Download Sports Physiology

Sports Physiology
Prof. dr. Zoran Valić
Department of Physiology
University of Split School of Medicine



heavy exercise is extreme stresses for body
high fever  100%  in metabolism
marathon race  2000%  in metabolism
Female and Male Athletes:
 muscle
strength, pulmonary ventilation and
CO  2/3-3/4 of values recorded in men
 strength per cm2 equal (30-40 N/cm2)
 marathon race  11% slower
 two-way swim across English Channel
 Testosterone (40% more muscle mass)
 27% & 15% percent body fat, respectively
 aggressiveness
Strength, Power, and Endurance
of Muscles
1)
2)
3)
4)
What the muscles can do for you?
What strength they can give?
What power they can achieve?
How long they can continue their activity?
Muscle force (strength):
 determined
mainly by muscle size (training)
 maximal contractile force – 30-40 N/cm2
  quadriceps is 150 cm2 (F=4500-6000N)
 rupture & avulsion of tendons, displaced
cartilages, compression fractures and torn
ligaments
Holding strength (force) of
muscles:
 force
that attempts to stretch out already
contracted muscle
 greater about 40% than contractile strength
 Fquadriceps = 6300-8400N
 internal tearing in the muscle
Power of Muscular Contraction:
 mechanical
work (W) performed by muscle is
amount of force applied by the muscle
multiplied by the distance over which the
force is applied
 power (P) is total amount of work that muscle
performs in a unit period of time (t)
 determined
not only by the strength but also:
distance of contraction and the number of
times that it contracts each minute
 power is generally measured in watts (W, or
in kilogram meters (kg-m) per minute)
Maximal power of all muscles:
Duration of contraction P (W, kg-m/min)
first 8 to 10 seconds
next 1 minute
next 30 minutes
1200/7000
650/4000
300/1700
Athletic (muscle) efficiency:
 efficiency
 velocity of 100-meter dash is only 1.75 times
as great as velocity of a 30-minute race
 depends on muscle supply by nutrients
(glycogen)
 power
Endurance (measured by time):
Nutrition
high-carbohydrate diet
mixed diet
high-fat diet
Time (min)
240
120
85
Amounts of glycogen stored in
the muscle:
Nutrition
high-carbohydrate diet
high-carbohydrate diet
mixed diet
high-fat diet
Amount of glycogen
(g/kg muscle)
40
20
6
Muscle Metabolic Systems in
Exercise:
1)
2)
3)
phosphocreatine-creatine system
glycogen-lactic acid system
aerobic system
Phosphagen system:
(adenosine – PO3  PO3  PO3 -)
  high-energy P bonds (7.3 Cal/mol ATP)
 amount of ATP sufficient for only about 3 s
 phosphocreatine (creatine phosphate, creatine
 PO3 )
 10.3 Cal/mol creatine, quick transfer
 2-4 x more phosphocreatine than ATP
 combined 8-10 s of maximal muscle power
 ATP
Glycogen-Lactic Acid System:
 glucose (glycolysis, anaerobic
metabolism)
 two pyruvic acid molecules – 4 ATP
 without oxygen – lactic acid
 2.5 x more rapid than oxidative mechanism
 provides additional 1.3 to 1.6 minutes of
maximal muscle activity (200-800 m)
 glycogen
Aerobic System:
 glucose,
fatty acids, and amino acids
ATP generation per minute:
Mechanism of Energy Supply M ATP/min
phosphagen system
glycogen-lactic acid system
aerobic system
4
2.5
1
System endurance:
Mechanism of Energy Supply
phosphagen system
glycogen-lactic acid system
aerobic system
Time
8-10 s
1.3-1.6 min
unlimited
Reconstitution of the lactic acid
system:

removal of the excess lactic acid (extreme
fatigue):
1)
2)
small portion is converted back into pyruvic
acid
remaining lactic acid is reconverted into
glucose (in the liver)
Recovery of the Aerobic System
After Exercise:
1)
2)
Oxygen Debt
Recovery of Muscle Glycogen
Oxygen debt:

body contains about 2 L of stored oxygen:
1)
2)
3)
4)



0.5 L in the air of the lungs
0.25 L dissolved in the body fluids
1L combined with the hemoglobin
0.3 L stored in muscle fibers (myoglobin)
all this stored oxygen is used within minute
9 L more reconstituting both phosphagen
system and lactic acid system
total  11.5 L O2 – oxygen debt
Recovery of Muscle Glycogen:

complex matter, often requires days


it is important for an athlete to have a highcarbohydrate diet before a grueling athletic
event
not to participate in exhaustive exercise
during the 48 hours preceding the event
Effect of Athletic Training:
 muscle
strength is not increased without load
 6 nearly maximal contractions performed in
three sets 3 days a week – approximately
optimal increase in muscle strength, without
producing chronic muscle fatigue
 30%  in strength during 6-8 weeks
 simultaneously equal increase in muscle mass
– muscle hypertrophy
Muscle Hypertrophy:


heredity & testosterone secretion
30-60 % increase with training
1)
2)
increased diameter of the muscle fibers
increased numbers of fibers?
Changes that Occur Inside the
Hypertrophied Muscle Fibers:
1)
2)
3)
4)
5)
 numbers of myofibrils
 mitochondrial enzymes for 120%
 ATP and phosphocreatine for 60-80%
 stored glycogen for 50%
 stored triglyceride (fat) for 75-100%
Muscle Fibers Types:
1)
2)
fast-twitch muscle fibers – (gastrocnemius)
– type II (white, a & b)
slow-twitch muscle fibers – (soleus) – type
I (red)
Basic differences between:
1)
2)
3)
4)

diameter of fast-twitch fibers  2x larger
enzymes for anaerobic metabolism  2-3x
more active in fast-twitch fibers (power)
slow-twitch fibers are organized for
endurance, generation of aerobic energy
(more mitochondria and myoglobin)
slow-twitch fibers – more capillaries
genetic inheritance
% of fiber types in quadriceps:
Activity
Fast-twich
Slow-twich
Marathoners
Swimmers
Average male
Weight lifters
Sprinters
Jumpers
18
26
55
55
63
63
82
74
45
45
37
37
Respiration in Exercise:
 depends
activity
on sport discipline, duration of
Oxygen Consumption Under
Maximal Conditions:
Type of subject
VO2MAX (mL/min)
Untrained average male
Trained average male
Male marathon runner
•oxygen consumption for
young man at rest is about 250 ml/min
3600
4000
5100
Pulmonary Ventilation (PV):
Condition
Pulmonary ventilation at maximal
exercise
Maximal breathing capacity
PV (L/min)
100-110
150-170
Limits of Pulmonary Ventilation:



MBC  50% higher than PV during
maximal exercise
respiratory system is not normally the most
limiting factor in delivery of oxygen
element of safety if:
1)
2)
3)
exercise at high altitudes
exercise under very hot conditions
abnormalities in respiratory system
Effect of Training on Vo2 Max:
Max – rate of oxygen usage under
maximal aerobic metabolism
 Vo2 Max of a marathoner is about 45 percent
greater than that of an untrained person
(genetically determined, many years of
training)
 Vo2
Oxygen-Diffusing Capacity of
Athletes:
Condition
Nonathlete at rest
Nonathlete during ME
Speed skaters during ME
Swimmers during ME
Oarsman during ME
ME – maximal exercise
DC (ml/min)
23
48
64
71
80





3x increase in DC (activation of the
pulmonary capillaries)
training procedures increases DC
partial pressures (O2 & CO2) remain nearly
normal during strenuous athletics
regulation of breathing
negative effects of smoking (acute and
chronic)
Cardiovascular System in
Exercise:
 delivering
required oxygen and other
nutrients to the exercising muscles
 arterial blood pressure regulation
 flow decrease during each muscle contraction
 blood flow to muscles during exercise
increases markedly (up to 25x)
Maksimalno povećanje protoka:
Condition
Blood Flow
(ml/min/100g)
Resting blood flow
3.6
Blood flow during maximal exercise
90
Mechanisms of Blood Flow
Increase:
1)
2)
3)
4)
5)
vasodilation caused by the direct effects of
increased muscle metabolism
moderate increase in arterial blood pressure
(30%)
muscle pump
FMD
other theories
CO During Exercise:
Condition
CO in young man at rest
Maximal CO during exercise in young
untrained man
Maximal CO during exercise in
average male marathoner
CO (L/min)
5.5
23
30
(35-40)
Relation of Cardiovascular
Performance to Vo2 Max:




SV & HR increase to 95% of maximal
CO is 90% of maximal CO
PV is 65% of maximal breathing capacity
CO decreases for 50% between age of 20
and 80, maximal breathing capacity
decreases even more, there is a reduction in
skeletal muscle mass as well
Body Heat in Exercise:


maximal efficiency 20-25%
energy converted in muscle work is
ultimately transferred into heat
1)
2)
friction within muscles and joints
friction due to blood flow
Heatstroke:




with very hot and humid conditions or
excess clothing body temperature can easily
rise to 106°-108°F (41°-42°C)
extreme weakness, exhaustion, headache,
dizziness, nausea, profuse sweating,
confusion, staggering gait, collapse,
unconsciousness  death
temperature-regulating mechanism fails
positive feedback-loop
Body Fluids and Salt in Exercise:
 5-10
pound weight loss has been recorded in
athletes in a period of 1 h during endurance
athletic events in hot and humid conditions
 loss of sweat, significantly  performance
 weight loss 5-10% – muscle cramps, nausea
 acclimatization, salt lost, aldosterone
(increasing reabsorption of from sweat)
+
 supplement of K
Drugs and Athletes:
(three cups of coffee  7% improve)
 androgens or anabolic steroids (risk of
cardiovascular damage)
 amphetamines and cocaine (?, deterioration
of performance, sudden death due to
ventricular fibrillation)
 caffeine
Body Fitness Prolongs Life:
 people
who maintain appropriate body fitness
have the additional benefit of prolonged life
 mortality is 3x less in the most fit people than
in the least fit
Mechanisms:
1)
greatly reduce cardiovascular disease (MI
& stroke)
a)
b)
2)
maintenance of lower blood pressure
reduced blood cholesterol and LDA, and
increase in HDL
fit person has more bodily reserves to call
on when does become sick (pneumonia,
cardiac reserve)