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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) What the muscles can do for you?
2) What strength they can give?
3) What power they can achieve?
4) 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 secondsnext 1 minutenext 30 minutes
1200/7000650/4000300/1700
Athletic (muscle) efficiency:
power 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)
Endurance (measured by time):
Nutrition Time (min)high-carbohydrate dietmixed diethigh-fat diet
240120
85
Amounts of glycogen stored in the muscle:
Nutritionhigh-carbohydrate diet
Amount of glycogen (g/kg muscle)
high-carbohydrate diet mixed diethigh-fat diet
4020
6
Muscle Metabolic Systems in Exercise:
1) phosphocreatine-creatine system
2) glycogen-lactic acid system
3) aerobic system
Phosphagen system:
ATP (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
Glycogen-Lactic Acid System:
glycogen 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)
Aerobic System:
glucose, fatty acids, and amino acids
ATP generation per minute:
Mechanism of Energy Supply M ATP/minphosphagen systemglycogen-lactic acid systemaerobic system
42.5
1
System endurance:
Mechanism of Energy Supply Time phosphagen systemglycogen-lactic acid systemaerobic system
8-10 s1.3-1.6 min
unlimited
Reconstitution of the lactic acid system:
removal of the excess lactic acid (extreme fatigue):
1) small portion is converted back into pyruvic acid
2) remaining lactic acid is reconverted into glucose (in the liver)
Recovery of the Aerobic System After Exercise:
1) Oxygen Debt
2) Recovery of Muscle Glycogen
Oxygen debt:
body contains about 2 L of stored oxygen:1) 0.5 L in the air of the lungs
2) 0.25 L dissolved in the body fluids
3) 1L combined with the hemoglobin
4) 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 high-carbohydrate 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) increased diameter of the muscle fibers
2) increased numbers of fibers?
Changes that Occur Inside the Hypertrophied Muscle Fibers:
1) numbers of myofibrils
2) mitochondrial enzymes for 120%
3) ATP and phosphocreatine for 60-80%
4) stored glycogen for 50%
5) stored triglyceride (fat) for 75-100%
Muscle Fibers Types:
1) fast-twitch muscle fibers – (gastrocnemius) – type II (white, a & b)
2) slow-twitch muscle fibers – (soleus) – type I (red)
Basic differences between:
1) diameter of fast-twitch fibers 2x larger
2) enzymes for anaerobic metabolism 2-3x more active in fast-twitch fibers (power)
3) slow-twitch fibers are organized for endurance, generation of aerobic energy (more mitochondria and myoglobin)
4) slow-twitch fibers – more capillaries genetic inheritance
% of fiber types in quadriceps:
Activity Fast-twich Slow-twichMarathonersSwimmers
Average maleWeight lifters
SprintersJumpers
182655556363
827445453737
Respiration in Exercise:
depends on sport discipline, duration of activity
Oxygen Consumption Under Maximal Conditions:
Type of subject VO2MAX (mL/min)
Untrained average maleTrained average maleMale marathon runner
360040005100
• oxygen consumption for young man at rest is about 250 ml/min
Pulmonary Ventilation (PV):
Condition PV (L/min)Pulmonary ventilation at maximal exerciseMaximal breathing capacity
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) exercise at high altitudes
2) exercise under very hot conditions
3) abnormalities in respiratory system
Effect of Training on Vo2 Max:
Vo2 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)
Oxygen-Diffusing Capacity of Athletes:
Condition DC (ml/min)Nonathlete at restNonathlete during MESpeed skaters during MESwimmers during MEOarsman during ME
2348647180
ME – maximal exercise
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 flowBlood flow during maximal exercise
3.690
Mechanisms of Blood Flow Increase:
1) vasodilation caused by the direct effects of increased muscle metabolism
2) moderate increase in arterial blood pressure (30%)
3) muscle pump
4) FMD
5) other theories
CO During Exercise:
Condition CO (L/min)CO in young man at restMaximal CO during exercise in young untrained manMaximal CO during exercise in average male marathoner
5.523
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 heat1) friction within muscles and joints
2) 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:
caffeine (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)
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) maintenance of lower blood pressure
b) reduced blood cholesterol and LDA, and increase in HDL
2) fit person has more bodily reserves to call on when does become sick (pneumonia, cardiac reserve)