Sports Physiology

Prof. dr. Zoran ValićDepartment of PhysiologyUniversity 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

24012085

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 system2) glycogen-lactic acid system3) 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 lungs2) 0.25 L dissolved in the body fluids3) 1L combined with the hemoglobin4) 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 altitudes2) exercise under very hot conditions3) 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 pump4) FMD5) 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 joints2) 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 pressureb) reduced blood cholesterol and LDA, and

increase in HDL2) fit person has more bodily reserves to call

on when does become sick (pneumonia, cardiac reserve)