Sports Physiology Prof. dr. Zoran Valić Department of Physiology

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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
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 – N/cm2  quadriceps is 150 cm2 (F= N) 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 = N 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:
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 diet mixed diet high-fat diet 240 120 85

Amounts of glycogen stored in the muscle:
Nutrition high-carbohydrate diet Amount of glycogen (g/kg muscle) high-carbohydrate diet mixed diet high-fat diet 40 20 6

Muscle Metabolic Systems in Exercise:
phosphocreatine-creatine system glycogen-lactic acid system 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 ( m)

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 Time phosphagen system
glycogen-lactic acid system aerobic system 8-10 s min unlimited

Reconstitution of the lactic acid system:
removal of the excess lactic acid (extreme fatigue): 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:
Oxygen Debt Recovery of Muscle Glycogen

Oxygen debt: body contains about 2 L of stored oxygen:
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 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 increased diameter of the muscle fibers increased numbers of fibers?

Changes that Occur Inside the Hypertrophied Muscle Fibers:
 numbers of myofibrils  mitochondrial enzymes for 120%  ATP and phosphocreatine for 60-80%  stored glycogen for 50%  stored triglyceride (fat) for %

Muscle Fibers Types: fast-twitch muscle fibers – (gastrocnemius) – type II (white, a & b) slow-twitch muscle fibers – (soleus) – type I (red)

Basic differences between:
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 63 82 74 45 37

Respiration in Exercise:
depends on sport discipline, duration of activity

Oxygen Consumption Under Maximal Conditions:
Type of subject VO2MAX (mL/min) Untrained average male Trained average male Male marathon runner 3600 4000 5100 oxygen consumption for young man at rest is about 250 ml/min

Pulmonary Ventilation (PV):
Condition PV (L/min) Pulmonary ventilation at maximal exercise Maximal breathing capacity

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: exercise at high altitudes exercise under very hot conditions 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 rest Nonathlete during ME Speed skaters during ME Swimmers during ME Oarsman during ME 23 48 64 71 80 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 flow Blood flow during maximal exercise 3.6 90

Mechanisms of Blood Flow Increase:
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 (L/min) CO in young man at rest
Maximal CO during exercise in young untrained man Maximal CO during exercise in average male marathoner 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 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: 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: greatly reduce cardiovascular disease (MI & stroke)
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)