Exercise Physiology

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Exercise Physiology

• Driving force behind all types of work
• Conversion of stored energy to mechanical energy

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What Influences Athletic Ability?

• Genetics
• Training
• Training methodology

• Environment
• Nutrition
• Track/Arena Surfaces
• Shoes
• Jockey
• Etc.

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Hemoglobin concentration
Gas exchange
Biomechanics
ATHLETIC ABILITY
Anaerobic capacity
Heart size
Skeletal muscle properties
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ENERGY

• Sources
• Carbohydrates
• Fats
• Effect on performance
• ? energy ? performance
• Must meet energy requirement
• Monitor body condition
• ? body condition negative energy balance

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Energy Metabolism

• Aerobic
• With oxygen
• Carbohydrate fat
• CO2, H2O ATP

• Anaerobic
• Without oxygen
• Carbohydrate (glycolysis)
• Lactate ATP

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Synthesis of ATP from aerobic and anaerobic
metabolism.
Muscle Glycogen Blood Glucose
Anaerobic Glycolysis
Pyruvate
Lactate
ATP
Creatine Phosphate
Myokinase and CPK Reactions
Lipolysis
CO2and Water
Oxidative Metabolism
Free-Fatty Acids
Oxygen
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Muscular System
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Types of Muscle Fiber

• Type I
• Slow contracting
• ? glycolytic activity
• Fatigue resistant
• Aerobic metabolism
• Long term/low stress
• work
• Endurance

• Type II
• Fast contracting
• Fatigue quickly
• ? Glycolytic activity
• Quick energy bursts
• Speed for longer
• distances
• Primarily anaerobic

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Breed Differences
Type I fibers
Type II fibers
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Energy For Muscle Contraction

• Walking
• Slow contractions
• Primarily type I fibers
• Fat primary energy source (very efficient)

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Energy For Muscle Contraction

• Trot and Canter
• Increased contractions
• Increased contractions require more ATP
• Type II fibers
• Fat cannot be metabolized anaerobically

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Anaerobic Glycolysis

• Fastest way to produce ATP
• Less efficient than aerobic glycolysis
• Less ATP
• Lactic acid produced
• Decrease muscle pH
• Fatigue/tying up

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Horses that can generate a higher proportion of
energy aerobically will outperform horses with
lower aerobic capacity
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Estimated Types Of Energy Used
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Estimated Types Of Energy Used
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Cardiovascular System

• Delivers blood to body
• O2 from lungs
• Nutrients from GI tract

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Cardiovascular System

• Heart rate (HR)
• Resting 30-45
• Exercising 240 bpm max
• Stroke Volume (SV)
• Volume of blood pumped per beat
• 800 900 mls
• HR X SV Cardiac Output
• Can pump gt 250 li/min
• Equivalent to 55 gal drum

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Affect of Exercise On The Cardiovascular System

• ? metabolic activity in limbs ? blood flow
• Three ways to increase blood flow
• Increase cardiac output
• HR and CO proportional to running speed
• Cannot ? HR beyond max
• Increase O2 carried in blood
• Splenic dumping can double O2 carrying capacity
• Redistribute blood flow
• ? to locomotive muscle
• ? to kidneys and small intestines

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Respiratory System

• Respiratory Rate
• Resting - 8-20 breaths per min
• Exercise
• ? O2 consumption
• ? CO2 emission
• To increase air exchange
• ? Respiratory rate
• RR linked to stride freq.
• ? Tidal Volume (TV)
• Air inhaled or exhaled in a breath

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Locomotor-Respiratory Coupling (LRC)

• Galloping Horse
• 150 Breaths
• 12-15 liters of air
• Trotting Horse
• 70-85 Breaths
• 20-25 liters of air

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Respiratory Problems

• Laryngeal hemiplegia
• Partial paralysis of larynx
• Inadequate gas exchange
• Surgical treatment
• Chronic Obstructive Pulmonary Disease
• Decreases respiratory rate
• Hyperallerginc response to dust, mold, irritants
• House outdoors
• Exercise Induced Pulmonary Hemorrhage
• Bleeding in lungs
• Speeds above 14 m/s
• Variable effects
• Furosemide (Lasix)

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Thermoregulation

• Importance
• Evaporative Cooling (Sweating)
• Most important route of heat dissipation
• Requires ample blood flow to carry heat from core
  to surface

• Thoroughbred (race)
• 2.5 gal
• Endurance horse (50-100 miles)
• 6-12 gal
• Three day event (dressage/cross country)
• 5-6 gal

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Thermoregulation

• ? Exercise intensity gt ? heat load gt ? need for
  heat dissipation
• Prevent dehydration to prevent thermal injury
• Provision of adequate water
• Normal diet
• Salt mineral supplement

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Thermoregulation

• Dehydration
• Electrolyte pH disturbances
• Fatigue
• Gait incoordination (ataxia)
• ? risk of orthopedic injury
• Muscle damage
• Death
• Supplement electrolytes
• Beginning training program
• Adjusting to high temperature

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Types of Training

• Endurance
• Enhances aerobic system
• High intensity/Quick burst
• Increases muscle mass
• Strength training

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Influence of Training

• ? heart size
• ? HR at given speed
• Quicker recovery to given heart rate
• ? Capillaries
• ? O2 delivered to muscles
• Increase aerobic capacity

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Influence of Training

• ? Muscle Cell Mitochondria
• ? O2 utilization per unit of muscle
• Muscle has quickest adaptation to training of all
  body tissues

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Conditioning Times of Body Structures
Fit
Months
Unfit
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Signs of Fatigue

• Respiration rate gt heart rate
• Inversion
• Hyperventilating
• Shallow breathing
• Shock
• Muscle soreness (lactic acid buildup)
• Ataxia
• Deydration

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Conditioning is A Process That Occurs Over Time