical importance of VO2max
VO2max = 70ml/kg/min
AnP = VO2max/3,5 + 60
80%
VO2max = 35 ml/kg/min
70%
male A
female
Practical importance of VO2max
VO2max = 70ml/kg/min
VO2max = 70 ml/kg/min
90%
80%
male A
male B
Critical parameter of aerobic abilities
is not VO2max,
but AnT.
However VO2max is conditional
parameter of AnT.