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Exercise Physiology
•Driving force behind all types of work
•Conversion of stored energy to mechanical energy
What Influences Athletic Ability?
• Genetics
• Training
• Training
methodology
• Environment
• Nutrition
• Track/Arena
Surfaces
• Shoes
• Jockey
• Etc.
Hemoglobin
concentration
Biomechanics
Gas exchange
ATHLETIC
ABILITY
Anaerobic
capacity
Heart size
Skeletal muscle
properties
ENERGY
• Sources
– Carbohydrates
– Fats
• Effect on performance
– ↓ energy = ↓ performance
– Must meet energy requirement
– Monitor body condition
• ↓ body condition = negative energy balance
Energy Metabolism
• Aerobic
– With oxygen
– Carbohydrate & fat
– CO2, H2O & ATP
• Anaerobic
– Without oxygen
– Carbohydrate
(glycolysis)
– Lactate & ATP
Synthesis of ATP from aerobic and anaerobic metabolism.
Muscle
Glycogen
Blood Glucose
Creatine
Phosphate
Anaerobic
Glycolysis
Lactate
ATP
Myokinase
and CPK
Reactions
Lipolysis
Free-Fatty
Acids
Pyruvate
Oxidative
Metabolism
Oxygen
CO2and
Water
Muscular System
Types of Muscle Fiber
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•
•
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•
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Type I
– Slow contracting
– ↓ glycolytic activity
– Fatigue resistant
– Aerobic metabolism
– Long term/low stress
work
– Endurance
•
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•
•
•
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•
•
Type II
– Fast contracting
– Fatigue quickly
– ↑ Glycolytic activity
– Quick energy bursts
– Speed for longer
distances
– Primarily anaerobic
Breed Differences
Type I fibers
Type II fibers
Energy For Muscle Contraction
• Walking
– Slow contractions
– Primarily type I
fibers
– Fat primary energy
source (very
efficient)
Energy For Muscle Contraction
• Trot and Canter
– Increased contractions
• Increased contractions
require more ATP
• Type II fibers
• Fat cannot be
metabolized
anaerobically
Anaerobic Glycolysis
• Fastest way to
produce ATP
• Less efficient than
aerobic glycolysis
–
–
–
–
Less ATP
Lactic acid produced
Decrease muscle pH
Fatigue/tying up
Horses that can generate a higher
proportion of energy aerobically will
outperform horses with lower
aerobic capacity
Estimated Types Of
Energy Used
Event
Preformed
Energy
Anaerobic
Aerobic
Racing QH
80%
18%
2%
Racing 1000 m
25%
70%
5%
Racing 1600 m
10%
80%
10%
Racing 2400 m
5%
70%
25%
Racing 3200 m
5%
55%
40%
Polo
5%
50%
45%
Estimated Types Of
Energy Used
Event
Preformed
Energy
Anaerobic
Aerobic
Barrel Racing
99%
4%
1%
Cutting
88%
10%
2%
Show Jumping
15%
65%
20%
3 Day (Cross
Country)
10%
40%
50%
Endurance Rides
1%
5%
94%
Pleasure/Equitati
on
1%
2%
97%
Cardiovascular System
• Delivers blood to
body
– O2 from lungs
– Nutrients from
GI tract
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 > 250 li/min
– Equivalent to 55 gal drum
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
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
LocomotorRespiratory
Coupling (LRC)
• Galloping Horse
– 150 Breaths
– 12-15 liters of air
• Trotting Horse
– 70-85 Breaths
– 20-25 liters of air
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)
Thermoregulation
• Thoroughbred (race)
– 2.5 gal
• Endurance horse (50100 miles)
– 6-12 gal
• Three day event
(dressage/cross
country)
– 5-6 gal
• Importance
– Evaporative Cooling
(Sweating)
– Most important route
of heat dissipation
– Requires ample
blood flow to carry
heat from core to
surface
Thermoregulation
• ↑ Exercise intensity > ↑ heat load > ↑ need for
heat dissipation
• Prevent dehydration to prevent thermal injury
– Provision of adequate water
– Normal diet
– Salt & mineral supplement
Thermoregulation
• Dehydration
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Electrolyte & pH disturbances
Fatigue
Gait incoordination (ataxia)
↑ risk of orthopedic injury
Muscle damage
Death
• Supplement electrolytes
– Beginning training program
– Adjusting to high temperature
Types of Training
• Endurance
– Enhances aerobic
system
• High intensity/Quick
burst
– Increases muscle mass
– Strength training
Influence of Training
•
•
•
•
↑ heart size
↓ HR at given speed
Quicker recovery to given heart rate
↑ Capillaries
– ↑ O2 delivered to muscles
• Increase aerobic capacity
Influence of Training
• ↑ Muscle Cell Mitochondria
– ↑ O2 utilization per unit of muscle
• Muscle has quickest adaptation
to training of all body tissues
Conditioning Times of Body Structures
Fit
25
20
15
10
5
Unfit
0
Muscles
Ligaments
Bones
Signs of Fatigue
• Respiration rate > heart rate
–
–
–
–
Inversion
Hyperventilating
Shallow breathing
Shock
• Muscle soreness (lactic acid buildup)
• Ataxia
• Deydration
Conditioning is A Process That
Occurs Over Time